FXUS63 KLSX 270510
AFDLSX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE ST LOUIS MO
1110 PM CST SUN NOV 26 2006
.DISCUSSION...
LTL CHG IN OVRALL FCST TRENDS IN THE SHORT TERM...AS GFS/NAM REMAIN IN
AGREEMENT THAT UNSEASONABLY WARM AMS WL CONT TO BLANKET REGION.
WITH NO CHG IN AMS CLOUDS AND POSSIBLE PCPN WL BE THE DETERMINING
FACTORS IN HOW WARM TO GO...BUT EVEN WITH A GOOD DEAL OF
CLOUDINESS THIS AFTN TEMPS HAVE SOARED 15-20 DEGREES ABV NORMAL.
HV BASICALLY GONE WITH PERSISTENCE WITH MAX TEMPS OF 65-70 THRU
TUE. ITS POSSIBLE THAT TUE CULD BE A BIT COOLER DUE TO THICKER
CLOUD COVER AND A BIT HIER CHC OF RAIN...BUT MODELS HAVE BEEN WAY
TOO ROBUST WITH LO LVL MOISTURE IN THE WRM SECTOR FOR THE LAST 3-4
DAYS SO JUDGING BY RECENT HISTORY WARMER IS THE WAY TO GO.
BASIC PCPN TRENDS HV ALSO CHANGED LTL THRU TUE...WITH A SLO INCR IN
POPS FROM NW TO SE DURG THE PD AS LO LVLS OF AMS BGNS TO MOISTEN
AND SW UPR LVL FLOW BGNS TO ADV WK SHTWV ENERGY INTO AREA. MET/MAV
POPS BASED OFF OF 12Z RUNS ARE SUGGESTING A BIT OF A BOUNCE IN THE
POPS MON NGT AND/OR TUE INTO THE HIGH CHC/LOW LIKELY
CATEGORIES...BUT HV TROUBLE THIS IS JUSTIFIED IN SE AREAS WHERE
DYNAMICS WL RMN WEAK.
IT APRS THAT THE UNSEASONABLY WARM WEATHER OF THE PAST WEEK WILL
COME TO A RATHER SHOCKING END DURING THE LAST HALF OF THE WEEK.
INITIALLY...IT LOOKED LIKE THE MAIN IMPACT WOULD BE A SHARP DROP
IN TEMPS ON THU...BUT MEDIUM RANGE MODELS HAVE NOW VEERED TOWARD
THE PSBLTY OF WINTERY PRECIPITATION AS WELL.
BFR GOING TOO FAR...IT SHOULD BE SAID THAT MODEL SOLNS IN THE
MEDIUM RANGE ARE QUITE DIVERSE. AND GIVEN WHERE THE SYSTEM IS
CURRENTLY LOCATED DON'T THINK THAT IT'S YET BEEN SAMPLED BY MUCH UA
DATA...SO NWP OUTPUT HAS TO BE TAKEN WITH A GRAIN OF SALT. THAT
SAID...ALL OF THE MEDIUM RANGE MODELS HAVE BEGUN TO EXHIBIT A
SIMILAR TREND. INSTEAD OF DEEPENING TROF OVR ROCKIES THEN SWEEPING
THE SYS EWD...WHICH WULD GIVE US ONE SHOT AT PCPN WITH THE ARRIVAL
OF THE COLDER TEMPS...THE GFS AND ECMWF ARE NOW DRIVING A SECOND
SHOT OF ENERGY INTO THE BASE OF THE TROF...WHICH FIRST CAUSES IT
TO LAG...THEN LIFT OUT AFTER THE COLD AIR HAS PLUNGED INTO THE MID
MS VLY.
OTHER THAN A SLIGHT HICCUP IN LAST NIGHTS SOLNS...MEDIUM RANGE
MODELS HV REMAINED VRY SIMILAR WITH THE INITIAL SWD PUSH OF THE
COLDER AIR INTO AREA. FROPA SHUD OCR OVR N SECTIONS OF FA WED
MRNG...BUT THE FRONT ARRIVING IN THE SOUTHEAST COUNTIES BY ERY
EVE. DURING THIS TIME...ALL OF THE PCPN SHUD BE LQD...WITH A CHC
OF THUNDER CONTG ALG/AHD OF CDFNT.
WED NGT-THU NGT ARE THE MAIN QUESTION MARKS AS FAR AS WINTERY PCPN
IS CONCERNED. GIVEN STRENGTH OF COLD AIR NO DOUBT THAT AMS WL BE
COLD ENUF IN SOME SPOTS OF FA TO CHG LQD PCPN OVR TO SLEET OR
SNOW...MAIN QUESTION IS HOW MUCH PCPN WL OCR AFTER THE AMS
REACHES THE CRITICAL TEMP THRESHOLDS. FOR NOW...AND WITH SO MUCH
UNCERTAINTY IN THE SOLNS THIS FAR OUT...HAVE INTRODUCED RAIN CHGG
TO SNW FROM N TO S ON WED NGT...THEN CONTD MENTION OF PRIMARILY
SNOW OVR SE HLF OF CWA THU AND THU NGT.
THIS CULD BE A MESSY WINTER WX SITUATION FOR SOMEWHERE IN THE MID
MS AND OHIO VALLEYS...DEPENDING UPON HOW THE SYSTEM EVOLVES. HOW
MUCH AND EXACTLY WHERE HEAVIEST PCPN WL OCR DEPENDS UPON HOW INTS
SYS IS AND WHEN IT DECIDES TO LIFT OUT OF THE BASE OF THE
TROF...AND WL HAVE TO WAIT FOR A CPL MORE MODEL RUNS TO TRY TO PIN
THAT DOWN.
TRUETT
&&
.AVIATION...
FOR THE 06Z TAFS...CDFNT EXTDS FM WI SW THRU EXTREME NWRN MO TO
THE OK PNHDL. THIS CDFNT WILL SINK SEWD THRU NWRN MO LT TGT...BUT
SHOULD REMAIN NW OF THE TAF SITES THRU THE PERIOD. THUS A SLY SFC
WND WL CONT AT THE TAF SITES WITH THE LARGE PERSISTANT SFC RDG
ACRS THE SERN US. PLENTY OF MID-HI LVL CLOUDINESS WILL CONT TO
STREAM NEWD THRU THE CWA LT TGT AND MON. MDL RH FCSTS DEPICT
INCRSG LOW LVL MOISTURE...850 MB AND BLW LT TGT MAINLY N AND W OF
THE STL METRO AREA. LWR LVL CLOUDINESS ARND 5000 FT HAS ALREADY
SPREAD INTO UIN ATTM AND WILL CONT TO INCLUDE LWR LVL CLOUD
CEILING IN COU AFTER 09Z AND IN STL AND SUS AFTER 12Z MON...BUT
THIS CEILING HGT WILL STILL BE IN THE VFR CATAGORY. NGM MOS
GUIDANCE CONTS TO BE TOO LOW WITH THE CIG HGT FCST. GFS MOS LOOKS
BETTER BUT STILL MAY BE TOO LOW ON THE CIG HGTS LT TGT AND MON.
ETA MOS GUIDANCE IS THE MOST OPTIMISTIC AND MAY BE THE BEST ON THE
CIG HGT FCST THIS PD. MDLS ARE INDICATING SOME LGT QPF BY MON EVNG
FOR UIN AND COU BUT MAY LEAVE TAFS DRY FOR NOW AS THE BETTER
THREAT FOR SIGNIFICANT RAIN OR SHOWERS SHOULD OCCUR N AND W OF THE
TAF SITES THRU THE PERIOD.
GKS
&&
.LSX WATCHES/WARNINGS/ADVISORIES...
MO...NONE.
IL...NONE.
&&
$$
WFO LSX
FXUS63 KLSX 270856
AFDLSX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE ST LOUIS MO
256 AM CST MON NOV 27 2006
.DISCUSSION...
COLD FRONT EXTENDED FROM CENTRAL IA ACROSS NORTHWEST MO INTO THE OK
PANHANDLE EARLY THIS MORNING WITH A 26 DEGREE DIFFERENCE BETWEEN
SOUTHEAST NEB AND DOWNTOWN KANSAS CITY. WITH SOUTHWESTERLY FLOW
ALOFT CONTINUING THROUGH WEDNESDAY ACROSS THE AREA, EXPECT THE FRONT
TO REMAIN TO THE NORTHWEST OF THE FORECAST AREA UNTIL LATER
WEDNESDAY. THE NAM IS THE FASTEST MODEL WITH THE COLD FRONT BY
WEDNESDAY EVENING WITH THE GFS THE SLOWEST. THE UKMET AND EUROPEAN
ARE IN THE MIDDLE WITH THE FRONTAL POSTION NEAR A RFD-COU-OKC LINE
BY EARLY WEDNESDAY EVENING.
THE ARCTIC AIR THAT HAS BEEN BOTTLED UP IN CANADA SO FAR THIS SEASON
WILL MOVE SOUTH OF THE BORDER THIS WEEK. ARCTIC AIR IS FORECAST TO
SETTLE INTO THE CENTRAL GREAT PLAINS BY EARLY WEDNESDAY. ALL THE
MODELS ARE FORECASTING A TREMENDOUS TEMP GRADIENT AT 850 MBS FROM
NORTHWEST MO INTO THE BLACK HILLS WEDNESDAY MORNING WITH NEARLY A 30
DEGREE C DROP IN TEMP.
LOW LEVEL MOISTURE WILL CONTINUE TO INCREASE ACROSS THE AREA EARLY
IN THE WEEK. THE STRONGEST MOISTURE CONVERGENCE ACROSS THE AREA IS
FORECAST ON WEDNESDAY WHERE THE HIGHEST POPS ARE CURRENTLY FORECAST.
THE LATEST RUN OF THE GFS IS MUCH COLDER ACROSS THE AREA LATER
THURSDAY THAN THE EUROPEAN RUN. IF THE GFS IS ON TRACK, WILL SEE OUR
FIRST SIGNIFICANT SNOW OF THE SEASON ACROSS THE AREA.
NOT MANY CHANGES NEEDED TO BE MADE TO THE PREVIOUS FORECAST AS IT
WAS IN VERY GOOD SHAPE.
SCHROEDER
&&
.AVIATION...
FOR THE 06Z TAFS...CDFNT EXTDS FM WI SW THRU EXTREME NWRN MO TO
THE OK PNHDL. THIS CDFNT WILL SINK SEWD THRU NWRN MO LT TGT...BUT
SHOULD REMAIN NW OF THE TAF SITES THRU THE PERIOD. THUS A SLY SFC
WND WL CONT AT THE TAF SITES WITH THE LARGE PERSISTANT SFC RDG
ACRS THE SERN US. PLENTY OF MID-HI LVL CLOUDINESS WILL CONT TO
STREAM NEWD THRU THE CWA LT TGT AND MON. MDL RH FCSTS DEPICT
INCRSG LOW LVL MOISTURE...850 MB AND BLW LT TGT MAINLY N AND W OF
THE STL METRO AREA. LWR LVL CLOUDINESS ARND 5000 FT HAS ALREADY
SPREAD INTO UIN ATTM AND WILL CONT TO INCLUDE LWR LVL CLOUD
CEILING IN COU AFTER 09Z AND IN STL AND SUS AFTER 12Z MON...BUT
THIS CEILING HGT WILL STILL BE IN THE VFR CATAGORY. NGM MOS
GUIDANCE CONTS TO BE TOO LOW WITH THE CIG HGT FCST. GFS MOS LOOKS
BETTER BUT STILL MAY BE TOO LOW ON THE CIG HGTS LT TGT AND MON.
ETA MOS GUIDANCE IS THE MOST OPTIMISTIC AND MAY BE THE BEST ON THE
CIG HGT FCST THIS PD. MDLS ARE INDICATING SOME LGT QPF BY MON EVNG
FOR UIN AND COU BUT MAY LEAVE TAFS DRY FOR NOW AS THE BETTER
THREAT FOR SIGNIFICANT RAIN OR SHOWERS SHOULD OCCUR N AND W OF THE
TAF SITES THRU THE PERIOD.
GKS
&&
.LSX WATCHES/WARNINGS/ADVISORIES...
MO...NONE.
IL...NONE.
&&
$$
WFO LSX
FXUS63 KLSX 271141
AFDLSX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE ST LOUIS MO
542 AM CST MON NOV 27 2006
.DISCUSSION...
COLD FRONT EXTENDED FROM CENTRAL IA ACROSS NORTHWEST MO INTO THE OK
PANHANDLE EARLY THIS MORNING WITH A 26 DEGREE DIFFERENCE BETWEEN
SOUTHEAST NEB AND DOWNTOWN KANSAS CITY. WITH SOUTHWESTERLY FLOW
ALOFT CONTINUING THROUGH WEDNESDAY ACROSS THE AREA, EXPECT THE FRONT
TO REMAIN TO THE NORTHWEST OF THE FORECAST AREA UNTIL LATER
WEDNESDAY. THE NAM IS THE FASTEST MODEL WITH THE COLD FRONT BY
WEDNESDAY EVENING WITH THE GFS THE SLOWEST. THE UKMET AND EUROPEAN
ARE IN THE MIDDLE WITH THE FRONTAL POSTION NEAR A RFD-COU-OKC LINE
BY EARLY WEDNESDAY EVENING.
THE ARCTIC AIR THAT HAS BEEN BOTTLED UP IN CANADA SO FAR THIS SEASON
WILL MOVE SOUTH OF THE BORDER THIS WEEK. ARCTIC AIR IS FORECAST TO
SETTLE INTO THE CENTRAL GREAT PLAINS BY EARLY WEDNESDAY. ALL THE
MODELS ARE FORECASTING A TREMENDOUS TEMP GRADIENT AT 850 MBS FROM
NORTHWEST MO INTO THE BLACK HILLS WEDNESDAY MORNING WITH NEARLY A 30
DEGREE C DROP IN TEMP.
LOW LEVEL MOISTURE WILL CONTINUE TO INCREASE ACROSS THE AREA EARLY
IN THE WEEK. THE STRONGEST MOISTURE CONVERGENCE ACROSS THE AREA IS
FORECAST ON WEDNESDAY WHERE THE HIGHEST POPS ARE CURRENTLY FORECAST.
THE LATEST RUN OF THE GFS IS MUCH COLDER ACROSS THE AREA LATER
THURSDAY THAN THE EUROPEAN RUN. IF THE GFS IS ON TRACK, WILL SEE OUR
FIRST SIGNIFICANT SNOW OF THE SEASON ACROSS THE AREA.
NOT MANY CHANGES NEEDED TO BE MADE TO THE PREVIOUS FORECAST AS IT
WAS IN VERY GOOD SHAPE.
SCHROEDER
&&
.AVIATION...
FOR THE 12Z TAFS...CDFNT EXTDS FM SRN WI SW THRU ERN IA AND INTO
NWRN MO...THEN FURTHER SWWD TO THE OK PNHDL. THIS CDFNT WILL REMAIN
STALLED OVER THAT AREA TODAY...BEFORE LIFTING BACK NORTH TONIGHT. SO
IN THE MEANTIME...ALL TAF SITES TO REMAIN IN THE WARM SECTOR WITH
SOUTHERLY WINDS PERSISTING THROUGHOUT THE FORECAST PERIOD. TRICKY
PART WILL BE CLOUDS FOR TAF SITES. CIGS TO REMAIN VFR WITH CU
DEVELOPMENT ON THE INCREASE DURING THE DAYTIME HOURS AS LOW LEVEL
MOISTURE IS ON THE INCREASE AS WELL. WILL NOT SEE MUCH IN THE WAY OF
PCPN...BUT KEPT VCNTY RW MENTION FOR KUIN AND KCOU FOR THE EVENING
HOURS...WHILE HAVE PROB30 GROUP FROM 06Z TO 12Z FOR KUIN ONLY...AS
THEY REMAIN CLOSEST TO THE FRONTAL BOUNDARY. KSTL AND KSUS TO REMAIN
DRY.
BYRD
&&
.LSX WATCHES/WARNINGS/ADVISORIES...
MO...NONE.
IL...NONE.
&&
$$
WFO LSX
FXUS63 KLSX 271734
AFDLSX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE ST LOUIS MO
1134 AM CST MON NOV 27 2006
.DISCUSSION...
COLD FRONT EXTENDED FROM CENTRAL IA ACROSS NORTHWEST MO INTO THE OK
PANHANDLE EARLY THIS MORNING WITH A 26 DEGREE DIFFERENCE BETWEEN
SOUTHEAST NEB AND DOWNTOWN KANSAS CITY. WITH SOUTHWESTERLY FLOW
ALOFT CONTINUING THROUGH WEDNESDAY ACROSS THE AREA, EXPECT THE FRONT
TO REMAIN TO THE NORTHWEST OF THE FORECAST AREA UNTIL LATER
WEDNESDAY. THE NAM IS THE FASTEST MODEL WITH THE COLD FRONT BY
WEDNESDAY EVENING WITH THE GFS THE SLOWEST. THE UKMET AND EUROPEAN
ARE IN THE MIDDLE WITH THE FRONTAL POSTION NEAR A RFD-COU-OKC LINE
BY EARLY WEDNESDAY EVENING.
THE ARCTIC AIR THAT HAS BEEN BOTTLED UP IN CANADA SO FAR THIS SEASON
WILL MOVE SOUTH OF THE BORDER THIS WEEK. ARCTIC AIR IS FORECAST TO
SETTLE INTO THE CENTRAL GREAT PLAINS BY EARLY WEDNESDAY. ALL THE
MODELS ARE FORECASTING A TREMENDOUS TEMP GRADIENT AT 850 MBS FROM
NORTHWEST MO INTO THE BLACK HILLS WEDNESDAY MORNING WITH NEARLY A 30
DEGREE C DROP IN TEMP.
LOW LEVEL MOISTURE WILL CONTINUE TO INCREASE ACROSS THE AREA EARLY
IN THE WEEK. THE STRONGEST MOISTURE CONVERGENCE ACROSS THE AREA IS
FORECAST ON WEDNESDAY WHERE THE HIGHEST POPS ARE CURRENTLY FORECAST.
THE LATEST RUN OF THE GFS IS MUCH COLDER ACROSS THE AREA LATER
THURSDAY THAN THE EUROPEAN RUN. IF THE GFS IS ON TRACK, WILL SEE OUR
FIRST SIGNIFICANT SNOW OF THE SEASON ACROSS THE AREA.
NOT MANY CHANGES NEEDED TO BE MADE TO THE PREVIOUS FORECAST AS IT
WAS IN VERY GOOD SHAPE.
SCHROEDER
&&
.AVIATION...
FOR THE 18Z TAFS...
SURFACE FRONT OVER NORTHWEST MISSOURI WILL BE PUSHED BACK
NORTHWARD BY INCREASING SOUTH-SOUTHWESTERLY FLOW. GUIDANCE STILL
SEEMS TO BE OVER-DOING THE LOW LEVEL RELATIVE HUMIDITY
FORECASTS...SO STILL THINK WE'LL HAVE VFR CONDITIONS PREVAILING
ACROSS THE AREA THROUGH 18Z TUESDAY. THE ONE EXCEPTION WILL BE IN
ISOLATED/WIDELY SCATTERED SHOWERS THAT WILL LIKELY MOVE INTO THE
AREA LATER THIS AFTERNOON AND CONTINUING INTO THE NIGHTTIME HOURS.
THINK THE PRIMARY THREAT FOR MARGINAL CONDITIONS WILL BE OVER
CENTRAL AND NORTHEAST MISSOURI...BUT AS MENTIONED BEFORE IT WILL
MOST LIKELY BE ISOLATED OR WIDELY SCATTERED WITH THE SHOWERS.
CARNEY
&&
.LSX WATCHES/WARNINGS/ADVISORIES...
MO...NONE.
IL...NONE.
&&
$$
WFO LSX
FXUS63 KLSX 272215
AFDLSX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE ST LOUIS MO
415 PM CST MON NOV 27 2006
.DISCUSSION...
MODELS ARE CONTG TRENDS THAT BEGAN LATE SAT AND SUN...POINTING TO
AN INCRG THRT OF SVR WINTER WX LATE WED NIGHT...AND WITH THIS THRT CONTG
THU AND INTO THU NGT. IT CERTAINLY LOOKS LIKE AN ABRUPT AND
DRAMATIC END TO THE UNSEASONBLY MILD LATE NOVEMBER WX THAT WE'VE
BEEN EXPERIENCING FOR THE PAST WEEK.
AS WE WAIT FOR THIS SYSTEM TO PUSH INTO OUR AREA MILD AMS WL RMN
DRAPED ACR THE REGION INTO WED..WITH A GRDL INCR IN POPS FROM W TO
E WITH TIME...AND GENL FCST TRENDS THRU TUE NGT RMN
UNCHANGED. HWVR MODELS HAVE SLOWED INITIAL PUSH OF SFC CDFNT INTO
AREA UNTIL WED NGT...SO IT NOW APRS THAT MOST OF THE CWA WL RMN IN
THE WRM AIR DURG THE DAY ON WED AND HV ADJ MAX TEMPS ACCORDINGLY
TO GIVE REGION ONE LAST UNSEASONABLY WRM DAY.
COLD AIR SHUD BGN TO FILTER INTO AREA WED NGT...WITH A SLOW BUT
STEADY DEEPENING OF THIS CHILLY AMS OCRG THU AND INTO THU NGT.
THERMAL PROFILES VARY BTWN THE MODELS...WITH THE NAM ALLOWING A
QUICKER SWD PUSH TO THE LO LVL COLD AIR AS COMPARED TO THE GFS.
MODEL TRENDS HV CERTAINLY BEEN TO SLOW THE SWD PUSH...BUT VRY
CONCERNED THAT ONCE THIS VERY COLD AMS BGNS TO MOVE IT WL BE TOUGH
TO STOP. FCST SOUNDINGS FROM EITHER MODEL SUGGEST A PD OF FRZG
RAIN AND/OR SLEET...WITH A MUCH LONGER PD OF THIS ICY MIX DEPICTED
BY THE FASTER NAM FCSTS. ITS PSBL THAT ZR AND IP MAY CAUSE SGFNT
ICING MAY OCR OVR NW HALF OF THE CWA DURG THE DAY ON THU...BFR
THE COLUMN COOLS ENUF TO CHG THE PCPN TO ALL SNOW DURG THE AFTN
AND ERY EVE. STG FORCING CERTAINLY APRS IN THE OFFING...WHICH WL
GENERATE MORE THAN ENUF QPF TO CAUSE SERIOUS PROBLEMS IF THE SFC
LYR DOES DROP BLO FREEZING.
ICY MIX WL CONT TO DROP S INTO SE MO/SE IL THU EVE WITH THE 32F
ISOTHERM WITH PCPN CHGG TO ALL SNOW OVR THIS AREA BY ARND
MIDNIGHT...WHILE AMS OVR NW HLF OF CWA WL CERTAINLY BE COLD ENUF
FOR ALL SNOW BY THIS TIME. AND THIS IS WHEN THE SECOND WHAMMY OF
THIS STORM CULD OCR. AS BASE OF TROF BGNS TO LIFT OUT...BOTH THE
NAM AND GFS ARE FCSTG A SECOND SWATH OF PCPN...WHICH SHUD BE ALL
SNOW...TO DVLP AND MOVE ACR THE AREA. GFS IS MUCH MORE INTS WITH
THIS FTR AND ACTUALLY CUTS OFF AN UPR LOW...WHILE NAM IS A BIT
LESS ROBUST. EXACT PLACEMENT OF THIS POTENTIAL HVY SNOW BAND WL BE
DETERMINED BY INTENSITY OF THE UPR SYS...IF ITS AS STG AS THE GFS
HVY SNOW CULD OCR WELL INTO THE COLD AIR...IF NAM VERIFIES SNW
BAND CULD SET UP OVR SE MO INTO S IL.
OBVIOUSLY...ITS STILL TOO EARLY TO PIN DOWN THE EXACT TRENDS OF
THIS STORM SYSTEM...SO ITS A BIT PREMATURE TO ISSUE A WATCH.
HWVR...WITH THE POTENTIAL OF SUCH A SERIOUS STORM...AND OCRG AFTER
SUCH A MILD SPELL...WILL ISSUE SPS WITH THE AFTN ZN/GRIDS TO
HIGHLIGHT AND AMPLIFY THE THREAT.
TRUETT
&&
.AVIATION...
FOR THE 18Z TAFS...
SURFACE FRONT OVER NORTHWEST MISSOURI WILL BE PUSHED BACK
NORTHWARD BY INCREASING SOUTH-SOUTHWESTERLY FLOW. GUIDANCE STILL
SEEMS TO BE OVER-DOING THE LOW LEVEL RELATIVE HUMIDITY
FORECASTS...SO STILL THINK WE'LL HAVE VFR CONDITIONS PREVAILING
ACROSS THE AREA THROUGH 18Z TUESDAY. THE ONE EXCEPTION WILL BE IN
ISOLATED/WIDELY SCATTERED SHOWERS THAT WILL LIKELY MOVE INTO THE
AREA LATER THIS AFTERNOON AND CONTINUING INTO THE NIGHTTIME HOURS.
THINK THE PRIMARY THREAT FOR MARGINAL CONDITIONS WILL BE OVER
CENTRAL AND NORTHEAST MISSOURI...BUT AS MENTIONED BEFORE IT WILL
MOST LIKELY BE ISOLATED OR WIDELY SCATTERED WITH THE SHOWERS.
CARNEY
&&
.LSX WATCHES/WARNINGS/ADVISORIES...
MO...NONE.
IL...NONE.
&&
$$
WFO LSX
FXUS63 KLSX 280010
AFDLSX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE ST LOUIS MO
610 PM CST MON NOV 27 2006
.DISCUSSION...
MODELS ARE CONTG TRENDS THAT BEGAN LATE SAT AND SUN...POINTING TO
AN INCRG THRT OF SVR WINTER WX LATE WED NIGHT...AND WITH THIS THRT CONTG
THU AND INTO THU NGT. IT CERTAINLY LOOKS LIKE AN ABRUPT AND
DRAMATIC END TO THE UNSEASONBLY MILD LATE NOVEMBER WX THAT WE'VE
BEEN EXPERIENCING FOR THE PAST WEEK.
AS WE WAIT FOR THIS SYSTEM TO PUSH INTO OUR AREA MILD AMS WL RMN
DRAPED ACR THE REGION INTO WED..WITH A GRDL INCR IN POPS FROM W TO
E WITH TIME...AND GENL FCST TRENDS THRU TUE NGT RMN
UNCHANGED. HWVR MODELS HAVE SLOWED INITIAL PUSH OF SFC CDFNT INTO
AREA UNTIL WED NGT...SO IT NOW APRS THAT MOST OF THE CWA WL RMN IN
THE WRM AIR DURG THE DAY ON WED AND HV ADJ MAX TEMPS ACCORDINGLY
TO GIVE REGION ONE LAST UNSEASONABLY WRM DAY.
COLD AIR SHUD BGN TO FILTER INTO AREA WED NGT...WITH A SLOW BUT
STEADY DEEPENING OF THIS CHILLY AMS OCRG THU AND INTO THU NGT.
THERMAL PROFILES VARY BTWN THE MODELS...WITH THE NAM ALLOWING A
QUICKER SWD PUSH TO THE LO LVL COLD AIR AS COMPARED TO THE GFS.
MODEL TRENDS HV CERTAINLY BEEN TO SLOW THE SWD PUSH...BUT VRY
CONCERNED THAT ONCE THIS VERY COLD AMS BGNS TO MOVE IT WL BE TOUGH
TO STOP. FCST SOUNDINGS FROM EITHER MODEL SUGGEST A PD OF FRZG
RAIN AND/OR SLEET...WITH A MUCH LONGER PD OF THIS ICY MIX DEPICTED
BY THE FASTER NAM FCSTS. ITS PSBL THAT ZR AND IP MAY CAUSE SGFNT
ICING MAY OCR OVR NW HALF OF THE CWA DURG THE DAY ON THU...BFR
THE COLUMN COOLS ENUF TO CHG THE PCPN TO ALL SNOW DURG THE AFTN
AND ERY EVE. STG FORCING CERTAINLY APRS IN THE OFFING...WHICH WL
GENERATE MORE THAN ENUF QPF TO CAUSE SERIOUS PROBLEMS IF THE SFC
LYR DOES DROP BLO FREEZING.
ICY MIX WL CONT TO DROP S INTO SE MO/SE IL THU EVE WITH THE 32F
ISOTHERM WITH PCPN CHGG TO ALL SNOW OVR THIS AREA BY ARND
MIDNIGHT...WHILE AMS OVR NW HLF OF CWA WL CERTAINLY BE COLD ENUF
FOR ALL SNOW BY THIS TIME. AND THIS IS WHEN THE SECOND WHAMMY OF
THIS STORM CULD OCR. AS BASE OF TROF BGNS TO LIFT OUT...BOTH THE
NAM AND GFS ARE FCSTG A SECOND SWATH OF PCPN...WHICH SHUD BE ALL
SNOW...TO DVLP AND MOVE ACR THE AREA. GFS IS MUCH MORE INTS WITH
THIS FTR AND ACTUALLY CUTS OFF AN UPR LOW...WHILE NAM IS A BIT
LESS ROBUST. EXACT PLACEMENT OF THIS POTENTIAL HVY SNOW BAND WL BE
DETERMINED BY INTENSITY OF THE UPR SYS...IF ITS AS STG AS THE GFS
HVY SNOW CULD OCR WELL INTO THE COLD AIR...IF NAM VERIFIES SNW
BAND CULD SET UP OVR SE MO INTO S IL.
OBVIOUSLY...ITS STILL TOO EARLY TO PIN DOWN THE EXACT TRENDS OF
THIS STORM SYSTEM...SO ITS A BIT PREMATURE TO ISSUE A WATCH.
HWVR...WITH THE POTENTIAL OF SUCH A SERIOUS STORM...AND OCRG AFTER
SUCH A MILD SPELL...WILL ISSUE SPS WITH THE AFTN ZN/GRIDS TO
HIGHLIGHT AND AMPLIFY THE THREAT.
TRUETT
&&
.AVIATION...
FOR THE 00Z TAFS...S-SELY SFC WNDS WL CONT OVR THE CWA TGT AND TUE
WITH A STG SFC RDG OVR THE ERN US AND A STG CDFNT PUSHING SEWD
THRU THE NRN PLAINS. SFC WNDS WILL LIKELY INCRS LTR TGT IN UIN AND
COU AS A SWLY LLJ TRANSLATES EWD INTO THE CWA LT TGT. SLY SFC WNDS
WILL BE STGR AND GUSTY ON TUE AS THE SFC PRESSURE GRADIENT
TIGHTENS OVR THE CWA BTWN THE STG ERN US RDG AND APPROACHING STG
CDFNT IN THE NRN PLAINS. RADAR CURRENTLY SHOWING SCT SHRA MOVG
NEWD THRU THE UIN VCNTY AND WILL INCLUDE A TEMPO GRP OF 5SM -SHRA
OVC030 IN THE UIN TAF FOR THE EARLY EVNG HRS. LOOKS LIKE THERE
WILL BE MORE SHRA LT TGT AND TUE MRNG IN UIN AND COU AND POSSIBLY
IN THE STL METRO AREA PER BOTH NAM AND GFS QPF FCST. MDL RH FCSTS
KEEP THE HIGH BNDRY LYR RH N AND W OF THE TAF SITES...ALTHOUGH
THE PREVAILING CEILING HGTS SHOULD LWR TGT INTO TUE AT THE TAF
SITES. WILL KEEP THE PREVAILING CIG HGTS ABV MVFR AND LEAN TWD THE
MORE OPTIMISTIC CEILING HGT FCST OF THE ETA MOS AS THE GFS AND
ESPECIALLY THE NGM MOS CIG HGT FCST CONT TO APR TOO LOW.
GKS
&&
.LSX WATCHES/WARNINGS/ADVISORIES...
MO...NONE.
IL...NONE.
&&
$$
WFO LSX
FXUS63 KLSX 280514
AFDLSX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE ST LOUIS MO
1114 PM CST MON NOV 27 2006
.DISCUSSION...
MODELS ARE CONTG TRENDS THAT BEGAN LATE SAT AND SUN...POINTING TO
AN INCRG THRT OF SVR WINTER WX LATE WED NIGHT...AND WITH THIS THRT CONTG
THU AND INTO THU NGT. IT CERTAINLY LOOKS LIKE AN ABRUPT AND
DRAMATIC END TO THE UNSEASONBLY MILD LATE NOVEMBER WX THAT WE'VE
BEEN EXPERIENCING FOR THE PAST WEEK.
AS WE WAIT FOR THIS SYSTEM TO PUSH INTO OUR AREA MILD AMS WL RMN
DRAPED ACR THE REGION INTO WED..WITH A GRDL INCR IN POPS FROM W TO
E WITH TIME...AND GENL FCST TRENDS THRU TUE NGT RMN
UNCHANGED. HWVR MODELS HAVE SLOWED INITIAL PUSH OF SFC CDFNT INTO
AREA UNTIL WED NGT...SO IT NOW APRS THAT MOST OF THE CWA WL RMN IN
THE WRM AIR DURG THE DAY ON WED AND HV ADJ MAX TEMPS ACCORDINGLY
TO GIVE REGION ONE LAST UNSEASONABLY WRM DAY.
COLD AIR SHUD BGN TO FILTER INTO AREA WED NGT...WITH A SLOW BUT
STEADY DEEPENING OF THIS CHILLY AMS OCRG THU AND INTO THU NGT.
THERMAL PROFILES VARY BTWN THE MODELS...WITH THE NAM ALLOWING A
QUICKER SWD PUSH TO THE LO LVL COLD AIR AS COMPARED TO THE GFS.
MODEL TRENDS HV CERTAINLY BEEN TO SLOW THE SWD PUSH...BUT VRY
CONCERNED THAT ONCE THIS VERY COLD AMS BGNS TO MOVE IT WL BE TOUGH
TO STOP. FCST SOUNDINGS FROM EITHER MODEL SUGGEST A PD OF FRZG
RAIN AND/OR SLEET...WITH A MUCH LONGER PD OF THIS ICY MIX DEPICTED
BY THE FASTER NAM FCSTS. ITS PSBL THAT ZR AND IP MAY CAUSE SGFNT
ICING MAY OCR OVR NW HALF OF THE CWA DURG THE DAY ON THU...BFR
THE COLUMN COOLS ENUF TO CHG THE PCPN TO ALL SNOW DURG THE AFTN
AND ERY EVE. STG FORCING CERTAINLY APRS IN THE OFFING...WHICH WL
GENERATE MORE THAN ENUF QPF TO CAUSE SERIOUS PROBLEMS IF THE SFC
LYR DOES DROP BLO FREEZING.
ICY MIX WL CONT TO DROP S INTO SE MO/SE IL THU EVE WITH THE 32F
ISOTHERM WITH PCPN CHGG TO ALL SNOW OVR THIS AREA BY ARND
MIDNIGHT...WHILE AMS OVR NW HLF OF CWA WL CERTAINLY BE COLD ENUF
FOR ALL SNOW BY THIS TIME. AND THIS IS WHEN THE SECOND WHAMMY OF
THIS STORM CULD OCR. AS BASE OF TROF BGNS TO LIFT OUT...BOTH THE
NAM AND GFS ARE FCSTG A SECOND SWATH OF PCPN...WHICH SHUD BE ALL
SNOW...TO DVLP AND MOVE ACR THE AREA. GFS IS MUCH MORE INTS WITH
THIS FTR AND ACTUALLY CUTS OFF AN UPR LOW...WHILE NAM IS A BIT
LESS ROBUST. EXACT PLACEMENT OF THIS POTENTIAL HVY SNOW BAND WL BE
DETERMINED BY INTENSITY OF THE UPR SYS...IF ITS AS STG AS THE GFS
HVY SNOW CULD OCR WELL INTO THE COLD AIR...IF NAM VERIFIES SNW
BAND CULD SET UP OVR SE MO INTO S IL.
OBVIOUSLY...ITS STILL TOO EARLY TO PIN DOWN THE EXACT TRENDS OF
THIS STORM SYSTEM...SO ITS A BIT PREMATURE TO ISSUE A WATCH.
HWVR...WITH THE POTENTIAL OF SUCH A SERIOUS STORM...AND OCRG AFTER
SUCH A MILD SPELL...WILL ISSUE SPS WITH THE AFTN ZN/GRIDS TO
HIGHLIGHT AND AMPLIFY THE THREAT.
TRUETT
&&
.AVIATION...
FOR THE 06Z TAFS...S-SELY SFC WNDS WL CONT OVR THE CWA LT TGT AND
TUE WITH A STG SFC RDG OVR THE ERN US AND A STG CDFNT PUSHING SEWD
THRU THE NRN PLAINS. SFC WNDS WILL LIKELY INCRS LT TGT IN UIN AND
COU AS A SWLY LLJ TRANSLATES EWD INTO THE CWA LT TGT. SLY SFC WNDS
WILL BE STGR AND GUSTY ON TUE AS THE SFC PRESSURE GRADIENT
TIGHTENS OVR THE CWA BTWN THE STG ERN US RDG AND APPROACHING STG
CDFNT IN THE NRN PLAINS. RADAR CURRENTLY SHOWING SCT LGT SHRA
ACTIVITY BTWN COU AND UIN BUT THE HEAVIER AND MORE WIDESPREAD
SHOWERS WILL LIKELY REMAIN N AND W OF UIN AND COU LT TGT. MAY
MENTION A TEMPO GRP WITH LGT SHRA LT TGT AND EARLY TUE MRNG IN UIN
AND COU AND POSSIBLY IN THE STL METRO AREA TUE MRNG AS BOTH NAM
AND GFS MDLS HAVE QPF FCST LT TGT AND TUE MRNG MAINLY N AND W OF
STL. MDL RH FCSTS KEEP THE HIGH BNDRY LYR RH N AND W OF THE TAF
SITES LT TGT...ALTHOUGH THE PREVAILING CEILING HGTS SHOULD LWR LT
TGT INTO TUE AT THE TAF SITES. WILL KEEP THE PREVAILING CIG HGTS
ABV MVFR AND LEAN TWD THE MORE OPTIMISTIC CEILING HGT FCST OF THE
ETA MOS AS THE GFS AND ESPECIALLY THE NGM MOS CIG HGT FCST CONT TO
APR TOO LOW. MDL TIME HGT SECTIONS OF RH SHOW PLENTY OF RH ARND
700 MB LT TGT AND TUE MRNG...THEN INCRSG BNDRY LYR RH TUE EVNG.
GKS
&&
.LSX WATCHES/WARNINGS/ADVISORIES...
MO...NONE.
IL...NONE.
&&
$$
WFO LSX
FXUS63 KLSX 280902
AFDLSX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE ST LOUIS MO
302 AM CST TUE NOV 28 2006
.DISCUSSION...
...MAJOR WINTER STORM TO AFFECT REGION THURSDAY AND THURSDAY NIGHT...
THE UNSEASONABLY WARM WEATHER OF LATE WILL BE REPLACED WITH MORE
WINTER LIKE TEMPERATURES AS A POWERFUL COLD FRONT IS POISED TO
MOVE ACROSS THE REGION WEDNESDAY NIGHT AND THURSDAY. INITIALLY THE
COLD AIR WILL BE SHALLOW BEHIND THE FRONT...LEADING TO
PRECIPITATION TYPE ISSUES AS MODEL GUIDANCE DEPICTS QUITE A BIT OF
POSTFRONTAL QPF. INITIALLY A FREEZING RAIN AND SLEET MIXTURE WILL
OCCUR...BUT AS THE ARCTIC AIR MASS BUILDS ACROSS THE REGION
THURSDAY AFTERNOON AND EVENING...THE WINTRY MIX WILL TURN TO SNOW
FROM WEST TO EAST AS A DEFORMATION ZONE SETS UP ACROSS THE REGION.
SIGNIFICANT ICE AND SNOW ACCUMULATIONS WILL OCCUR WITH THIS STORM
SYSTEM...THE ONLY REAL QUESTION IS EXACTLY WHERE?
CWA TO REMAIN IN WARM SECTOR AND SOUTHWEST FLOW ALOFT THROUGH
WEDNESDAY WITH ABOVE NORMAL TEMPERATURE REGIME CONTINUING. GIVEN
WARM CONVEYOR BELT IS ALREADY WELL ESTABILISHED WITH GULF WIDE
OPEN...ANY SHORTWAVE RIPPLING ALONG WILL CAUSE SHOWERS AND
THUNDERSTORMS TO DEVELOP. SIMILAR TO WHAT IS OCCURRING EARLY THIS
MORNING.
SURE THERE ARE DIFFERENCES IN THE EXACT TIMING OF THE FRONT AND
DEPTH OF COLD AIR BETWEEN THE GFS AND NAM...BUT I WOULD EXPECT THAT
IN A 48HR MODEL FORECAST. THE BOTTOM LINE IS...BOTH MODELS REVEAL
THE POTENTIAL FOR A SIGNIFICANT ICING EVENT ON THURSDAY FOLLOWED
BY A CLASSIC HEAVY SNOW SCENARIO FOR THURSDAY NIGHT AS A WAVE OF
LOW PRESSURE DEVELOPS ALONG THE FRONTAL BOUNDARY AND MOVES SOUTH
AND THEN EAST OF THE CWA.
THE DETAILS OF THIS FORECAST CLOSELY FOLLOW THE NAM...GIVEN ITS
ABILITY TO CAPTURE AND FORECAST THE THERMODYNAMIC STRUCTURE OF THE
THOSE LOWEST AND MOST CRITICAL LAYERS OF THE ATMOSPHERE.
PLAN ON UPDATING THE SPECIAL WEATHER STATEMENT...AND INCLUDE STRONG
WORDING IN THE HWO THIS MORNING. BEING AS SYSTEM WILL NOT AFFECT THE
CWA UNTIL 5TH AND 6TH PERIOD...FEEL IT IS A LITTLE PREMATURE TO
ISSUE A WINTER STORM WATCH
CVKING
&&
.AVIATION...
FOR THE 06Z TAFS...S-SELY SFC WNDS WL CONT OVR THE CWA LT TGT AND
TUE WITH A STG SFC RDG OVR THE ERN US AND A STG CDFNT PUSHING SEWD
THRU THE NRN PLAINS. SFC WNDS WILL LIKELY INCRS LT TGT IN UIN AND
COU AS A SWLY LLJ TRANSLATES EWD INTO THE CWA LT TGT. SLY SFC WNDS
WILL BE STGR AND GUSTY ON TUE AS THE SFC PRESSURE GRADIENT
TIGHTENS OVR THE CWA BTWN THE STG ERN US RDG AND APPROACHING STG
CDFNT IN THE NRN PLAINS. RADAR CURRENTLY SHOWING SCT LGT SHRA
ACTIVITY BTWN COU AND UIN BUT THE HEAVIER AND MORE WIDESPREAD
SHOWERS WILL LIKELY REMAIN N AND W OF UIN AND COU LT TGT. MAY
MENTION A TEMPO GRP WITH LGT SHRA LT TGT AND EARLY TUE MRNG IN UIN
AND COU AND POSSIBLY IN THE STL METRO AREA TUE MRNG AS BOTH NAM
AND GFS MDLS HAVE QPF FCST LT TGT AND TUE MRNG MAINLY N AND W OF
STL. MDL RH FCSTS KEEP THE HIGH BNDRY LYR RH N AND W OF THE TAF
SITES LT TGT...ALTHOUGH THE PREVAILING CEILING HGTS SHOULD LWR LT
TGT INTO TUE AT THE TAF SITES. WILL KEEP THE PREVAILING CIG HGTS
ABV MVFR AND LEAN TWD THE MORE OPTIMISTIC CEILING HGT FCST OF THE
ETA MOS AS THE GFS AND ESPECIALLY THE NGM MOS CIG HGT FCST CONT TO
APR TOO LOW. MDL TIME HGT SECTIONS OF RH SHOW PLENTY OF RH ARND
700 MB LT TGT AND TUE MRNG...THEN INCRSG BNDRY LYR RH TUE EVNG.
GKS
&&
.LSX WATCHES/WARNINGS/ADVISORIES...
MO...NONE.
IL...NONE.
&&
$$
WFO LSX
FXUS63 KLSX 281213
AFDLSX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE ST LOUIS MO
600 AM CST TUE NOV 28 2006
.DISCUSSION...
...MAJOR WINTER STORM TO AFFECT REGION THURSDAY AND THURSDAY NIGHT...
THE UNSEASONABLY WARM WEATHER OF LATE WILL BE REPLACED WITH MORE
WINTER LIKE TEMPERATURES AS A POWERFUL COLD FRONT IS POISED TO
MOVE ACROSS THE REGION WEDNESDAY NIGHT AND THURSDAY. INITIALLY THE
COLD AIR WILL BE SHALLOW BEHIND THE FRONT...LEADING TO
PRECIPITATION TYPE ISSUES AS MODEL GUIDANCE DEPICTS QUITE A BIT OF
POSTFRONTAL QPF. INITIALLY A FREEZING RAIN AND SLEET MIXTURE WILL
OCCUR...BUT AS THE ARCTIC AIR MASS BUILDS ACROSS THE REGION
THURSDAY AFTERNOON AND EVENING...THE WINTRY MIX WILL TURN TO SNOW
FROM WEST TO EAST AS A DEFORMATION ZONE SETS UP ACROSS THE REGION.
SIGNIFICANT ICE AND SNOW ACCUMULATIONS WILL OCCUR WITH THIS STORM
SYSTEM...THE ONLY REAL QUESTION IS EXACTLY WHERE?
CWA TO REMAIN IN WARM SECTOR AND SOUTHWEST FLOW ALOFT THROUGH
WEDNESDAY WITH ABOVE NORMAL TEMPERATURE REGIME CONTINUING. GIVEN
WARM CONVEYOR BELT IS ALREADY WELL ESTABILISHED WITH GULF WIDE
OPEN...ANY SHORTWAVE RIPPLING ALONG WILL CAUSE SHOWERS AND
THUNDERSTORMS TO DEVELOP. SIMILAR TO WHAT IS OCCURRING EARLY THIS
MORNING.
SURE THERE ARE DIFFERENCES IN THE EXACT TIMING OF THE FRONT AND
DEPTH OF COLD AIR BETWEEN THE GFS AND NAM...BUT I WOULD EXPECT THAT
IN A 48HR MODEL FORECAST. THE BOTTOM LINE IS...BOTH MODELS REVEAL
THE POTENTIAL FOR A SIGNIFICANT ICING EVENT ON THURSDAY FOLLOWED
BY A CLASSIC HEAVY SNOW SCENARIO FOR THURSDAY NIGHT AS A WAVE OF
LOW PRESSURE DEVELOPS ALONG THE FRONTAL BOUNDARY AND MOVES SOUTH
AND THEN EAST OF THE CWA.
THE DETAILS OF THIS FORECAST CLOSELY FOLLOW THE NAM...GIVEN ITS
ABILITY TO CAPTURE AND FORECAST THE THERMODYNAMIC STRUCTURE OF THE
THOSE LOWEST AND MOST CRITICAL LAYERS OF THE ATMOSPHERE.
PLAN ON UPDATING THE SPECIAL WEATHER STATEMENT...AND INCLUDE STRONG
WORDING IN THE HWO THIS MORNING. BEING AS SYSTEM WILL NOT AFFECT THE
CWA UNTIL 5TH AND 6TH PERIOD...FEEL IT IS A LITTLE PREMATURE TO
ISSUE A WINTER STORM WATCH
CVKING
&&
.AVIATION...
FOR THE 12Z TAFS...
LOW LEVEL SOUTHERLY WINDS CONTINUE ACROSS THE AREA THIS MORNING
AROUND HIGH PRESSURE OVER THE EASTERN U.S. THIS PATTERN WILL
CONTINUE THROUGH 12Z WEDNESDAY. AN ARCTIC COLD FRONT IS FORECAST TO
EXTEND FROM CENTRAL WI ACROSS NORTHWEST MO AT THAT TIME. VFR
CONDITIONS ARE EXPECTED TO CONTINUE DURING THE DAY TODAY BEFORE
LOWERING TO MVFR CATEGORY TONIGHT. SCATTERED SHOWERS AND
THUNDERSTORMS WILL MOVE ACROSS THE AREA TODAY AND TONIGHT.
&&
.LSX WATCHES/WARNINGS/ADVISORIES...
MO...NONE.
IL...NONE.
&&
$$
WFO LSX
FXUS63 KLSX 282346
AFDLSX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE ST LOUIS MO
546 PM CST TUE NOV 28 2006
.DISCUSSION...
MODEL SOLNS ARE STILL POINTING TO ADVERSE WINTER WEATHER FOR OUR
AREA LATE WED THRU THU NGT... BUT TRYING TO PIN DOWN EXACT TRENDS
CONTS TO BE VRY FRUSTRATING. SHORT RANGE MODEL SOLNS HV COME TO
SOME CONSENSUS ABT THE POSITION/TIMING OF THE ARCTIC FNT AND THE
INITIAL SURGE OF THE COLD AIR...BUT OTHER DETAILS FOR THIS EVENT ARE
STILL ALL OVER THE PLACE. HOPEFULLY...WITH MORE RELIABLE UA DATA
FROM THE SYSTEM GETTING INTO THE 00Z RUNS THE SPECIFICS WL BEGIN
TO COME TOGETHER.
WE STILL HAVE 18-36 HOURS OF UNSEASONABLY MILD WX BFR THE LEADING
EDGE OF THE COLD AIR BGNS TO IMPACT THE REGION. AMS TNGT RMNS
WKLY UNSTBL BUT THERE APRS TO BE LTL IN THE WAY OF FORCING...SO HV
CONTD ONLY LO POPS ACR AREA. POPS SHUD JUMP INTO THE LIKELY CAT
ON WED OVR NW HLF OF FA WHERE FNT WL INTERACT WITH THE INCRG
UNSTBL AMS. MODELS OVR THE PAST FEW DAYS HV REALLY BEEN LIMITING
INSTABILITY ALG/AHD OF FNT. NAM IS NOW FCSTG MUCAPES INTO THE
1000-1500 J/KG RANGE BY WED AFTN...AND THERE IS CERTAINLY A WINDOW
OF SVRWX POTENTIAL IN THIS RLTVLY LO CAPE/HI SHEAR COOL SEASON
ENVIRONMENT.
WINTRY MIX SHUD DVLP LATE WED NGT OVR N AREAS AS TEMPS FALL BLO
FRZG...WITH THE ICING AREA ADV S ON THU WITH THE 32 DEGREE
ISOTHERM. IN MOST AREAS...THE POST FRONTAL RAIN/DRZL SHUD FIRST
CHG TO FRZG RAIN...THEN BCM MIXED WITH SLEET..BFR CHGG TO ALL
SNOW.
AMT OF PCPN IN THE COLDER AIR AND PCPN TYPE IS THE FIRST POINT OF
CONTENTION IN THE MODEL SOLNS. NAM IS XTRMLY BULLISH WITH THE
PCPN IN THE COLD AIR...WHILE THE GFS IS NOW RPDLY SHUTTING DOWN
THE PCPN SHORTLY AFTER THE ARRIVAL OF THE COLD AIR. DON'T REALLY
UNDERSTAND WHY THE GFS...WHICH HAD ALSO BEEN ROBUST WITH THE PCPN IN
THE COLD AIR...HAS SUDDENLY "GONE DRY" ON THE 06Z AND 12Z
RUNS...BUT I AM SUSPICIOUS OF THIS GIVEN THE WAY THE TROF IS
LAGGING THE FRONT.
THE SECOND PROBLEM IS HOW STG THE UPR SYS WL BE WHEN IT LIFTS OUT.
AGAIN...THE GFS AS WKND THIS FTR SINCE THE RUNS OF YSTDA...WHILE
THE NAM...ECMWF...AND UKMET ARE ALL MORE INTS WITH LO. MORE INTS SOLN
WULD SUGGEST A SWATH OF POTENTIALL HVY SNW DVLPG...AFTER THE
INITIAL SHOT OF ICING...SOMEWHERE OVR THE SE 2/3 OF THE FA THU
AFTN AND THU NGT.
AFT MUCH ANALYSIS...OPTED TO LEAN TWD THE NAM SOLNS...ALBEIT WITH
SMWHAT LESS QPF...AND WITH A BIT LONGER PD OF MIXED PCPN. IF THE
MORE AMPLIFIED SOLN VERIFIES...WHICH SEEMS TO BE THE MODEL
CONSENSUS...WRM AIR ABV SUB FREEZING SFC AIR SHUD HANG ON A BIT
LONGER CAUSING THE ZR/IP TO LINGER. AND LEANING TWD THE NAM AND
MORE AMPLIFIED SOLNS ALSO MEANS A BTR THRT OF SGFNT SNW ACCUM AFT
THE AMS COOLS ENUF TO SUPPORT ALL SNOW.
ONE VRY DISTURBING ASPECT OF THE MODEL OUTPUT IS THAT NAM...AND TO
A LESSER EXTENT THE GFS...ARE SUGGESTING SOME JET COUPLING BTWN
WIND MAX DVLPG OVR AR AND JET CORE OVR UPR GTLKS...ARND 00Z FRI. VRY
STG DIVERGENCE IS BULLSEYED OVR THE CWA...WITH 85H TEMPS OF -2 TO
-5...WHICH ARE OFTEN INDICATIVE OF HVY SNOW...NR THE I-44 AND
I-70 CORRIDORS.
ALTHO THERE IS STILL MUCH UNCERTAINTY...BLV THAT THE THREAT OF
A SGFNT WINTER STORM IS HIGH ENUF THAT ISSUANCE OF A WINTER STORM
WATCH IS WARRANTED...AND THIS WAS ISSUED SHORTLY AFTER 4 PM.
PCPN SHUD WIND DOWN LTR THU NGT AS UPR SYSTEM ROLLS INTO OHIO
VLY. FRIDAY AND THE START OF THE WEEKEND WL BE CHILLY BUT DRY AS
HEART OF THE COLD AIR MOVES THROUGH...THEN EXPECT TEMPERATURES TO
SLOWLY MODERATE HEADING INTO THE FIRST PART OF THE NEW WEEK.
TRUETT
&&
.AVIATION...
FOR THE 18Z TAFS...
GUIDANCE HAS BEEN OVER-DOING THE LOW LEVEL RELATIVE HUMIDITY A BIT
THE LAST FEW DAYS...BUT I THINK IT MIGHT BE THE DAY TO GO AHEAD
AND START MARGINAL CIGS IN THE FORECAST. THERE'S A PRETTY LARGE
AREA OF MARGINAL AND INSTRUMENT CONDITIONS SOUTH OF THE AREA IN
OKLAHOMA AND ARKANSAS...AND INCREASING FLOW AHEAD OF THE
WEDNESDAY/THURSDAY FROPA SHOULD BE ENOUGH TO FINALLY DRAG THOSE
CIGS NORTHWARD INTO OUR AREA. ALREADY SEEING MARGINAL CONDITIONS
IN PARTS OF WESTERN MISSOURI...SO THIS LOOKS LIKE A DECENT
ASSUMPTION. ISOLATED/WIDELY SCATTERED SHOWERS WILL LIKELY CONTINUE
THROUGH WEDNESDAY MORNING...THEN COVERAGE WILL PROBABLY INCREASE
AS THE COLD FRONT APPROACHES THE AREA.
CARNEY
&&
.LSX WATCHES/WARNINGS/ADVISORIES...
MO...WINTER STORM WATCH FROM THURSDAY MORNING THROUGH LATE THURSDAY
NIGHT FOR AUDRAIN-BOONE-CALLAWAY-COLE-CRAWFORD-FRANKLIN-
GASCONADE-IRON-JEFFERSON-LINCOLN-MADISON-MONITEAU-
MONTGOMERY-OSAGE-PIKE-RALLS-REYNOLDS-ST. CHARLES-ST.
FRANCOIS-ST. LOUIS-ST. LOUIS CITY-STE. GENEVIEVE-WARREN-
WASHINGTON.
WINTER STORM WATCH FROM LATE WEDNESDAY NIGHT THROUGH THURSDAY
AFTERNOON FOR KNOX-LEWIS-MARION-MONROE-SHELBY.
IL...WINTER STORM WATCH FROM THURSDAY MORNING THROUGH LATE THURSDAY
NIGHT FOR BOND IL-CALHOUN IL-CLINTON IL-FAYETTE IL-GREENE
IL-JERSEY IL-MACOUPIN IL-MADISON IL-MARION IL-MONROE IL-
MONTGOMERY IL-PIKE IL-RANDOLPH IL-ST. CLAIR IL-WASHINGTON
IL.
WINTER STORM WATCH FROM LATE WEDNESDAY NIGHT THROUGH THURSDAY
AFTERNOON FOR ADAMS IL-BROWN IL.
&&
$$
WFO LSX
FXUS63 KLSX 290006
AFDLSX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE ST LOUIS MO
608 PM CST TUE NOV 28 2006
.DISCUSSION...
MODEL SOLNS ARE STILL POINTING TO ADVERSE WINTER WEATHER FOR OUR
AREA LATE WED THRU THU NGT... BUT TRYING TO PIN DOWN EXACT TRENDS
CONTS TO BE VRY FRUSTRATING. SHORT RANGE MODEL SOLNS HV COME TO
SOME CONSENSUS ABT THE POSITION/TIMING OF THE ARCTIC FNT AND THE
INITIAL SURGE OF THE COLD AIR...BUT OTHER DETAILS FOR THIS EVENT ARE
STILL ALL OVER THE PLACE. HOPEFULLY...WITH MORE RELIABLE UA DATA
FROM THE SYSTEM GETTING INTO THE 00Z RUNS THE SPECIFICS WL BEGIN
TO COME TOGETHER.
WE STILL HAVE 18-36 HOURS OF UNSEASONABLY MILD WX BFR THE LEADING
EDGE OF THE COLD AIR BGNS TO IMPACT THE REGION. AMS TNGT RMNS
WKLY UNSTBL BUT THERE APRS TO BE LTL IN THE WAY OF FORCING...SO HV
CONTD ONLY LO POPS ACR AREA. POPS SHUD JUMP INTO THE LIKELY CAT
ON WED OVR NW HLF OF FA WHERE FNT WL INTERACT WITH THE INCRG
UNSTBL AMS. MODELS OVR THE PAST FEW DAYS HV REALLY BEEN LIMITING
INSTABILITY ALG/AHD OF FNT. NAM IS NOW FCSTG MUCAPES INTO THE
1000-1500 J/KG RANGE BY WED AFTN...AND THERE IS CERTAINLY A WINDOW
OF SVRWX POTENTIAL IN THIS RLTVLY LO CAPE/HI SHEAR COOL SEASON
ENVIRONMENT.
WINTRY MIX SHUD DVLP LATE WED NGT OVR N AREAS AS TEMPS FALL BLO
FRZG...WITH THE ICING AREA ADV S ON THU WITH THE 32 DEGREE
ISOTHERM. IN MOST AREAS...THE POST FRONTAL RAIN/DRZL SHUD FIRST
CHG TO FRZG RAIN...THEN BCM MIXED WITH SLEET..BFR CHGG TO ALL
SNOW.
AMT OF PCPN IN THE COLDER AIR AND PCPN TYPE IS THE FIRST POINT OF
CONTENTION IN THE MODEL SOLNS. NAM IS XTRMLY BULLISH WITH THE
PCPN IN THE COLD AIR...WHILE THE GFS IS NOW RPDLY SHUTTING DOWN
THE PCPN SHORTLY AFTER THE ARRIVAL OF THE COLD AIR. DON'T REALLY
UNDERSTAND WHY THE GFS...WHICH HAD ALSO BEEN ROBUST WITH THE PCPN IN
THE COLD AIR...HAS SUDDENLY "GONE DRY" ON THE 06Z AND 12Z
RUNS...BUT I AM SUSPICIOUS OF THIS GIVEN THE WAY THE TROF IS
LAGGING THE FRONT.
THE SECOND PROBLEM IS HOW STG THE UPR SYS WL BE WHEN IT LIFTS OUT.
AGAIN...THE GFS AS WKND THIS FTR SINCE THE RUNS OF YSTDA...WHILE
THE NAM...ECMWF...AND UKMET ARE ALL MORE INTS WITH LO. MORE INTS SOLN
WULD SUGGEST A SWATH OF POTENTIALL HVY SNW DVLPG...AFTER THE
INITIAL SHOT OF ICING...SOMEWHERE OVR THE SE 2/3 OF THE FA THU
AFTN AND THU NGT.
AFT MUCH ANALYSIS...OPTED TO LEAN TWD THE NAM SOLNS...ALBEIT WITH
SMWHAT LESS QPF...AND WITH A BIT LONGER PD OF MIXED PCPN. IF THE
MORE AMPLIFIED SOLN VERIFIES...WHICH SEEMS TO BE THE MODEL
CONSENSUS...WRM AIR ABV SUB FREEZING SFC AIR SHUD HANG ON A BIT
LONGER CAUSING THE ZR/IP TO LINGER. AND LEANING TWD THE NAM AND
MORE AMPLIFIED SOLNS ALSO MEANS A BTR THRT OF SGFNT SNW ACCUM AFT
THE AMS COOLS ENUF TO SUPPORT ALL SNOW.
ONE VRY DISTURBING ASPECT OF THE MODEL OUTPUT IS THAT NAM...AND TO
A LESSER EXTENT THE GFS...ARE SUGGESTING SOME JET COUPLING BTWN
WIND MAX DVLPG OVR AR AND JET CORE OVR UPR GTLKS...ARND 00Z FRI. VRY
STG DIVERGENCE IS BULLSEYED OVR THE CWA...WITH 85H TEMPS OF -2 TO
-5...WHICH ARE OFTEN INDICATIVE OF HVY SNOW...NR THE I-44 AND
I-70 CORRIDORS.
ALTHO THERE IS STILL MUCH UNCERTAINTY...BLV THAT THE THREAT OF
A SGFNT WINTER STORM IS HIGH ENUF THAT ISSUANCE OF A WINTER STORM
WATCH IS WARRANTED...AND THIS WAS ISSUED SHORTLY AFTER 4 PM.
PCPN SHUD WIND DOWN LTR THU NGT AS UPR SYSTEM ROLLS INTO OHIO
VLY. FRIDAY AND THE START OF THE WEEKEND WL BE CHILLY BUT DRY AS
HEART OF THE COLD AIR MOVES THROUGH...THEN EXPECT TEMPERATURES TO
SLOWLY MODERATE HEADING INTO THE FIRST PART OF THE NEW WEEK.
TRUETT
&&
.AVIATION...
FOR THE 00Z TAFS...
APPROACHING COLD FRONT REMAINS WELL TO THE WEST OF THE CWA AS OF
23Z...SO TAF SITES TO BE IN WARM SECTOR FOR MOST OF FORECAST PERIOD.
AS FOR CIGS...THEY WILL REMAIN MVFR TIL FRONTAL PASSAGE. WENT WITH
NAM TIMING WITH FRONT MOVING THRU KUIN BY 19Z AND THRU KCOU BY
22Z...WHILE FRONT WILL NOT MOVE THRU KSUS/KSTL TIL AFTER 00Z THU.
BEHIND FRONT WILL SEE CIGS DROP TO IFR AT TIMES. PCPN TO REMAIN
RATHER SCATTERED IN NATURE TIL MIDDAY ON WED...WITH CONVECTIVE
ACTIVITY PICKING UP AHEAD OF COLD FRONT...WITH BEST CHANCES OF TRWS
FOR SITES ALONG I-70 CORRIDOR...KCOU BY 16Z AND KSUS/KSTL BY 20Z.
BYRD
&&
.LSX WATCHES/WARNINGS/ADVISORIES...
MO...WINTER STORM WATCH FROM THURSDAY MORNING THROUGH LATE THURSDAY
NIGHT FOR AUDRAIN-BOONE-CALLAWAY-COLE-CRAWFORD-FRANKLIN-
GASCONADE-IRON-JEFFERSON-LINCOLN-MADISON-MONITEAU-
MONTGOMERY-OSAGE-PIKE-RALLS-REYNOLDS-ST. CHARLES-ST.
FRANCOIS-ST. LOUIS-ST. LOUIS CITY-STE. GENEVIEVE-WARREN-
WASHINGTON.
WINTER STORM WATCH FROM LATE WEDNESDAY NIGHT THROUGH THURSDAY
AFTERNOON FOR KNOX-LEWIS-MARION-MONROE-SHELBY.
IL...WINTER STORM WATCH FROM THURSDAY MORNING THROUGH LATE THURSDAY
NIGHT FOR BOND IL-CALHOUN IL-CLINTON IL-FAYETTE IL-GREENE
IL-JERSEY IL-MACOUPIN IL-MADISON IL-MARION IL-MONROE IL-
MONTGOMERY IL-PIKE IL-RANDOLPH IL-ST. CLAIR IL-WASHINGTON
IL.
WINTER STORM WATCH FROM LATE WEDNESDAY NIGHT THROUGH THURSDAY
AFTERNOON FOR ADAMS IL-BROWN IL.
&&
$$
WFO LSX
FXUS63 KLSX 290505
AFDLSX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE ST LOUIS MO
1106 PM CST TUE NOV 28 2006
.DISCUSSION...
MODEL SOLNS ARE STILL POINTING TO ADVERSE WINTER WEATHER FOR OUR
AREA LATE WED THRU THU NGT... BUT TRYING TO PIN DOWN EXACT TRENDS
CONTS TO BE VRY FRUSTRATING. SHORT RANGE MODEL SOLNS HV COME TO
SOME CONSENSUS ABT THE POSITION/TIMING OF THE ARCTIC FNT AND THE
INITIAL SURGE OF THE COLD AIR...BUT OTHER DETAILS FOR THIS EVENT ARE
STILL ALL OVER THE PLACE. HOPEFULLY...WITH MORE RELIABLE UA DATA
FROM THE SYSTEM GETTING INTO THE 00Z RUNS THE SPECIFICS WL BEGIN
TO COME TOGETHER.
WE STILL HAVE 18-36 HOURS OF UNSEASONABLY MILD WX BFR THE LEADING
EDGE OF THE COLD AIR BGNS TO IMPACT THE REGION. AMS TNGT RMNS
WKLY UNSTBL BUT THERE APRS TO BE LTL IN THE WAY OF FORCING...SO HV
CONTD ONLY LO POPS ACR AREA. POPS SHUD JUMP INTO THE LIKELY CAT
ON WED OVR NW HLF OF FA WHERE FNT WL INTERACT WITH THE INCRG
UNSTBL AMS. MODELS OVR THE PAST FEW DAYS HV REALLY BEEN LIMITING
INSTABILITY ALG/AHD OF FNT. NAM IS NOW FCSTG MUCAPES INTO THE
1000-1500 J/KG RANGE BY WED AFTN...AND THERE IS CERTAINLY A WINDOW
OF SVRWX POTENTIAL IN THIS RLTVLY LO CAPE/HI SHEAR COOL SEASON
ENVIRONMENT.
WINTRY MIX SHUD DVLP LATE WED NGT OVR N AREAS AS TEMPS FALL BLO
FRZG...WITH THE ICING AREA ADV S ON THU WITH THE 32 DEGREE
ISOTHERM. IN MOST AREAS...THE POST FRONTAL RAIN/DRZL SHUD FIRST
CHG TO FRZG RAIN...THEN BCM MIXED WITH SLEET..BFR CHGG TO ALL
SNOW.
AMT OF PCPN IN THE COLDER AIR AND PCPN TYPE IS THE FIRST POINT OF
CONTENTION IN THE MODEL SOLNS. NAM IS XTRMLY BULLISH WITH THE
PCPN IN THE COLD AIR...WHILE THE GFS IS NOW RPDLY SHUTTING DOWN
THE PCPN SHORTLY AFTER THE ARRIVAL OF THE COLD AIR. DON'T REALLY
UNDERSTAND WHY THE GFS...WHICH HAD ALSO BEEN ROBUST WITH THE PCPN IN
THE COLD AIR...HAS SUDDENLY "GONE DRY" ON THE 06Z AND 12Z
RUNS...BUT I AM SUSPICIOUS OF THIS GIVEN THE WAY THE TROF IS
LAGGING THE FRONT.
THE SECOND PROBLEM IS HOW STG THE UPR SYS WL BE WHEN IT LIFTS OUT.
AGAIN...THE GFS AS WKND THIS FTR SINCE THE RUNS OF YSTDA...WHILE
THE NAM...ECMWF...AND UKMET ARE ALL MORE INTS WITH LO. MORE INTS SOLN
WULD SUGGEST A SWATH OF POTENTIALL HVY SNW DVLPG...AFTER THE
INITIAL SHOT OF ICING...SOMEWHERE OVR THE SE 2/3 OF THE FA THU
AFTN AND THU NGT.
AFT MUCH ANALYSIS...OPTED TO LEAN TWD THE NAM SOLNS...ALBEIT WITH
SMWHAT LESS QPF...AND WITH A BIT LONGER PD OF MIXED PCPN. IF THE
MORE AMPLIFIED SOLN VERIFIES...WHICH SEEMS TO BE THE MODEL
CONSENSUS...WRM AIR ABV SUB FREEZING SFC AIR SHUD HANG ON A BIT
LONGER CAUSING THE ZR/IP TO LINGER. AND LEANING TWD THE NAM AND
MORE AMPLIFIED SOLNS ALSO MEANS A BTR THRT OF SGFNT SNW ACCUM AFT
THE AMS COOLS ENUF TO SUPPORT ALL SNOW.
ONE VRY DISTURBING ASPECT OF THE MODEL OUTPUT IS THAT NAM...AND TO
A LESSER EXTENT THE GFS...ARE SUGGESTING SOME JET COUPLING BTWN
WIND MAX DVLPG OVR AR AND JET CORE OVR UPR GTLKS...ARND 00Z FRI. VRY
STG DIVERGENCE IS BULLSEYED OVR THE CWA...WITH 85H TEMPS OF -2 TO
-5...WHICH ARE OFTEN INDICATIVE OF HVY SNOW...NR THE I-44 AND
I-70 CORRIDORS.
ALTHO THERE IS STILL MUCH UNCERTAINTY...BLV THAT THE THREAT OF
A SGFNT WINTER STORM IS HIGH ENUF THAT ISSUANCE OF A WINTER STORM
WATCH IS WARRANTED...AND THIS WAS ISSUED SHORTLY AFTER 4 PM.
PCPN SHUD WIND DOWN LTR THU NGT AS UPR SYSTEM ROLLS INTO OHIO
VLY. FRIDAY AND THE START OF THE WEEKEND WL BE CHILLY BUT DRY AS
HEART OF THE COLD AIR MOVES THROUGH...THEN EXPECT TEMPERATURES TO
SLOWLY MODERATE HEADING INTO THE FIRST PART OF THE NEW WEEK.
TRUETT
&&
.AVIATION...
FOR THE 06Z TAFS...
COLD FRONT EXTENDS FROM WRN WI THRU ERN IA AND INTO NWRN MO...THEN
INTO KS AS OF 04Z. HOWEVER...NAM CONTINUES TO SLOW ITS PROGRESS TO
THE E...KEEPING IT WEST OF KUIN AND KCOU TIL THE AFTERNOON HOURS ON
WED. WILL TIME FRONT INTO KUIN BY 22Z AND KCOU BY 23Z. FRONT SHOULD
STAY JUST W OF KSUS/KSTL TIL AFTER 06Z THU. AS FOR CIGS...THEY ARE
ALL OVER THE PLACE...WITH KCOU AND KUIN CLEAR AT THE MOMENT. BUT
WITH FRONT APPROACHING THE AREA...SHOULD SEE CU/SC CONT TO DEVELOP
AND SPREAD EASTWARD OVERNIGHT...WITH MVFR CIG RETURNING BETWEEN 08Z
AND 09Z. IN THE MEANTIME...SC HAS REMAINED OVER ERN MO WITH LOW MVFR
CIGS OVER KSUS/KSTL. WILL RAISE CIGS TO HIGH MVFR DURING THE MORNING
HOURS ON WED FOR THESE FORECAST SITES WITH DAYTIME HEATING. BEHIND
FRONT WILL SEE CIGS DROP TO IFR AT TIMES. PCPN TO REMAIN RATHER
SCATTERED IN NATURE TIL MIDDAY ON WED...WITH CONVECTIVE ACTIVITY
PICKING UP AHEAD OF COLD FRONT...WITH BEST CHANCES OF TRWS FOR SITES
ALONG I-70 CORRIDOR...KCOU BY 20Z AND KSUS/KSTL BY 22Z.
BYRD
&&
.LSX WATCHES/WARNINGS/ADVISORIES...
MO...WINTER STORM WATCH FROM THURSDAY MORNING THROUGH LATE THURSDAY
NIGHT FOR AUDRAIN-BOONE-CALLAWAY-COLE-CRAWFORD-FRANKLIN-
GASCONADE-IRON-JEFFERSON-LINCOLN-MADISON-MONITEAU-
MONTGOMERY-OSAGE-PIKE-RALLS-REYNOLDS-ST. CHARLES-ST.
FRANCOIS-ST. LOUIS-ST. LOUIS CITY-STE. GENEVIEVE-WARREN-
WASHINGTON.
WINTER STORM WATCH FROM LATE WEDNESDAY NIGHT THROUGH THURSDAY
AFTERNOON FOR KNOX-LEWIS-MARION-MONROE-SHELBY.
IL...WINTER STORM WATCH FROM THURSDAY MORNING THROUGH LATE THURSDAY
NIGHT FOR BOND IL-CALHOUN IL-CLINTON IL-FAYETTE IL-GREENE
IL-JERSEY IL-MACOUPIN IL-MADISON IL-MARION IL-MONROE IL-
MONTGOMERY IL-PIKE IL-RANDOLPH IL-ST. CLAIR IL-WASHINGTON
IL.
WINTER STORM WATCH FROM LATE WEDNESDAY NIGHT THROUGH THURSDAY
AFTERNOON FOR ADAMS IL-BROWN IL.
&&
$$
WFO LSX
FXUS63 KLSX 290858
AFDLSX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE ST LOUIS MO
258 AM CST WED NOV 29 2006
.DISCUSSION...
...MAJOR WINTER STORM WILL BEGIN TO AFFECT REGION TONIGHT...
MODEL GUIDANCE HAS COME INTO BETTER AGREEMENT ON LARGE SCALE
FEATURES CONCERNING THE COLD FRONT AND DEVELOPING WINTER STORM
SCENARIO...BUT STILL EXHIBIT SOME DIFFERENCES IN THE DETAILS.
COLD FRONT CURRENTLY EXTENDS FROM NEAR PLEASANT HILL TO KIRKSVILLE
WITH SHOWERS AND THUNDERSTORMS DEVELOPING ALONG AND AHEAD OF THE
FRONT.
STILL BELIEVE NAM IS BEST MODEL TO FOLLOW WHEN FOCUSING ON
THERMODYNAMICS OF THE LOWEST LEVELS OF THE ATMOSPHERE AND HAVE
THEREFORE FOLLOWED ITS TIMING OF THE FRONT AND FREEZING LINE ACROSS
THE CWA AS WELL AS TURNOVER TO SNOW.
THE COLD FRONT WILL CONTINUE TO MOVE SOUTHEAST ACROSS THE CWA DURING
THE NEXT 24 HOURS...USHERING IN THE COLDEST AIR OF THE SEASON. RAIN
WILL BEGIN TO FREEZE ON ELEVATED SURFACES ACROSS NORTHWEST SECTIONS
OF THE CWA AS EARLY AS THIS EVENING WITH FREEZING RAIN BECOMING
LIKELY ACROSS PARTS OF CENTRAL MISSOURI AFTER MIDNIGHT.
FREEZING LINE TO MOVE THROUGH ST. LOUIS METRO AREA AROUND 8 AM ON
THURSDAY WITH THE ENTIRE CWA BELOW FREEZING BY THE LATE AFTERNOON.
AS THE COLD AIR DEEPENS...THE RAIN WILL BEGIN TO MIX WITH SLEET AND
EVENTUALLY TURN TO ALL SNOW BY THURSDAY EVENING. SIGNIFICANT ICE
ACCUMULATIONS...ESPECIALLY ON ELEVATED SURFACES SUCH AS TREES AND
POWERLINES WILL LIKELY OCCUR ACROSS CENTRAL AND EASTERN MISSOURI AS
WELL AS WEST CENTRAL ILLINOIS.
ALL MODELS AGREE THAT A STRONG SHORTWAVE ROUNDING THE BASE OF THE
LARGE SCALE TROF WILL INDUCE CYCLOGENESIS ALONG THE FRONTAL BOUNDARY
WITH A CLASSIC DEFORMATION ZONE SETTING UP ALONG OR JUST NORTH OF
THE I-44 CORRIDOR THURSDAY NIGHT. BUFKIT REVEALS ELEVATED CAPE AND
THEREFORE THE CHANCE OF THUNDERSNOW. HAVE FORECASTED SNOW TOTALS
UP TO 10 INCHES IN A BAND THAT LIES JUST NORTH OF I-44 IN MISSOURI
AND I-70 IN ILLINOIS. WOULD NOT BE SURPRISED TO SEE SOME LOCATIONS
RECEIVE MORE THAN A FOOT IF THUNDER OCCURS.
PLAN ON EXTENDING THE WINTER STORM WATCH FOR TONIGHT TO INCLUDE
CENTRAL MISSOURI...OTHERWISE WILL LET DAYSHIFT GET ONE MORE MODEL
RUN UNDER THERE BELT BEFORE ISSUING WINTER STORM WARNINGS.
WINTER STORM EXITS REGION FRIDAY MORNING WITH COLD TEMPERATURES LEFT
IN ITS WAKE. LOOK FOR SINGLE DIGIT READINGS SATURDAY MORNING AS HIGH
PRESSURE OVER A FRESH SNOW PACK RESULTS IN FAVORABLE RADIATIONAL
COOLING.
CVKING
&&
.AVIATION...
FOR THE 06Z TAFS...
COLD FRONT EXTENDS FROM WRN WI THRU ERN IA AND INTO NWRN MO...THEN
INTO KS AS OF 04Z. HOWEVER...NAM CONTINUES TO SLOW ITS PROGRESS TO
THE E...KEEPING IT WEST OF KUIN AND KCOU TIL THE AFTERNOON HOURS ON
WED. WILL TIME FRONT INTO KUIN BY 22Z AND KCOU BY 23Z. FRONT SHOULD
STAY JUST W OF KSUS/KSTL TIL AFTER 06Z THU. AS FOR CIGS...THEY ARE
ALL OVER THE PLACE...WITH KCOU AND KUIN CLEAR AT THE MOMENT. BUT
WITH FRONT APPROACHING THE AREA...SHOULD SEE CU/SC CONT TO DEVELOP
AND SPREAD EASTWARD OVERNIGHT...WITH MVFR CIG RETURNING BETWEEN 08Z
AND 09Z. IN THE MEANTIME...SC HAS REMAINED OVER ERN MO WITH LOW MVFR
CIGS OVER KSUS/KSTL. WILL RAISE CIGS TO HIGH MVFR DURING THE MORNING
HOURS ON WED FOR THESE FORECAST SITES WITH DAYTIME HEATING. BEHIND
FRONT WILL SEE CIGS DROP TO IFR AT TIMES. PCPN TO REMAIN RATHER
SCATTERED IN NATURE TIL MIDDAY ON WED...WITH CONVECTIVE ACTIVITY
PICKING UP AHEAD OF COLD FRONT...WITH BEST CHANCES OF TRWS FOR SITES
ALONG I-70 CORRIDOR...KCOU BY 20Z AND KSUS/KSTL BY 22Z.
BYRD
&&
.LSX WATCHES/WARNINGS/ADVISORIES...
MO...WINTER STORM WATCH FROM THURSDAY MORNING THROUGH LATE THURSDAY
NIGHT FOR CRAWFORD-FRANKLIN-GASCONADE-IRON-JEFFERSON-
LINCOLN-MADISON-MONTGOMERY-OSAGE-PIKE-REYNOLDS-ST. CHARLES-
ST. FRANCOIS-ST. LOUIS-ST. LOUIS CITY-STE. GENEVIEVE-WARREN-
WASHINGTON.
WINTER STORM WATCH FROM LATE TONIGHT THROUGH LATE THURSDAY NIGHT
FOR AUDRAIN-BOONE-CALLAWAY-COLE-MONITEAU-RALLS.
WINTER STORM WATCH FROM THIS EVENING THROUGH THURSDAY AFTERNOON
FOR KNOX-LEWIS-MARION-MONROE-SHELBY.
IL...WINTER STORM WATCH FROM THURSDAY MORNING THROUGH LATE THURSDAY
NIGHT FOR BOND IL-CALHOUN IL-CLINTON IL-FAYETTE IL-GREENE
IL-JERSEY IL-MACOUPIN IL-MADISON IL-MARION IL-MONROE IL-
MONTGOMERY IL-PIKE IL-RANDOLPH IL-ST. CLAIR IL-WASHINGTON
IL.
WINTER STORM WATCH FROM THIS EVENING THROUGH THURSDAY AFTERNOON
FOR ADAMS IL-BROWN IL.
&&
$$
WFO LSX
FXUS63 KLSX 291103
AFDLSX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE ST LOUIS MO
445 AM CST WED NOV 29 2006
.DISCUSSION...
...MAJOR WINTER STORM WILL BEGIN TO AFFECT REGION TONIGHT...
MODEL GUIDANCE HAS COME INTO BETTER AGREEMENT ON LARGE SCALE
FEATURES CONCERNING THE COLD FRONT AND DEVELOPING WINTER STORM
SCENARIO...BUT STILL EXHIBIT SOME DIFFERENCES IN THE DETAILS.
COLD FRONT CURRENTLY EXTENDS FROM NEAR PLEASANT HILL TO KIRKSVILLE
WITH SHOWERS AND THUNDERSTORMS DEVELOPING ALONG AND AHEAD OF THE
FRONT.
STILL BELIEVE NAM IS BEST MODEL TO FOLLOW WHEN FOCUSING ON
THERMODYNAMICS OF THE LOWEST LEVELS OF THE ATMOSPHERE AND HAVE
THEREFORE FOLLOWED ITS TIMING OF THE FRONT AND FREEZING LINE ACROSS
THE CWA AS WELL AS TURNOVER TO SNOW.
THE COLD FRONT WILL CONTINUE TO MOVE SOUTHEAST ACROSS THE CWA DURING
THE NEXT 24 HOURS...USHERING IN THE COLDEST AIR OF THE SEASON. RAIN
WILL BEGIN TO FREEZE ON ELEVATED SURFACES ACROSS NORTHWEST SECTIONS
OF THE CWA AS EARLY AS THIS EVENING WITH FREEZING RAIN BECOMING
LIKELY ACROSS PARTS OF CENTRAL MISSOURI AFTER MIDNIGHT.
FREEZING LINE TO MOVE THROUGH ST. LOUIS METRO AREA AROUND 8 AM ON
THURSDAY WITH THE ENTIRE CWA BELOW FREEZING BY THE LATE AFTERNOON.
AS THE COLD AIR DEEPENS...THE RAIN WILL BEGIN TO MIX WITH SLEET AND
EVENTUALLY TURN TO ALL SNOW BY THURSDAY EVENING. SIGNIFICANT ICE
ACCUMULATIONS...ESPECIALLY ON ELEVATED SURFACES SUCH AS TREES AND
POWERLINES WILL LIKELY OCCUR ACROSS CENTRAL AND EASTERN MISSOURI AS
WELL AS WEST CENTRAL ILLINOIS.
ALL MODELS AGREE THAT A STRONG SHORTWAVE ROUNDING THE BASE OF THE
LARGE SCALE TROF WILL INDUCE CYCLOGENESIS ALONG THE FRONTAL BOUNDARY
WITH A CLASSIC DEFORMATION ZONE SETTING UP ALONG OR JUST NORTH OF
THE I-44 CORRIDOR THURSDAY NIGHT. BUFKIT REVEALS ELEVATED CAPE AND
THEREFORE THE CHANCE OF THUNDERSNOW. HAVE FORECASTED SNOW TOTALS
UP TO 10 INCHES IN A BAND THAT LIES JUST NORTH OF I-44 IN MISSOURI
AND I-70 IN ILLINOIS. WOULD NOT BE SURPRISED TO SEE SOME LOCATIONS
RECEIVE MORE THAN A FOOT IF THUNDER OCCURS.
PLAN ON EXTENDING THE WINTER STORM WATCH FOR TONIGHT TO INCLUDE
CENTRAL MISSOURI...OTHERWISE WILL LET DAYSHIFT GET ONE MORE MODEL
RUN UNDER THERE BELT BEFORE ISSUING WINTER STORM WARNINGS.
WINTER STORM EXITS REGION FRIDAY MORNING WITH COLD TEMPERATURES LEFT
IN ITS WAKE. LOOK FOR SINGLE DIGIT READINGS SATURDAY MORNING AS HIGH
PRESSURE OVER A FRESH SNOW PACK RESULTS IN FAVORABLE RADIATIONAL
COOLING.
CVKING
&&
.AVIATION...
FOR THE 12Z TAFS...
AN ARCTIC COLD FRONT EXTENDED FROM NORTHEAST IA ACROSS WESTERN MO
INTO THE TX PANHANDLE EARLY THIS MORNING...NEAR A DBQ-IRK-PNC LINE.
THE FRONT WILL CONTINUE TO SAG SLOWLY SOUTHEASTWARD DURING THE
PERIOD. MOST OF THE CONVECTION CONTINUED FROM WEST CENTRAL INTO
NORTHEAST MO. THE SHOWERS/SCATTERED THUNDERSTORMS WERE MOVING TO THE
NORTHEAST. THREE HOURLY SURFACE PRESSURE CHANGE MAP INDICATED A 4 MB
RISE CENTER OVER SOUTHEAST NEB. COLD FRONT WAS MOVING FASTER THAN
THE PREVIOUS MODEL GUIDANCE. THE LATEST NAM GUIDANCE ON BUFKIT
SOUNDINGS INDICATED THE RAIN WOULD CHANGE TO FREEZING RAIN AT UIN
AROUND 09Z TONIGHT AND AT COU AROUND 10Z TONIGHT. THE 00Z RUN OF THE
NAM CHANGED DROPPED THE TEMP TO FREEZING 2 TO 3 HOURS SOONER.
WIDESPREAD IFR CONDITIONS WILL DEVELOP BEHIND THE FRONT AS IT SLIDES
ACROSS THE AREA.
TPS
&&
.LSX WATCHES/WARNINGS/ADVISORIES...
MO...WINTER STORM WATCH FROM THURSDAY MORNING THROUGH LATE THURSDAY
NIGHT FOR CRAWFORD-FRANKLIN-GASCONADE-IRON-JEFFERSON-
LINCOLN-MADISON-MONTGOMERY-OSAGE-PIKE-REYNOLDS-ST. CHARLES-
ST. FRANCOIS-ST. LOUIS-ST. LOUIS CITY-STE. GENEVIEVE-WARREN-
WASHINGTON.
WINTER STORM WATCH FROM LATE TONIGHT THROUGH LATE THURSDAY
NIGHT FOR AUDRAIN-BOONE-CALLAWAY-COLE-MONITEAU-RALLS.
WINTER STORM WATCH FROM THIS EVENING THROUGH THURSDAY AFTERNOON
FOR KNOX-LEWIS-MARION-MONROE-SHELBY.
IL...WINTER STORM WATCH FROM THURSDAY MORNING THROUGH LATE THURSDAY
NIGHT FOR BOND IL-CALHOUN IL-CLINTON IL-FAYETTE IL-GREENE
IL-JERSEY IL-MACOUPIN IL-MADISON IL-MARION IL-MONROE IL-
MONTGOMERY IL-PIKE IL-RANDOLPH IL-ST. CLAIR IL-WASHINGTON
IL.
WINTER STORM WATCH FROM THIS EVENING THROUGH THURSDAY AFTERNOON
FOR ADAMS IL-BROWN IL.
&&
$$
WFO LSX
FXUS63 KLSX 291822
AFDLSX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE ST LOUIS MO
1222 PM CST WED NOV 29 2006
.DISCUSSION...
HAVE UPDATED THE FORECAST TO REFLECT THE FRONT MOVING ACROSS
SLIGHTLY FASTER THAN MODELS HAVE INDICATED. FRONT HAS ALREADY
REACHED A JEFFERSON CITY-PITTSFIELD LINE...WITH TEMPERATURES
QUICKLY DROPPING INTO THE MID 30S BEHIND IT. HAD A FEW SEVERE
THUNDERSTORMS EARLIER...THOUGH THEY HAVE SINCE DIMINISHED. STILL
HAVE THE SLIGHT RISK FOR SVR POTENTIAL AS ENVIRONMENT ALONG AND
AHEAD OF THE FRONT HAS MUCAPES OF 500 J/KG WITH STRONG SHEAR...SO
WILL NEED TO CONTINUE TO WATCH CONVECTIVE TRENDS ALONG AND AHEAD
OF THE FRONT INTO THE NIGHT.
DID NOT CHANGE MUCH FOR TONIGHT OR TOMORROW AT THIS TIME. QUICKER
MOVEMENT OF THE FRONT MAY REQUIRE CHANGE OVER TIMES TO BE MOVED UP
BY A FEW HOURS ON NEXT FORECAST. IN THESE DEEP TROUGH/PARALLEL
LOW LEVEL BOUNDARY SITUATIONS...WILL ALSO BE MONITORING LOCALLY HEAVY
RAINFALL POTENTIAL.
CERTAINTY THAT THERE WILL BE SIGNIFICANT ICE ACCUMULATIONS (1/4 OR
MORE) LATE TONIGHT AND TOMORROW FOLLOW BY SIGNIFICANT SNOW (OVER
6 INCHES) ACCUMULATIONS IS INCREASING...AND WATCHES WILL BE UPGRADED
TO WINTER STORM WARNINGS THIS AFTERNOON.
BRITT
&&
.AVIATION...
FOR THE 18Z TAFS...
COLD FRONT HAS ALREADY MOVED THROUGH KUIN AND KCOU LATE THIS
MORNING WITH A BAND OF SHRA AND SCT TSRA MOVING NEWD ALONG AND
BEHIND THE FRONT. CIGS BEHIND FRONT ARE MAINLY IFR OR LIFR...SO
HAVE GONE WITH THESE CIGS WITH TEMPO GROUPS FOR SHRA. AHEAD OF
THE FRONT...JUST HAVE ISOLD-SCT SHRA ATTM SO HAVE ONLY GONE WITH
VCNTY SHRA. HAVE FRONT MOVG THRU KSUS AND KSTL 03-04Z TIME FRAME.
ALSO HAVE GONE WITH TEMPO GROUP FOR SHRA JUST AHEAD OF THE FRONT
THIS EVENING. FRONT HAS BEEN MOVG A BIT FASTER THAN THE MODELS
HAVE INDICATED...SO HAVE MOVED THE CHANGEOVER TO FZRA AND ALSO THE
CHANGEOVER TO SNPL A FEW HOURS EARLIER.
BRITT
&&
.LSX WATCHES/WARNINGS/ADVISORIES...
MO...WINTER STORM WATCH FROM THURSDAY MORNING THROUGH LATE THURSDAY
NIGHT FOR CRAWFORD-FRANKLIN-GASCONADE-IRON-JEFFERSON-
LINCOLN-MADISON-MONTGOMERY-OSAGE-PIKE-REYNOLDS-ST. CHARLES-
ST. FRANCOIS-ST. LOUIS-ST. LOUIS CITY-STE. GENEVIEVE-WARREN-
WASHINGTON.
WINTER STORM WATCH FROM LATE TONIGHT THROUGH LATE THURSDAY NIGHT
FOR AUDRAIN-BOONE-CALLAWAY-COLE-MONITEAU-RALLS.
WINTER STORM WATCH FROM 6 PM CST THIS EVENING THROUGH THURSDAY
AFTERNOON FOR KNOX-LEWIS-MARION-MONROE-SHELBY.
IL...WINTER STORM WATCH FROM THURSDAY MORNING THROUGH LATE THURSDAY
NIGHT FOR BOND IL-CALHOUN IL-CLINTON IL-FAYETTE IL-GREENE
IL-JERSEY IL-MACOUPIN IL-MADISON IL-MARION IL-MONROE IL-
MONTGOMERY IL-PIKE IL-RANDOLPH IL-ST. CLAIR IL-WASHINGTON
IL.
WINTER STORM WATCH FROM 6 PM CST THIS EVENING THROUGH THURSDAY
AFTERNOON FOR ADAMS IL-BROWN IL.
&&
$$
WFO LSX
FXUS63 KLSX 292248
AFDLSX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE ST LOUIS MO
448 PM CST WED NOV 29 2006
.DISCUSSION...
...MAJOR WINTER STORM WILL AFFECT REGION THROUGH FRIDAY MORNING...
THE 12Z SHORT-TERM MODELS (THRU FRIDAY AFTERNOON)...HAVE COME INTO
BETTER AGREEMENT...ESPECIALLY THE NAM AND GFS...ON HANDLING OF A
MAJOR WINTER STORM TO AFFECT THE AREA...THE FIRST OF THE SEASON.
STARTING WITH TONIGHT...THE MODELS HAVE NOT CORRECTLY ANTICIPATED
THE FORWARD SPEED OF THE ARCTIC CDFNT NOW MOVING THRU OUR AREA...
ROUGHLY ALONG A NEAR KSPI-THRU ST CHARLES COUNTY MO-JUST W OF
KVIH-JUST SE OF KSGF. THE /WEIGHT/ OF THE CD AIR IS FORCING IT
FURTHER S...EVEN WITH STRONG MID LEVEL FLOW TRYING TO TIE IT UP
AHEAD OF A DEVELOPING WAVE OVER ERN OK. WENT AGGRESSIVE AND COLDER
THAN MOS AND MODELS TO ACCOUNT FOR SHARP DROP IN TEMPS BEHIND
FRONT...WITH KIRK ALREADY AT 30F! VAST MAJORITY OF PCPN NOW
DEVELOPING ALG-BEHIND CDFNT OVER SHALLOW ARCTIC AIR IN REGION OF
STRONG RIGHT ENTRANCE REGION LIFT OF H300 JET AND NOSE OF DEVELOPING
H850 JET. THIS STRONG REGION OF LIFT COUPLED WITH FRONTOGENETICAL
FORCING AT MID LEVELS TO GRADUALLY SHIFT FROM THE NWRN HALF OF THE
FA THIS EVENING TO THE SERN HALF LATER TONIGHT. ABNORMALLY HI PWATS
FOR LATE NOVEMBER AND POTENTIAL FOR TRAINING ECHOES AND THUNDER
(ALREADY EXISTING OVER ERN OK THRU NERN MO)...WILL LEAD TO ENHANCED
PCPN TOTALS AND HAVE MENTIONED HEAVY RAINFALL POTENTIAL IN FORECAST.
AS COLD AIR SLOWLY SEEPS INTO THE NWRN FA TONIGHT...WILL SEE RAIN
CHANGE TO FZRA IN THE NWRN THIRD BY LATE TONIGHT.
HEADING INTO THURSDAY...FRONTOGENETICAL PCPN WILL SHIFT TO SERN HALF
OF THE FA AND THEN FADE BY AFTERNOON...ALLOWING FOR A BREAK FOR MOST
AREAS AT SOME POINT FROM LATE MORNING THRU AFTERNOON. BUT NOT
ENTIRELY...AS FZDZ SHOULD BE PREVALENT IN AREAS WITH SUB-FRZG SFC
TEMPS. LOOK FOR 32F ISOTHERM TO PUSH THRU THE STL METRO AREA DURING
LATE MORNING AND EARLY AFTERNOON FROM NW-SE...AND THEN INTO THE SERN
HALF OF THE FA DURING THE AFTERNOON. LOOKING AT SIGNIFICANT ICING
EVENT THRU THURSDAY AFTERNOON...ESPECIALLY IN STRIPE FROM
KVIH-KSTL-K3LF WHERE THIS AREA WILL BE SLOW TO CLEAR OUT FROM
FRONTOGENETICAL PCPN...YET COLD AIR WILL UNDERCUT AS EXPECTED.
FOR THURSDAY NIGHT TIL THE STORM/S CONCLUSION ON FRIDAY MORNING...
MAIN HEAVY SNOW THREAT WILL BE FROM THIS SYSTEM. MODELS HAVE ALL
COME INTO EXCELLENT AGREEMENT ON THE STRENGTH AND TRACK OF THIS
STRONG IMPULSE...NOW EXPECTED TO FORM A CLOSED CIRCULATION BY LATE
THURSDAY AFTERNOON AS H500 CENTER TRACKS JUST S AND E OF KSTL LATE
THURSDAY NIGHT THEN PULLS AWAY FRIDAY MORNING. H700 LO...WHICH HELPS
TO DETERMINE HEAVY PCPN TRACK JUST TO THE LEFT...IS VERY CLOSE TO
THE H500 TRACK. H850 LO...WHICH HELPS TO DETERMINE MAINTENANCE OF
WARM WEDGE OF AIR ALOFT...NOT EXPECTED TO TRACK PAST OUR AREA TIL
LATE THURSDAY EVENING...THEREBY EXPECTING TO KEEP MIXED WINTRY PCPN
IN PLACE FOR THE STL METRO AREA TIL THIS TIME. FURTHER N AND
W...WHEN PCPN RESUMES AROUND SUNSET...SHOULD FALL AS ALL SNOW ALMOST
FROM THE ONSET...AND HEAVY AT TIMES. S AND E OF KSTL...PRESENCE OF
32F ISOTHERM WILL KEEP P-TYPE CALL TOUGH TO A RANGE OF
POSSIBILITIES. LOOKING FOR A STRIPE OF HEAVY SNOW FROM JUST E OF
KCOU-TROY-BOWLING GREEN-PITTSFIELD IL...WHERE NOT ONLY MOST IF NOT
ALL PCPN WILL FALL AS SNOW...BUT ALSO POTENTIAL FOR BANDED SNOW
STRUCTURE AND/OR THUNDERSNOW SUPPORTING MUCH HIGHER SNOWFALL RATES.
FOR NOW HAVE BUMPED UP AMOUNTS TO CLOSE TO A FOOT IN THIS
AREA...TAPERING TO JUST A FEW INCHES IN SERN MO/SRN IL. AS A
RESULT...ALL OF WATCH WILL BE CONVERTED TO A WARNING WITH THIS
PACKAGE EXCEPT IN THE SE EXTREMITY OF THE FA...WHERE LATER ARRIVAL
OF SUB FREEZING TEMPS AND PERSISTENT WARM WEDGE WILL LOWER ICE AND
SNOW AMOUNTS.
TES
FOR PDS STARTING AT 00Z SAT...AT BEGINNING OF THIS PD...MDLS SEEM TO
AGREE RATHER WELL. HOWEVER...MDLS DIVERGE BEGINNING SOON AFT. GFS IS
STGR WITH SRY S/W AT 12Z TUES. GIVEN THE INCONSISTENCIES WITH THE
GFS...AM LEANING TWD AN ECMWF SOLN FOR LOCATION...TIMING OF SYNOPTIC
FEATURES.
ENTR EXTD IS DRY ATTM. THEREFORE...FCST PROBLEM BCMS TEMPS. HAVE
TRENDED TEMPS DOWN IN EXTD PD...ESP FOR SAT. SAT MRNG LOWS SHUD BE
ALLOWED TO FALL INTO LOW TEENS WITH POSS SN PACK AND CLR SKIES. AFT
SAT...TEMPS WILL NOT HAVE A CHC TO REBOUND MUCH. A STG SFC RIDGE
WILL BE IN PLACE WITH GENERALLY A NLY FLOW IN PLACE. SLY FLOW MAY
RETURN FOR A WHILE LATE MON BEFORE ANOTHER CDFNT MVS THRU CWA LATE
TUES. CONFIDENCE IN A FROPA ON TUES IS RATHER LOW DUE TO LACK OF UPR
LVL SUPPORT OF FEATURE. THINKING IS THAT CDFNT WILL STALL N OF CWA
DURING THIS TIME PD...ALLOWING SOME WWA. HOWEVER...AMT OF WRMG IS
UNCERTAIN GIVEN POSSIBLE CLD CVR.
TILLY
&&
.AVIATION...
FOR THE 18Z TAFS...COLD FRONT HAS ALREADY MOVED THROUGH KUIN AND
KCOU LATE THIS MORNING WITH A BAND OF SHRA AND SCT TSRA MOVING
NEWD ALONG AND BEHIND THE FRONT. CIGS BEHIND FRONT ARE MAINLY IFR
OR LIFR...SO HAVE GONE WITH THESE CIGS WITH TEMPO GROUPS FOR SHRA.
AHEAD OF THE FRONT...JUST HAVE ISOLD-SCT SHRA ATTM SO HAVE ONLY
GONE WITH VCNTY SHRA. HAVE FRONT MOVG THRU KSUS AND KSTL 03-04Z
TIME FRAME. ALSO HAVE GONE WITH TEMPO GROUP FOR SHRA JUST AHEAD OF
THE FRONT THIS EVENING. FRONT HAS BEEN MOVG A BIT FASTER THAN THE
MODELS HAVE INDICATED...SO HAVE MOVED THE CHANGEOVER TO FZRA AND
ALSO THE CHANGEOVER TO SNPL A FEW HOURS EARLIER.
BRITT
&&
.LSX WATCHES/WARNINGS/ADVISORIES...
MO...WINTER STORM WARNING FROM 6 AM THURSDAY TO 9 AM CST FRIDAY FOR
CRAWFORD-FRANKLIN-JEFFERSON-ST. CHARLES-ST. LOUIS-ST. LOUIS
CITY-WASHINGTON.
WINTER WEATHER ADVISORY FROM 12 PM THURSDAY TO 9 AM CST FRIDAY
FOR IRON-MADISON-REYNOLDS-ST. FRANCOIS-STE. GENEVIEVE.
WINTER STORM WARNING FROM MIDNIGHT TONIGHT TO 9 AM CST FRIDAY
FOR CALLAWAY-COLE-GASCONADE-LINCOLN-MONITEAU-MONTGOMERY-
OSAGE-PIKE-RALLS-WARREN.
WINTER STORM WARNING UNTIL 9 AM CST FRIDAY FOR AUDRAIN-BOONE-
KNOX-LEWIS-MARION-MONROE-SHELBY.
IL...WINTER STORM WARNING FROM 6 AM THURSDAY TO 9 AM CST FRIDAY FOR
CALHOUN IL-GREENE IL-JERSEY IL-MACOUPIN IL.
WINTER WEATHER ADVISORY FROM 12 PM THURSDAY TO 9 AM CST FRIDAY
FOR CLINTON IL-FAYETTE IL-MARION IL-RANDOLPH IL-WASHINGTON
IL.
WINTER STORM WARNING FROM MIDNIGHT TONIGHT TO 9 AM CST FRIDAY
FOR BROWN IL-PIKE IL.
WINTER STORM WARNING FROM 12 PM THURSDAY TO 9 AM CST FRIDAY FOR
BOND IL-MADISON IL-MONROE IL-MONTGOMERY IL-ST. CLAIR IL.
WINTER STORM WARNING UNTIL 9 AM CST FRIDAY FOR ADAMS IL.
&&
$$
WFO LSX
FXUS63 KLSX 292359
AFDLSX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE ST LOUIS MO
600 PM CST WED NOV 29 2006
.DISCUSSION...
...MAJOR WINTER STORM WILL AFFECT REGION THROUGH FRIDAY MORNING...
THE 12Z SHORT-TERM MODELS (THRU FRIDAY AFTERNOON)...HAVE COME INTO
BETTER AGREEMENT...ESPECIALLY THE NAM AND GFS...ON HANDLING OF A
MAJOR WINTER STORM TO AFFECT THE AREA...THE FIRST OF THE SEASON.
STARTING WITH TONIGHT...THE MODELS HAVE NOT CORRECTLY ANTICIPATED
THE FORWARD SPEED OF THE ARCTIC CDFNT NOW MOVING THRU OUR AREA...
ROUGHLY ALONG A NEAR KSPI-THRU ST CHARLES COUNTY MO-JUST W OF
KVIH-JUST SE OF KSGF. THE /WEIGHT/ OF THE CD AIR IS FORCING IT
FURTHER S...EVEN WITH STRONG MID LEVEL FLOW TRYING TO TIE IT UP
AHEAD OF A DEVELOPING WAVE OVER ERN OK. WENT AGGRESSIVE AND COLDER
THAN MOS AND MODELS TO ACCOUNT FOR SHARP DROP IN TEMPS BEHIND
FRONT...WITH KIRK ALREADY AT 30F! VAST MAJORITY OF PCPN NOW
DEVELOPING ALG-BEHIND CDFNT OVER SHALLOW ARCTIC AIR IN REGION OF
STRONG RIGHT ENTRANCE REGION LIFT OF H300 JET AND NOSE OF DEVELOPING
H850 JET. THIS STRONG REGION OF LIFT COUPLED WITH FRONTOGENETICAL
FORCING AT MID LEVELS TO GRADUALLY SHIFT FROM THE NWRN HALF OF THE
FA THIS EVENING TO THE SERN HALF LATER TONIGHT. ABNORMALLY HI PWATS
FOR LATE NOVEMBER AND POTENTIAL FOR TRAINING ECHOES AND THUNDER
(ALREADY EXISTING OVER ERN OK THRU NERN MO)...WILL LEAD TO ENHANCED
PCPN TOTALS AND HAVE MENTIONED HEAVY RAINFALL POTENTIAL IN FORECAST.
AS COLD AIR SLOWLY SEEPS INTO THE NWRN FA TONIGHT...WILL SEE RAIN
CHANGE TO FZRA IN THE NWRN THIRD BY LATE TONIGHT.
HEADING INTO THURSDAY...FRONTOGENETICAL PCPN WILL SHIFT TO SERN HALF
OF THE FA AND THEN FADE BY AFTERNOON...ALLOWING FOR A BREAK FOR MOST
AREAS AT SOME POINT FROM LATE MORNING THRU AFTERNOON. BUT NOT
ENTIRELY...AS FZDZ SHOULD BE PREVALENT IN AREAS WITH SUB-FRZG SFC
TEMPS. LOOK FOR 32F ISOTHERM TO PUSH THRU THE STL METRO AREA DURING
LATE MORNING AND EARLY AFTERNOON FROM NW-SE...AND THEN INTO THE SERN
HALF OF THE FA DURING THE AFTERNOON. LOOKING AT SIGNIFICANT ICING
EVENT THRU THURSDAY AFTERNOON...ESPECIALLY IN STRIPE FROM
KVIH-KSTL-K3LF WHERE THIS AREA WILL BE SLOW TO CLEAR OUT FROM
FRONTOGENETICAL PCPN...YET COLD AIR WILL UNDERCUT AS EXPECTED.
FOR THURSDAY NIGHT TIL THE STORM/S CONCLUSION ON FRIDAY MORNING...
MAIN HEAVY SNOW THREAT WILL BE FROM THIS SYSTEM. MODELS HAVE ALL
COME INTO EXCELLENT AGREEMENT ON THE STRENGTH AND TRACK OF THIS
STRONG IMPULSE...NOW EXPECTED TO FORM A CLOSED CIRCULATION BY LATE
THURSDAY AFTERNOON AS H500 CENTER TRACKS JUST S AND E OF KSTL LATE
THURSDAY NIGHT THEN PULLS AWAY FRIDAY MORNING. H700 LO...WHICH HELPS
TO DETERMINE HEAVY PCPN TRACK JUST TO THE LEFT...IS VERY CLOSE TO
THE H500 TRACK. H850 LO...WHICH HELPS TO DETERMINE MAINTENANCE OF
WARM WEDGE OF AIR ALOFT...NOT EXPECTED TO TRACK PAST OUR AREA TIL
LATE THURSDAY EVENING...THEREBY EXPECTING TO KEEP MIXED WINTRY PCPN
IN PLACE FOR THE STL METRO AREA TIL THIS TIME. FURTHER N AND
W...WHEN PCPN RESUMES AROUND SUNSET...SHOULD FALL AS ALL SNOW ALMOST
FROM THE ONSET...AND HEAVY AT TIMES. S AND E OF KSTL...PRESENCE OF
32F ISOTHERM WILL KEEP P-TYPE CALL TOUGH TO A RANGE OF
POSSIBILITIES. LOOKING FOR A STRIPE OF HEAVY SNOW FROM JUST E OF
KCOU-TROY-BOWLING GREEN-PITTSFIELD IL...WHERE NOT ONLY MOST IF NOT
ALL PCPN WILL FALL AS SNOW...BUT ALSO POTENTIAL FOR BANDED SNOW
STRUCTURE AND/OR THUNDERSNOW SUPPORTING MUCH HIGHER SNOWFALL RATES.
FOR NOW HAVE BUMPED UP AMOUNTS TO CLOSE TO A FOOT IN THIS
AREA...TAPERING TO JUST A FEW INCHES IN SERN MO/SRN IL. AS A
RESULT...ALL OF WATCH WILL BE CONVERTED TO A WARNING WITH THIS
PACKAGE EXCEPT IN THE SE EXTREMITY OF THE FA...WHERE LATER ARRIVAL
OF SUB FREEZING TEMPS AND PERSISTENT WARM WEDGE WILL LOWER ICE AND
SNOW AMOUNTS.
TES
FOR PDS STARTING AT 00Z SAT...AT BEGINNING OF THIS PD...MDLS SEEM TO
AGREE RATHER WELL. HOWEVER...MDLS DIVERGE BEGINNING SOON AFT. GFS IS
STGR WITH SRY S/W AT 12Z TUES. GIVEN THE INCONSISTENCIES WITH THE
GFS...AM LEANING TWD AN ECMWF SOLN FOR LOCATION...TIMING OF SYNOPTIC
FEATURES.
ENTR EXTD IS DRY ATTM. THEREFORE...FCST PROBLEM BCMS TEMPS. HAVE
TRENDED TEMPS DOWN IN EXTD PD...ESP FOR SAT. SAT MRNG LOWS SHUD BE
ALLOWED TO FALL INTO LOW TEENS WITH POSS SN PACK AND CLR SKIES. AFT
SAT...TEMPS WILL NOT HAVE A CHC TO REBOUND MUCH. A STG SFC RIDGE
WILL BE IN PLACE WITH GENERALLY A NLY FLOW IN PLACE. SLY FLOW MAY
RETURN FOR A WHILE LATE MON BEFORE ANOTHER CDFNT MVS THRU CWA LATE
TUES. CONFIDENCE IN A FROPA ON TUES IS RATHER LOW DUE TO LACK OF UPR
LVL SUPPORT OF FEATURE. THINKING IS THAT CDFNT WILL STALL N OF CWA
DURING THIS TIME PD...ALLOWING SOME WWA. HOWEVER...AMT OF WRMG IS
UNCERTAIN GIVEN POSSIBLE CLD CVR.
TILLY
&&
.AVIATION...
FOR THE 00Z TAFS...COLD FRONT HAS ALREADY MOVED THROUGH KUIN AND
KCOU AND SHOULD MOVE THRU KSUS/KSTL BY 02Z. STILL HAVE VFR/MVFR CIGS
AHEAD OF FRONT...WHILE CIGS BEHIND FRONT ARE MAINLY IFR OR LIFR. AS
FOR PCPN AND TYPE...WILL HAVE RA/TRWS FOR KUIN/KCOU FOR A FEW HOURS
THIS EVENING...THEN SWITCH OVER TO FZRA BY 05Z...THEN BY 10Z WILL
SEE FZRA CHANGE OVER TO A MIX OF PL AND SN...BEFORE TAPERING OFF TO
FZDZ BETWEEN 14Z AND 16Z AS INITIAL SHORTWAVE EXITS REGION. SNOW TO
PICK BACK UP AGAIN FOR KUIN/KCOU BY MID TO LATE AFTERNOON. IN THE
MEANTIME...KSUS/KSTL TO REMAIN LIQUID TIL ABOUT 16Z THU...WITH SOME
TRW ACTIVITY FOR A FEW HOURS BETWEEN 04Z AND 07Z. AFT 16Z...SHOULD
SEE PCPN CHANGE OVER TO FZRA BEFORE TAPERING OFF TO FZDZ BY 19Z.
NEXT WAVE OF ACTIVITY NOT TO AFFECT THESE TWO SITES TIL AFTER THE
CURRENT FORECAST PERIOD.
WINDS TO REMAIN QUITE BLUSTERY FROM THE N AROUND 15KTS WITH GUSTS TO
25KTS AT TIMES.
BYRD
&&
.LSX WATCHES/WARNINGS/ADVISORIES...
MO...WINTER STORM WARNING FROM 6 AM THURSDAY TO 9 AM CST FRIDAY FOR
CRAWFORD-FRANKLIN-JEFFERSON-ST. CHARLES-ST. LOUIS-ST. LOUIS
CITY-WASHINGTON.
WINTER WEATHER ADVISORY FROM 12 PM THURSDAY TO 9 AM CST FRIDAY
FOR IRON-MADISON-REYNOLDS-ST. FRANCOIS-STE. GENEVIEVE.
WINTER STORM WARNING FROM MIDNIGHT TONIGHT TO 9 AM CST FRIDAY
FOR CALLAWAY-COLE-GASCONADE-LINCOLN-MONITEAU-MONTGOMERY-
OSAGE-PIKE-RALLS-WARREN.
WINTER STORM WARNING UNTIL 9 AM CST FRIDAY FOR AUDRAIN-BOONE-
KNOX-LEWIS-MARION-MONROE-SHELBY.
IL...WINTER STORM WARNING FROM 6 AM THURSDAY TO 9 AM CST FRIDAY FOR
CALHOUN IL-GREENE IL-JERSEY IL-MACOUPIN IL.
WINTER WEATHER ADVISORY FROM 12 PM THURSDAY TO 9 AM CST FRIDAY
FOR CLINTON IL-FAYETTE IL-MARION IL-RANDOLPH IL-WASHINGTON
IL.
WINTER STORM WARNING FROM MIDNIGHT TONIGHT TO 9 AM CST FRIDAY
FOR BROWN IL-PIKE IL.
WINTER STORM WARNING FROM 12 PM THURSDAY TO 9 AM CST FRIDAY FOR
BOND IL-MADISON IL-MONROE IL-MONTGOMERY IL-ST. CLAIR IL.
WINTER STORM WARNING UNTIL 9 AM CST FRIDAY FOR ADAMS IL.
&&
$$
WFO LSX
FXUS63 KLSX 300541
AFDLSX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE ST LOUIS MO
1142 PM CST WED NOV 29 2006
.DISCUSSION...
...MAJOR WINTER STORM WILL AFFECT REGION THROUGH FRIDAY MORNING...
THE 12Z SHORT-TERM MODELS (THRU FRIDAY AFTERNOON)...HAVE COME INTO
BETTER AGREEMENT...ESPECIALLY THE NAM AND GFS...ON HANDLING OF A
MAJOR WINTER STORM TO AFFECT THE AREA...THE FIRST OF THE SEASON.
STARTING WITH TONIGHT...THE MODELS HAVE NOT CORRECTLY ANTICIPATED
THE FORWARD SPEED OF THE ARCTIC CDFNT NOW MOVING THRU OUR AREA...
ROUGHLY ALONG A NEAR KSPI-THRU ST CHARLES COUNTY MO-JUST W OF
KVIH-JUST SE OF KSGF. THE /WEIGHT/ OF THE CD AIR IS FORCING IT
FURTHER S...EVEN WITH STRONG MID LEVEL FLOW TRYING TO TIE IT UP
AHEAD OF A DEVELOPING WAVE OVER ERN OK. WENT AGGRESSIVE AND COLDER
THAN MOS AND MODELS TO ACCOUNT FOR SHARP DROP IN TEMPS BEHIND
FRONT...WITH KIRK ALREADY AT 30F! VAST MAJORITY OF PCPN NOW
DEVELOPING ALG-BEHIND CDFNT OVER SHALLOW ARCTIC AIR IN REGION OF
STRONG RIGHT ENTRANCE REGION LIFT OF H300 JET AND NOSE OF DEVELOPING
H850 JET. THIS STRONG REGION OF LIFT COUPLED WITH FRONTOGENETICAL
FORCING AT MID LEVELS TO GRADUALLY SHIFT FROM THE NWRN HALF OF THE
FA THIS EVENING TO THE SERN HALF LATER TONIGHT. ABNORMALLY HI PWATS
FOR LATE NOVEMBER AND POTENTIAL FOR TRAINING ECHOES AND THUNDER
(ALREADY EXISTING OVER ERN OK THRU NERN MO)...WILL LEAD TO ENHANCED
PCPN TOTALS AND HAVE MENTIONED HEAVY RAINFALL POTENTIAL IN FORECAST.
AS COLD AIR SLOWLY SEEPS INTO THE NWRN FA TONIGHT...WILL SEE RAIN
CHANGE TO FZRA IN THE NWRN THIRD BY LATE TONIGHT.
HEADING INTO THURSDAY...FRONTOGENETICAL PCPN WILL SHIFT TO SERN HALF
OF THE FA AND THEN FADE BY AFTERNOON...ALLOWING FOR A BREAK FOR MOST
AREAS AT SOME POINT FROM LATE MORNING THRU AFTERNOON. BUT NOT
ENTIRELY...AS FZDZ SHOULD BE PREVALENT IN AREAS WITH SUB-FRZG SFC
TEMPS. LOOK FOR 32F ISOTHERM TO PUSH THRU THE STL METRO AREA DURING
LATE MORNING AND EARLY AFTERNOON FROM NW-SE...AND THEN INTO THE SERN
HALF OF THE FA DURING THE AFTERNOON. LOOKING AT SIGNIFICANT ICING
EVENT THRU THURSDAY AFTERNOON...ESPECIALLY IN STRIPE FROM
KVIH-KSTL-K3LF WHERE THIS AREA WILL BE SLOW TO CLEAR OUT FROM
FRONTOGENETICAL PCPN...YET COLD AIR WILL UNDERCUT AS EXPECTED.
FOR THURSDAY NIGHT TIL THE STORM/S CONCLUSION ON FRIDAY MORNING...
MAIN HEAVY SNOW THREAT WILL BE FROM THIS SYSTEM. MODELS HAVE ALL
COME INTO EXCELLENT AGREEMENT ON THE STRENGTH AND TRACK OF THIS
STRONG IMPULSE...NOW EXPECTED TO FORM A CLOSED CIRCULATION BY LATE
THURSDAY AFTERNOON AS H500 CENTER TRACKS JUST S AND E OF KSTL LATE
THURSDAY NIGHT THEN PULLS AWAY FRIDAY MORNING. H700 LO...WHICH HELPS
TO DETERMINE HEAVY PCPN TRACK JUST TO THE LEFT...IS VERY CLOSE TO
THE H500 TRACK. H850 LO...WHICH HELPS TO DETERMINE MAINTENANCE OF
WARM WEDGE OF AIR ALOFT...NOT EXPECTED TO TRACK PAST OUR AREA TIL
LATE THURSDAY EVENING...THEREBY EXPECTING TO KEEP MIXED WINTRY PCPN
IN PLACE FOR THE STL METRO AREA TIL THIS TIME. FURTHER N AND
W...WHEN PCPN RESUMES AROUND SUNSET...SHOULD FALL AS ALL SNOW ALMOST
FROM THE ONSET...AND HEAVY AT TIMES. S AND E OF KSTL...PRESENCE OF
32F ISOTHERM WILL KEEP P-TYPE CALL TOUGH TO A RANGE OF
POSSIBILITIES. LOOKING FOR A STRIPE OF HEAVY SNOW FROM JUST E OF
KCOU-TROY-BOWLING GREEN-PITTSFIELD IL...WHERE NOT ONLY MOST IF NOT
ALL PCPN WILL FALL AS SNOW...BUT ALSO POTENTIAL FOR BANDED SNOW
STRUCTURE AND/OR THUNDERSNOW SUPPORTING MUCH HIGHER SNOWFALL RATES.
FOR NOW HAVE BUMPED UP AMOUNTS TO CLOSE TO A FOOT IN THIS
AREA...TAPERING TO JUST A FEW INCHES IN SERN MO/SRN IL. AS A
RESULT...ALL OF WATCH WILL BE CONVERTED TO A WARNING WITH THIS
PACKAGE EXCEPT IN THE SE EXTREMITY OF THE FA...WHERE LATER ARRIVAL
OF SUB FREEZING TEMPS AND PERSISTENT WARM WEDGE WILL LOWER ICE AND
SNOW AMOUNTS.
TES
FOR PDS STARTING AT 00Z SAT...AT BEGINNING OF THIS PD...MDLS SEEM TO
AGREE RATHER WELL. HOWEVER...MDLS DIVERGE BEGINNING SOON AFT. GFS IS
STGR WITH SRY S/W AT 12Z TUES. GIVEN THE INCONSISTENCIES WITH THE
GFS...AM LEANING TWD AN ECMWF SOLN FOR LOCATION...TIMING OF SYNOPTIC
FEATURES.
ENTR EXTD IS DRY ATTM. THEREFORE...FCST PROBLEM BCMS TEMPS. HAVE
TRENDED TEMPS DOWN IN EXTD PD...ESP FOR SAT. SAT MRNG LOWS SHUD BE
ALLOWED TO FALL INTO LOW TEENS WITH POSS SN PACK AND CLR SKIES. AFT
SAT...TEMPS WILL NOT HAVE A CHC TO REBOUND MUCH. A STG SFC RIDGE
WILL BE IN PLACE WITH GENERALLY A NLY FLOW IN PLACE. SLY FLOW MAY
RETURN FOR A WHILE LATE MON BEFORE ANOTHER CDFNT MVS THRU CWA LATE
TUES. CONFIDENCE IN A FROPA ON TUES IS RATHER LOW DUE TO LACK OF UPR
LVL SUPPORT OF FEATURE. THINKING IS THAT CDFNT WILL STALL N OF CWA
DURING THIS TIME PD...ALLOWING SOME WWA. HOWEVER...AMT OF WRMG IS
UNCERTAIN GIVEN POSSIBLE CLD CVR.
TILLY
&&
.AVIATION...
FOR THE 06Z TAFS...COLD FRONT HAS MOVED THROUGH ALL TAF SITES AS OF
05Z. SO CIGS BEHIND FRONT ARE MAINLY IFR OR LIFR. AS FOR PCPN...KUIN
AND KCOU HAVE FALLEN BELOW FREEZING WITH FZRA PERSISTING OVER THE
AREA. SHOULD SEE IT BECOME MIXED WITH SLEET BY MID MORNING...THEN
CHANGE OVER TO SNOW BY 21Z FOR KUIN AND 02Z FOR KCOU. IN THE
MEANTIME...SFC TEMPS TO REMAIN ABOVE FREEZING TIL 19Z FOR KSUS/KSTL.
BY 19Z...LOW LEVEL COLD AIR TO FINALLY MOVE INTO THE AREA CHANGING
PCPN TO FZRA. WILL EVENTUALLY SEE IT CHANGE TO SNOW AT
KSUS/KSTL...BUT AFTER THE END OF THE CURRENT FORECAST PERIOD.
WINDS TO REMAIN QUITE BLUSTERY FROM THE N AROUND 15KTS WITH GUSTS TO
25KTS AT TIMES.
BYRD
&&
.LSX WATCHES/WARNINGS/ADVISORIES...
MO...WINTER STORM WARNING FROM 6 AM THURSDAY TO 9 AM CST FRIDAY FOR
CRAWFORD-FRANKLIN-JEFFERSON-ST. CHARLES-ST. LOUIS-ST. LOUIS
CITY-WASHINGTON.
WINTER WEATHER ADVISORY FROM 12 PM THURSDAY TO 9 AM CST FRIDAY
FOR IRON-MADISON-REYNOLDS-ST. FRANCOIS-STE. GENEVIEVE.
WINTER STORM WARNING FROM MIDNIGHT TONIGHT TO 9 AM CST FRIDAY
FOR CALLAWAY-COLE-GASCONADE-LINCOLN-MONITEAU-MONTGOMERY-
OSAGE-PIKE-RALLS-WARREN.
WINTER STORM WARNING UNTIL 9 AM CST FRIDAY FOR AUDRAIN-BOONE-
KNOX-LEWIS-MARION-MONROE-SHELBY.
IL...WINTER STORM WARNING FROM 6 AM THURSDAY TO 9 AM CST FRIDAY FOR
CALHOUN IL-GREENE IL-JERSEY IL-MACOUPIN IL.
WINTER WEATHER ADVISORY FROM 12 PM THURSDAY TO 9 AM CST FRIDAY
FOR CLINTON IL-FAYETTE IL-MARION IL-RANDOLPH IL-WASHINGTON
IL.
WINTER STORM WARNING FROM MIDNIGHT TONIGHT TO 9 AM CST FRIDAY
FOR BROWN IL-PIKE IL.
WINTER STORM WARNING FROM 12 PM THURSDAY TO 9 AM CST FRIDAY FOR
BOND IL-MADISON IL-MONROE IL-MONTGOMERY IL-ST. CLAIR IL.
WINTER STORM WARNING UNTIL 9 AM CST FRIDAY FOR ADAMS IL.
&&
$$
WFO LSX
FXUS63 KLSX 301037
AFDLSX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE ST LOUIS MO
445 AM CST THU NOV 30 2006
.DISCUSSION...
...MAJOR WINTER STORM WILL AFFECT REGION THROUGH FRIDAY MORNING...
THE 12Z SHORT-TERM MODELS (THRU FRIDAY AFTERNOON)...HAVE COME INTO
BETTER AGREEMENT...ESPECIALLY THE NAM AND GFS...ON HANDLING OF A
MAJOR WINTER STORM TO AFFECT THE AREA...THE FIRST OF THE SEASON.
STARTING WITH TONIGHT...THE MODELS HAVE NOT CORRECTLY ANTICIPATED
THE FORWARD SPEED OF THE ARCTIC CDFNT NOW MOVING THRU OUR AREA...
ROUGHLY ALONG A NEAR KSPI-THRU ST CHARLES COUNTY MO-JUST W OF
KVIH-JUST SE OF KSGF. THE /WEIGHT/ OF THE CD AIR IS FORCING IT
FURTHER S...EVEN WITH STRONG MID LEVEL FLOW TRYING TO TIE IT UP
AHEAD OF A DEVELOPING WAVE OVER ERN OK. WENT AGGRESSIVE AND COLDER
THAN MOS AND MODELS TO ACCOUNT FOR SHARP DROP IN TEMPS BEHIND
FRONT...WITH KIRK ALREADY AT 30F! VAST MAJORITY OF PCPN NOW
DEVELOPING ALG-BEHIND CDFNT OVER SHALLOW ARCTIC AIR IN REGION OF
STRONG RIGHT ENTRANCE REGION LIFT OF H300 JET AND NOSE OF DEVELOPING
H850 JET. THIS STRONG REGION OF LIFT COUPLED WITH FRONTOGENETICAL
FORCING AT MID LEVELS TO GRADUALLY SHIFT FROM THE NWRN HALF OF THE
FA THIS EVENING TO THE SERN HALF LATER TONIGHT. ABNORMALLY HI PWATS
FOR LATE NOVEMBER AND POTENTIAL FOR TRAINING ECHOES AND THUNDER
(ALREADY EXISTING OVER ERN OK THRU NERN MO)...WILL LEAD TO ENHANCED
PCPN TOTALS AND HAVE MENTIONED HEAVY RAINFALL POTENTIAL IN FORECAST.
AS COLD AIR SLOWLY SEEPS INTO THE NWRN FA TONIGHT...WILL SEE RAIN
CHANGE TO FZRA IN THE NWRN THIRD BY LATE TONIGHT.
HEADING INTO THURSDAY...FRONTOGENETICAL PCPN WILL SHIFT TO SERN HALF
OF THE FA AND THEN FADE BY AFTERNOON...ALLOWING FOR A BREAK FOR MOST
AREAS AT SOME POINT FROM LATE MORNING THRU AFTERNOON. BUT NOT
ENTIRELY...AS FZDZ SHOULD BE PREVALENT IN AREAS WITH SUB-FRZG SFC
TEMPS. LOOK FOR 32F ISOTHERM TO PUSH THRU THE STL METRO AREA DURING
LATE MORNING AND EARLY AFTERNOON FROM NW-SE...AND THEN INTO THE SERN
HALF OF THE FA DURING THE AFTERNOON. LOOKING AT SIGNIFICANT ICING
EVENT THRU THURSDAY AFTERNOON...ESPECIALLY IN STRIPE FROM
KVIH-KSTL-K3LF WHERE THIS AREA WILL BE SLOW TO CLEAR OUT FROM
FRONTOGENETICAL PCPN...YET COLD AIR WILL UNDERCUT AS EXPECTED.
FOR THURSDAY NIGHT TIL THE STORM/S CONCLUSION ON FRIDAY MORNING...
MAIN HEAVY SNOW THREAT WILL BE FROM THIS SYSTEM. MODELS HAVE ALL
COME INTO EXCELLENT AGREEMENT ON THE STRENGTH AND TRACK OF THIS
STRONG IMPULSE...NOW EXPECTED TO FORM A CLOSED CIRCULATION BY LATE
THURSDAY AFTERNOON AS H500 CENTER TRACKS JUST S AND E OF KSTL LATE
THURSDAY NIGHT THEN PULLS AWAY FRIDAY MORNING. H700 LO...WHICH HELPS
TO DETERMINE HEAVY PCPN TRACK JUST TO THE LEFT...IS VERY CLOSE TO
THE H500 TRACK. H850 LO...WHICH HELPS TO DETERMINE MAINTENANCE OF
WARM WEDGE OF AIR ALOFT...NOT EXPECTED TO TRACK PAST OUR AREA TIL
LATE THURSDAY EVENING...THEREBY EXPECTING TO KEEP MIXED WINTRY PCPN
IN PLACE FOR THE STL METRO AREA TIL THIS TIME. FURTHER N AND
W...WHEN PCPN RESUMES AROUND SUNSET...SHOULD FALL AS ALL SNOW ALMOST
FROM THE ONSET...AND HEAVY AT TIMES. S AND E OF KSTL...PRESENCE OF
32F ISOTHERM WILL KEEP P-TYPE CALL TOUGH TO A RANGE OF
POSSIBILITIES. LOOKING FOR A STRIPE OF HEAVY SNOW FROM JUST E OF
KCOU-TROY-BOWLING GREEN-PITTSFIELD IL...WHERE NOT ONLY MOST IF NOT
ALL PCPN WILL FALL AS SNOW...BUT ALSO POTENTIAL FOR BANDED SNOW
STRUCTURE AND/OR THUNDERSNOW SUPPORTING MUCH HIGHER SNOWFALL RATES.
FOR NOW HAVE BUMPED UP AMOUNTS TO CLOSE TO A FOOT IN THIS
AREA...TAPERING TO JUST A FEW INCHES IN SERN MO/SRN IL. AS A
RESULT...ALL OF WATCH WILL BE CONVERTED TO A WARNING WITH THIS
PACKAGE EXCEPT IN THE SE EXTREMITY OF THE FA...WHERE LATER ARRIVAL
OF SUB FREEZING TEMPS AND PERSISTENT WARM WEDGE WILL LOWER ICE AND
SNOW AMOUNTS.
TES
FOR PDS STARTING AT 00Z SAT...AT BEGINNING OF THIS PD...MDLS SEEM TO
AGREE RATHER WELL. HOWEVER...MDLS DIVERGE BEGINNING SOON AFT. GFS IS
STGR WITH SRY S/W AT 12Z TUES. GIVEN THE INCONSISTENCIES WITH THE
GFS...AM LEANING TWD AN ECMWF SOLN FOR LOCATION...TIMING OF SYNOPTIC
FEATURES.
ENTR EXTD IS DRY ATTM. THEREFORE...FCST PROBLEM BCMS TEMPS. HAVE
TRENDED TEMPS DOWN IN EXTD PD...ESP FOR SAT. SAT MRNG LOWS SHUD BE
ALLOWED TO FALL INTO LOW TEENS WITH POSS SN PACK AND CLR SKIES. AFT
SAT...TEMPS WILL NOT HAVE A CHC TO REBOUND MUCH. A STG SFC RIDGE
WILL BE IN PLACE WITH GENERALLY A NLY FLOW IN PLACE. SLY FLOW MAY
RETURN FOR A WHILE LATE MON BEFORE ANOTHER CDFNT MVS THRU CWA LATE
TUES. CONFIDENCE IN A FROPA ON TUES IS RATHER LOW DUE TO LACK OF UPR
LVL SUPPORT OF FEATURE. THINKING IS THAT CDFNT WILL STALL N OF CWA
DURING THIS TIME PD...ALLOWING SOME WWA. HOWEVER...AMT OF WRMG IS
UNCERTAIN GIVEN POSSIBLE CLD CVR.
TILLY
&&
.AVIATION...
FOR THE 12Z TAFS...
ARCTIC AIR CONTINUED TO SLIDE INTO THE AREA FROM THE NORTHWEST EARLY
THIS MORNING. FREEZING RAIN CONTINED FROM CENTRAL INTO NORTHEAST MO
WITH RAIN ACROSS THE REMAINDER OF THE REGION. RADAR INDICATED THE
EDGE OF THE PRECIPITATION FROM JUST WEST OF COU TO NEAR UIN. TEMPS
ACROSS THE STL METRO AREA ARE EXPECTED TO SLOWLY DROP DURING THE
MORNING. EXPECT THE TEMP TO REACH THE FREEZING MARK AROUND 16Z WITH
THE FREEZING RAIN BECOMING MIXED WITH SLEET BY LATE AFTERNOON.
EXPECT A MIXTURE OF FREEZING RAIN AND SLEET IN COU AND UIN MUCH OF
THE DAY. BUFKIT SOUNDING FORECAST OFF THE NAM COOLS THE ATMOSPHERE
DOWN AFTER MIDNIGHT AT COU AND UIN TO CHANGE THE PRECIPITATION TO
SNOW.
TPS
&&
.LSX WATCHES/WARNINGS/ADVISORIES...
MO...WINTER STORM WARNING FROM 6 AM THURSDAY TO 9 AM CST FRIDAY FOR
CRAWFORD-FRANKLIN-JEFFERSON-ST. CHARLES-ST. LOUIS-ST. LOUIS
CITY-WASHINGTON.
WINTER WEATHER ADVISORY FROM 12 PM THURSDAY TO 9 AM CST FRIDAY
FOR IRON-MADISON-REYNOLDS-ST. FRANCOIS-STE. GENEVIEVE.
WINTER STORM WARNING FROM MIDNIGHT TONIGHT TO 9 AM CST FRIDAY
FOR CALLAWAY-COLE-GASCONADE-LINCOLN-MONITEAU-MONTGOMERY-
OSAGE-PIKE-RALLS-WARREN.
WINTER STORM WARNING UNTIL 9 AM CST FRIDAY FOR AUDRAIN-BOONE-
KNOX-LEWIS-MARION-MONROE-SHELBY.
IL...WINTER STORM WARNING FROM 6 AM THURSDAY TO 9 AM CST FRIDAY FOR
CALHOUN IL-GREENE IL-JERSEY IL-MACOUPIN IL.
WINTER WEATHER ADVISORY FROM 12 PM THURSDAY TO 9 AM CST FRIDAY
FOR CLINTON IL-FAYETTE IL-MARION IL-RANDOLPH IL-WASHINGTON
IL.
WINTER STORM WARNING FROM MIDNIGHT TONIGHT TO 9 AM CST FRIDAY
FOR BROWN IL-PIKE IL.
WINTER STORM WARNING FROM 12 PM THURSDAY TO 9 AM CST FRIDAY FOR
BOND IL-MADISON IL-MONROE IL-MONTGOMERY IL-ST. CLAIR IL.
WINTER STORM WARNING UNTIL 9 AM CST FRIDAY FOR ADAMS IL.
&&
$$
WFO LSX
FXUS63 KLSX 301120
AFDLSX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE ST LOUIS MO
520 AM CST THU NOV 30 2006
.DISCUSSION...
THE FIRST WINTER STORM OF THE SEASON WILL BE IMPACTING THE BI-
STATE REGION TODAT THROUGH FRIDAY MORNING. THE ARCTIC FRONT HAS
JUST PUSHED SOUTHEAST OF THE CWA ATTM WITH TEMPERATURES CONTINUING
TO FALL BEHIND IT CHANGING THE RAIN TO MAINLY FREEZING RAIN NORTH AND
WEST OF THE ST LOUIS METRO AREA. THE COLD AIR IS ADVANCING FASTER
SOUTHEASTWARD THAN THE MODELS HAD FCST. THE PRECIPITATION HAS
RECENTLY TAPERED OFF OVER THE NORTHWESTERN PORTION OF THE CWA WELL
BEHIND THE ARCTIC COLD FRONT. THE PRECIPITATION SHOULD PICK UP
AGAIN LATE THIS AFTERNOON INTO THE EVENING AS THE MID-UPR LVL LOW
CURRENTLY OVR SERN NM MOVES NORTHEAST THROUGH OK THIS AFTN AND
EVNG TO JUST S OF STL BY 12Z FRI. THE ASSOCIATED SFC LOW WILL MOVE
NEWD THRU AR THIS AFTN AND EVNG TO JUST E OF STL BY 12Z FRI. THE
HEAVIEST SNOW SHOULD OCCUR TGT OVR THE NRN AND WRN PTN OF THE CWA
LEFT OF THE TRACK OF THE MID LVL LOW AND ASSOCIATED 850 MB LOW. IT
APRS THAT THE DEFORMATION ZONE WILL SET UP OVR THE NRN PTN OF THE
CWA LT TGT INTO FRI MRNG WITH A TOTAL OF NR ONE FOOT OF SNOW
ACCUMULATION POSSIBLE. FURTHER S AND E INCLUDING THE STL METRO
AREA ICE ACCUMULATION WILL BE THE MAIN CONCERN TODAY AND THIS
EVENING AS THE STG SLY LLJ AHD OF THE 850 MB LOW BRINGS VRY STG
WAA AND ABUNDANT MOISTURE OVR THE COLD BLW FREEZING SFC LYR
RESULTING IN FREEZING RAIN AND SLEET ACCUMULATION. THE FCST
SOUNDINGS DEPICT THIS ELEVATED WRM LYR OVR THE SUBFREEZING SFC LYR
WHICH SHOULD RESULT IN ICE ACCUMULATION INITIALLY ON ELEVATED
SFCS...TREES AND POWER LINES THEN EVENTUALLY ON THE GROUND AND
ROAD SFC AS THE SFC AND GROUND TEMPERATURE CONTS TO LWR. STG WNDS
TDA AND TGT WILL ONLY AGGREVATE THE SITUATION LEADING TO BLOWING
AND DRIFTING SNOW TGT INTO FRI ESPECIALLY N AND W OF STL...AND
ALSO POSSIBLY LEADING TO DOWNED TREES AND POWER LINES DUE TO THE
COMBINATION OF THE WEIGHT OF THE ICE ACCUMULATION AND THE STRONG
WIND GUSTS. THE SNOW SHOULD COME TO AN END BY FRI AFTN ALTHOUGH
THE COLD CONDITIONS WILLL CONT THRU THE WEEKEND. PLAN TO FCST BLW
GUIDANCE TEMPERATURES DUE TO THE SNOW CVR EXPECTED OVR MUCH OF THE
CWA.
GKS
&&
.AVIATION...
FOR THE 12Z TAFS...
ARCTIC AIR CONTINUED TO SLIDE INTO THE AREA FROM THE NORTHWEST EARLY
THIS MORNING. FREEZING RAIN CONTINED FROM CENTRAL INTO NORTHEAST MO
WITH RAIN ACROSS THE REMAINDER OF THE REGION. RADAR INDICATED THE
EDGE OF THE PRECIPITATION FROM JUST WEST OF COU TO NEAR UIN. TEMPS
ACROSS THE STL METRO AREA ARE EXPECTED TO SLOWLY DROP DURING THE
MORNING. EXPECT THE TEMP TO REACH THE FREEZING MARK AROUND 16Z WITH
THE FREEZING RAIN BECOMING MIXED WITH SLEET BY LATE AFTERNOON.
EXPECT A MIXTURE OF FREEZING RAIN AND SLEET IN COU AND UIN MUCH OF
THE DAY. BUFKIT SOUNDING FORECAST OFF THE NAM COOLS THE ATMOSPHERE
DOWN AFTER MIDNIGHT AT COU AND UIN TO CHANGE THE PRECIPITATION TO
SNOW.
TPS
&&
.LSX WATCHES/WARNINGS/ADVISORIES...
MO...WINTER STORM WARNING UNTIL 9 AM CST FRIDAY FOR CRAWFORD-FRANKLIN-
JEFFERSON-ST. CHARLES-ST. LOUIS-ST. LOUIS CITY-WASHINGTON.
WINTER WEATHER ADVISORY FROM NOON TODAY TO 9 AM CST FRIDAY FOR
IRON-MADISON-REYNOLDS-ST. FRANCOIS-STE. GENEVIEVE.
WINTER STORM WARNING UNTIL 9 AM CST FRIDAY FOR AUDRAIN-BOONE-
CALLAWAY-COLE-GASCONADE-KNOX-LEWIS-LINCOLN-MARION-MONITEAU-
MONROE-MONTGOMERY-OSAGE-PIKE-RALLS-SHELBY-WARREN.
IL...WINTER STORM WARNING UNTIL 9 AM CST FRIDAY FOR CALHOUN IL-GREENE
IL-JERSEY IL-MACOUPIN IL.
WINTER WEATHER ADVISORY FROM NOON TODAY TO 9 AM CST FRIDAY FOR
CLINTON IL-FAYETTE IL-MARION IL-RANDOLPH IL-WASHINGTON IL.
WINTER STORM WARNING UNTIL 9 AM CST FRIDAY FOR ADAMS IL-BROWN IL-
PIKE IL.
WINTER STORM WARNING FROM NOON TODAY TO 9 AM CST FRIDAY FOR BOND
IL-MADISON IL-MONROE IL-MONTGOMERY IL-ST. CLAIR IL.
&&
$$
WFO LSX
FXUS63 KLSX 301733
AFDLSX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE ST LOUIS MO
1133 AM CST THU NOV 30 2006
.DISCUSSION...
THE FIRST WINTER STORM OF THE SEASON WILL BE IMPACTING THE BI-
STATE REGION TODAT THROUGH FRIDAY MORNING. THE ARCTIC FRONT HAS
JUST PUSHED SOUTHEAST OF THE CWA ATTM WITH TEMPERATURES CONTINUING
TO FALL BEHIND IT CHANGING THE RAIN TO MAINLY FREEZING RAIN NORTH AND
WEST OF THE ST LOUIS METRO AREA. THE COLD AIR IS ADVANCING FASTER
SOUTHEASTWARD THAN THE MODELS HAD FCST. THE PRECIPITATION HAS
RECENTLY TAPERED OFF OVER THE NORTHWESTERN PORTION OF THE CWA WELL
BEHIND THE ARCTIC COLD FRONT. THE PRECIPITATION SHOULD PICK UP
AGAIN LATE THIS AFTERNOON INTO THE EVENING AS THE MID-UPR LVL LOW
CURRENTLY OVR SERN NM MOVES NORTHEAST THROUGH OK THIS AFTN AND
EVNG TO JUST S OF STL BY 12Z FRI. THE ASSOCIATED SFC LOW WILL MOVE
NEWD THRU AR THIS AFTN AND EVNG TO JUST E OF STL BY 12Z FRI. THE
HEAVIEST SNOW SHOULD OCCUR TGT OVR THE NRN AND WRN PTN OF THE CWA
LEFT OF THE TRACK OF THE MID LVL LOW AND ASSOCIATED 850 MB LOW. IT
APRS THAT THE DEFORMATION ZONE WILL SET UP OVR THE NRN PTN OF THE
CWA LT TGT INTO FRI MRNG WITH A TOTAL OF NR ONE FOOT OF SNOW
ACCUMULATION POSSIBLE. FURTHER S AND E INCLUDING THE STL METRO
AREA ICE ACCUMULATION WILL BE THE MAIN CONCERN TODAY AND THIS
EVENING AS THE STG SLY LLJ AHD OF THE 850 MB LOW BRINGS VRY STG
WAA AND ABUNDANT MOISTURE OVR THE COLD BLW FREEZING SFC LYR
RESULTING IN FREEZING RAIN AND SLEET ACCUMULATION. THE FCST
SOUNDINGS DEPICT THIS ELEVATED WRM LYR OVR THE SUBFREEZING SFC LYR
WHICH SHOULD RESULT IN ICE ACCUMULATION INITIALLY ON ELEVATED
SFCS...TREES AND POWER LINES THEN EVENTUALLY ON THE GROUND AND
ROAD SFC AS THE SFC AND GROUND TEMPERATURE CONTS TO LWR. STG WNDS
TDA AND TGT WILL ONLY AGGREVATE THE SITUATION LEADING TO BLOWING
AND DRIFTING SNOW TGT INTO FRI ESPECIALLY N AND W OF STL...AND
ALSO POSSIBLY LEADING TO DOWNED TREES AND POWER LINES DUE TO THE
COMBINATION OF THE WEIGHT OF THE ICE ACCUMULATION AND THE STRONG
WIND GUSTS. THE SNOW SHOULD COME TO AN END BY FRI AFTN ALTHOUGH
THE COLD CONDITIONS WILLL CONT THRU THE WEEKEND. PLAN TO FCST BLW
GUIDANCE TEMPERATURES DUE TO THE SNOW CVR EXPECTED OVR MUCH OF THE
CWA.
GKS
&&
.AVIATION...
FOR THE 18Z TAFS...
NOT TOO MUCH CHANGE IN THINKING FROM PREVIOUS ISSUANCE OF TAFS.
THERE HAS BEEN A SOLID BAND OF PRECIPITATION THIS MORNING
EXTENDING FROM CNTRL IL...THROUGH E CNTRL MO SWWD INTO S CNTRL MO.
KSTL/KSUS HAS SEEN STEADY -FZRAPL FROM THIS BAND ALL MORNING...
COMPARED TO KUIN/KCOU WHERE IT HAS BEEN MAINLY PRECIP FREE. WITH
NO REAL CHANGE IN THE M0VEMENT OF THE BAND...HAVE PREDOMINANT
-FZRAPL WITH MVRF/TEMPO IFR CONDITIONS GOING HERE THROUGH THE
EVENING. AT KCOU/KUIN...THINK THERE WILL ONLY BE SOME PATCHY
-FRDZSN (FLURRIES) THROUGH MID AFTN BEFORE MEASUREABLE FZRAPL
RETURNS BY LATE AFTN.
MAIN STORM SYSTEM WILL LIFT OUT OF THE SOUTHERN PLAINS THIS
EVENING...DRAMATICALLY INCREASING FORCING AND RESULTING
PRECIPITATION OVER THE AREA. HAVE FZRA CHANGING OVER TO PLSN FOR A
SHORT TIME THIS EVENING AT KCOU/KUIN BEFORE CHANGING OVER TO MDT
TO HVY SNOW WITH VLIFR CIGS/VBYS FOR 6+ HOURS LATE THIS EVENING/
OVERNIGHT. FEELING CONTINUES TO BE THAT CNTRL AND NERN MO/W CNTRL
IL WILL SEE SIGNIFICANT ACCUMULATIONS OF SNOW TONIGHT WITH SOME
AREAS EXCEEDING 1 FOOT. FARTHER TO THE SE...THERE WILL CONTINUE TO
BE ENOUGH WARM AIR ALOFT TO KEEP PRECIPITATION MAINLY FZRAPL WELL
INTO THE EVENING...WITH A CHANGE OVER LATER TONIGHT. KSTL/KSUS
WILL SIT ALONG SHARP LINE BETWEEN THE HEAVIEST SNOW BAND AND
RELATIVELY LIGHT AMOUNTS OF SNOW/BUT MORE ICE ACCUMULATION.
SYSTEM MOVES OUT QUICKLY TOMORROW MORNING...SO HAVE SHOWN A RAPID
IMPROVEMENT IN THE TAFS.
BRITT
&&
.LSX WATCHES/WARNINGS/ADVISORIES...
MO...WINTER STORM WARNING UNTIL 9 AM CST FRIDAY FOR AUDRAIN-BOONE-
CALLAWAY-COLE-CRAWFORD-FRANKLIN-GASCONADE-JEFFERSON-KNOX-
LEWIS-LINCOLN-MARION-MONITEAU-MONROE-MONTGOMERY-OSAGE-PIKE-
RALLS-SHELBY-ST. CHARLES-ST. LOUIS-ST. LOUIS CITY-WARREN-
WASHINGTON.
WINTER WEATHER ADVISORY UNTIL 9 AM CST FRIDAY FOR IRON-MADISON-
REYNOLDS-ST. FRANCOIS-STE. GENEVIEVE.
IL...WINTER STORM WARNING UNTIL 9 AM CST FRIDAY FOR ADAMS IL-BROWN IL-
CALHOUN IL-GREENE IL-JERSEY IL-MACOUPIN IL-PIKE IL.
WINTER WEATHER ADVISORY UNTIL 9 AM CST FRIDAY FOR CLINTON IL-
FAYETTE IL-MARION IL-RANDOLPH IL-WASHINGTON IL.
WINTER STORM WARNING UNTIL 9 AM CST FRIDAY FOR BOND IL-MADISON
IL-MONROE IL-MONTGOMERY IL-ST. CLAIR IL.
&&
$$
WFO LSX
FXUS63 KLSX 301841
AFDLSX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE ST LOUIS MO
1241 PM CST THU NOV 30 2006
.UPDATE...
FIRST THRUST OF THE WINTER STORM HAS BEEN IMPACTING THE REGION
THIS MORNING WITH PRIMARILY FREEZING RAIN AND SLEET. THE COMBO
HAS RESULTED IN ICE ACCUMLATIONS OF AROUND ONE HALF INCH ALONG A
LINE FROM OWENSVILLE TO TROY TO CARROLLTON. THE FREEZING LINE AT
MIDDAY RUNS FROM NORTHERN REYNOLDS COUNTY THROUGH ST CLAIR COUNTY
TO NORTHERN FAYETTE COUNTY. SUB-FREEZING AIR CONTINUES TO SPREAD
SOUTHWARD AND SHOULD OVERSPREAD THE REMAINDER OF SE MO AND SW IL
BY LATE AFTERNOON OR VERY EARLY EVENING.
THE AWAITED DEFORMATION ZONE HAS RAPIDLY DEVELOPED FROM OK INTO
ERN KS OVER THE LAST FEW HRS AS THE UPR SYSTEM MOVES INTO THE SRN
PLAINS. MEAINWHILE AXIS OF PRECIPITATION FROM SOUTHERN MISSOURI
THROUGH STL INTO CENTRAL ILLINOIS WILL HOLD STEADY. EXPECTING THE
VOID IN PCPN CURRENTLY ACRS CNTRL AND WRN MO WILL FILL-IN AS THE
AFTERNOON PROGRESSES IN ASSOCN WITH LARGE SCALE ASCENT IN ADVANCE
OF THE MID/UPR SYS.
PTYPE QUESTIONS STILL LURK. FREEZING RAIN AND SLEET SHOULD BE
PREDOMINATE THROUGH EARLY EVENING. WE ARE FAVORING THE COLDER RUC
AND GFS...EXPECTING A CHANGEOVER TO SNOW ACROSS CENTRAL AND NE
MO/WC IL DURING THE EVENING...AND WELL AFTER MIDNIGHT IN FAR
ECNTRL MO/STL AREA. POTENTIAL IS HIGH FOR HEAVY BANDED SNOWFALL
WITH RATES OF 2-3 IN/HR FROM CENTRAL MO INTO WCNTRL IL. CURRENT
THINKING IS A BAND OF 12+ INCHES FROM NORTHERN BOONE COUNTY TO
NEAR OR JUST SOUTH OF UIN. THE GFS SHOWS POSITIVE CAPE...SO AMOUNTS
OF 18+ ARE CERTAINLY NOT OUT OF THE QUESTION GIVEN POTENTIAL FOR
BANDING AND THUNDER ALONG THE AFOREMENTIONED AXIS. THERE WILL BE A
SHARP SEWD GRADIENT TO THE SNOW WITH AS MUCH AS 6-7 INCHES
POSSIBLE IN FAR NW SECTIONS OF THE STL METRO TAPERING TO AN INCH
OR SO IN FAR SE SXNS. OF MORE CONCERN ALONG THE I-44 CORRIDOR IS
THE POTENTIAL FOR HEAVY SLEET AND ICE/FREEZING RAIN ACCUMULATIONS...WITH
AN ADDITIONAL ONE INCH OF ICE MUCK QUITE LIKELY. THIS ZONE IS
LIKELY TO SEE ANOTHER 12-15H OF SLEET AND FREEZING RAIN BEFORE
CHANGING TO ALL SNOW.
GLASS
&&
.DISCUSSION...
THE FIRST WINTER STORM OF THE SEASON WILL BE IMPACTING THE BI-
STATE REGION TODAT THROUGH FRIDAY MORNING. THE ARCTIC FRONT HAS
JUST PUSHED SOUTHEAST OF THE CWA ATTM WITH TEMPERATURES CONTINUING
TO FALL BEHIND IT CHANGING THE RAIN TO MAINLY FREEZING RAIN NORTH AND
WEST OF THE ST LOUIS METRO AREA. THE COLD AIR IS ADVANCING FASTER
SOUTHEASTWARD THAN THE MODELS HAD FCST. THE PRECIPITATION HAS
RECENTLY TAPERED OFF OVER THE NORTHWESTERN PORTION OF THE CWA WELL
BEHIND THE ARCTIC COLD FRONT. THE PRECIPITATION SHOULD PICK UP
AGAIN LATE THIS AFTERNOON INTO THE EVENING AS THE MID-UPR LVL LOW
CURRENTLY OVR SERN NM MOVES NORTHEAST THROUGH OK THIS AFTN AND
EVNG TO JUST S OF STL BY 12Z FRI. THE ASSOCIATED SFC LOW WILL MOVE
NEWD THRU AR THIS AFTN AND EVNG TO JUST E OF STL BY 12Z FRI. THE
HEAVIEST SNOW SHOULD OCCUR TGT OVR THE NRN AND WRN PTN OF THE CWA
LEFT OF THE TRACK OF THE MID LVL LOW AND ASSOCIATED 850 MB LOW. IT
APRS THAT THE DEFORMATION ZONE WILL SET UP OVR THE NRN PTN OF THE
CWA LT TGT INTO FRI MRNG WITH A TOTAL OF NR ONE FOOT OF SNOW
ACCUMULATION POSSIBLE. FURTHER S AND E INCLUDING THE STL METRO
AREA ICE ACCUMULATION WILL BE THE MAIN CONCERN TODAY AND THIS
EVENING AS THE STG SLY LLJ AHD OF THE 850 MB LOW BRINGS VRY STG
WAA AND ABUNDANT MOISTURE OVR THE COLD BLW FREEZING SFC LYR
RESULTING IN FREEZING RAIN AND SLEET ACCUMULATION. THE FCST
SOUNDINGS DEPICT THIS ELEVATED WRM LYR OVR THE SUBFREEZING SFC LYR
WHICH SHOULD RESULT IN ICE ACCUMULATION INITIALLY ON ELEVATED
SFCS...TREES AND POWER LINES THEN EVENTUALLY ON THE GROUND AND
ROAD SFC AS THE SFC AND GROUND TEMPERATURE CONTS TO LWR. STG WNDS
TDA AND TGT WILL ONLY AGGREVATE THE SITUATION LEADING TO BLOWING
AND DRIFTING SNOW TGT INTO FRI ESPECIALLY N AND W OF STL...AND
ALSO POSSIBLY LEADING TO DOWNED TREES AND POWER LINES DUE TO THE
COMBINATION OF THE WEIGHT OF THE ICE ACCUMULATION AND THE STRONG
WIND GUSTS. THE SNOW SHOULD COME TO AN END BY FRI AFTN ALTHOUGH
THE COLD CONDITIONS WILLL CONT THRU THE WEEKEND. PLAN TO FCST BLW
GUIDANCE TEMPERATURES DUE TO THE SNOW CVR EXPECTED OVR MUCH OF THE
CWA.
GKS
&&
.AVIATION...
FOR THE 18Z TAFS...
NOT TOO MUCH CHANGE IN THINKING FROM PREVIOUS ISSUANCE OF TAFS.
THERE HAS BEEN A SOLID BAND OF PRECIPITATION THIS MORNING
EXTENDING FROM CNTRL IL...THROUGH E CNTRL MO SWWD INTO S CNTRL MO.
KSTL/KSUS HAS SEEN STEADY -FZRAPL FROM THIS BAND ALL MORNING...
COMPARED TO KUIN/KCOU WHERE IT HAS BEEN MAINLY PRECIP FREE. WITH
NO REAL CHANGE IN THE M0VEMENT OF THE BAND...HAVE PREDOMINANT
-FZRAPL WITH MVRF/TEMPO IFR CONDITIONS GOING HERE THROUGH THE
EVENING. AT KCOU/KUIN...THINK THERE WILL ONLY BE SOME PATCHY
-FRDZSN (FLURRIES) THROUGH MID AFTN BEFORE MEASUREABLE FZRAPL
RETURNS BY LATE AFTN.
MAIN STORM SYSTEM WILL LIFT OUT OF THE SOUTHERN PLAINS THIS
EVENING...DRAMATICALLY INCREASING FORCING AND RESULTING
PRECIPITATION OVER THE AREA. HAVE FZRA CHANGING OVER TO PLSN FOR A
SHORT TIME THIS EVENING AT KCOU/KUIN BEFORE CHANGING OVER TO MDT
TO HVY SNOW WITH VLIFR CIGS/VBYS FOR 6+ HOURS LATE THIS EVENING/
OVERNIGHT. FEELING CONTINUES TO BE THAT CNTRL AND NERN MO/W CNTRL
IL WILL SEE SIGNIFICANT ACCUMULATIONS OF SNOW TONIGHT WITH SOME
AREAS EXCEEDING 1 FOOT. FARTHER TO THE SE...THERE WILL CONTINUE TO
BE ENOUGH WARM AIR ALOFT TO KEEP PRECIPITATION MAINLY FZRAPL WELL
INTO THE EVENING...WITH A CHANGE OVER LATER TONIGHT. KSTL/KSUS
WILL SIT ALONG SHARP LINE BETWEEN THE HEAVIEST SNOW BAND AND
RELATIVELY LIGHT AMOUNTS OF SNOW/BUT MORE ICE ACCUMULATION.
SYSTEM MOVES OUT QUICKLY TOMORROW MORNING...SO HAVE SHOWN A RAPID
IMPROVEMENT IN THE TAFS.
BRITT
&&
.LSX WATCHES/WARNINGS/ADVISORIES...
MO...WINTER STORM WARNING UNTIL 9 AM CST FRIDAY FOR AUDRAIN-BOONE-
CALLAWAY-COLE-CRAWFORD-FRANKLIN-GASCONADE-JEFFERSON-KNOX-
LEWIS-LINCOLN-MARION-MONITEAU-MONROE-MONTGOMERY-OSAGE-PIKE-
RALLS-SHELBY-ST. CHARLES-ST. LOUIS-ST. LOUIS CITY-WARREN-
WASHINGTON.
WINTER WEATHER ADVISORY UNTIL 9 AM CST FRIDAY FOR IRON-MADISON-
REYNOLDS-ST. FRANCOIS-STE. GENEVIEVE.
IL...WINTER STORM WARNING UNTIL 9 AM CST FRIDAY FOR ADAMS IL-BOND IL-
BROWN IL-CALHOUN IL-GREENE IL-JERSEY IL-MACOUPIN IL-MADISON
IL-MONROE IL-MONTGOMERY IL-PIKE IL-ST. CLAIR IL.
WINTER WEATHER ADVISORY UNTIL 9 AM CST FRIDAY FOR CLINTON IL-
FAYETTE IL-MARION IL-RANDOLPH IL-WASHINGTON IL.
&&
$$
WFO LSX
FXUS63 KLSX 302136
AFDLSX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE ST LOUIS MO
336 PM CST THU NOV 30 2006
.DISCUSSION...
...CONDITIONS EXPECTED TO CONTINUE TO DETERIORATE THIS EVENING...
...WINTER WEATHER ADVISORY AREA BEING UPGRADED TO WARNING...
MAIN UNCERTAINTY DEALS WITH THIS PACKAGE DEALS WITH HOW MUCH SNOW
ACCUMULATION VS. SLEET/GLAZE (ICE FROM FREEZING RAIN (FZRA))
ACCUMULATION THERE WILL BE OVER THE CNTRL PART OF THE CWA. WILL
CONTINUE TO FAVOR THE COOLER SOUNDINGS OF THE RUC/GFS AS
PRECPITATION TYPE ALL DAY HAVE BEEN MORE SLEET THAN THE ALL FZRA
SOUNDINGS THE NAM HAS BEEN FORECASTING.
THERE IS A BAND OF MDT TO HVY PRECIPITATION EXTENDING FROM E CNTRL
AND CNTRL MO SWWD THROUGH THE 0ZARKS INTO WRN AR ATTM. THIS BAND
WILL CONTINUE TO SPREAD NEWD THIS EVENING INTO CNTRL IL. THIS
MEANS THAT THE SAME AREA WILL SEE AN EXTENDED PERIOD OF MDT-HVY
SLEET WITH SOME FREEZING RAIN AND SNOW WELL INTO THE EVENING...
RESULTING IN SIGNIFICANT ACCUMULATION OF SLEET/GLAZE. CHANGEOVER TO
ALL SNOW WILL PROBABLY TAKE A WHILE AS GFS SOUNDINGS HAVE A
RELATIVELY WARM LAYER THROUGH LATE EVENING. THINK THERE WILL BE A
SHARP TRADE OFF BETWEEN JUST SNOW VS. A MIX OF SNOW/SLEET/FZRA ON
THE ERN EDGE OF THE DEFORMATION ZONE. THINKING IS THAT SLEET/GLAZE
TOTALS WILL TAKE AWAY FROM THE JUST SNOW TOTALS OVR ERN STL METRO
AREA WITH ONLY 2-4 INCHES...WHEREAS THE WRN METRO COUNTIES WILL
SEE QUITE A BIT OF SLEET WITH 6+ INCHES OF SNOW ON TOP OF IT.
FARTHER NW OVER CNTRL AND NERN MO/W CNTRL IL...THIS MIX WILL
SWITCH OVER BY MID EVENING AS THE DEFORMATION ZONE NOW OVER WRN
MO/ERN KS/OK LIFTS NEWD WITH THE MAIN STORM SYSTEM. SOUNDINGS WILL
QUICKLY CHANGE TO ALL SNOW. ALL OF THE NECESSARY SYNOPTIC AND
MESOSCALE FORCING WILL SET UP TO PRODUCE A BAND OF VERY HEAVY
SNOWFALL OVER THIS AREA...WITH 10-14 INCH AMOUNTS EXPECTED BY THE
TIME THE SYSTEM LIFTS OUT TOMORROW MORNING.
HAVE UPGRADED THE ADVISORY TO A WARNING OVER THE FAR SRN AND ERN
COUNTIES AS THE TEMPERATURE WILL CONTINUE TO DROP. ONCE THE
PRECIPITATION CHANGED OVER...SHOULD SEE FZRA/SLEET TONIGHT INTO
EARLY TOMORROW...WITH SOME MINOR SNOW ACCUMULATIONS ON TOP OF IT
AS THE DEFORMATION ZONE LIFTS NEWD.
OTHERWISE...WENT COLDER ON GUIDANCE TEMPS AS THEY ARE NOT TAKING
INTO ACCOUNT THE FRESH SNOW COVER. REST OF FORECAST IS DRY WITH A
GRADUAL MODERATING OF TEMPERATURES AS NO SIGNIFICANT SYSTEMS ARE
EXPECTED TO AFFECT THE AREA UNTIL LATE NEXT WEEK.
BRITT/BYRD/GLASS
&&
.AVIATION...
FOR THE 18Z TAFS...
NOT TOO MUCH CHANGE IN THINKING FROM PREVIOUS ISSUANCE OF TAFS.
THERE HAS BEEN A SOLID BAND OF PRECIPITATION THIS MORNING
EXTENDING FROM CNTRL IL...THROUGH E CNTRL MO SWWD INTO S CNTRL MO.
KSTL/KSUS HAS SEEN STEADY -FZRAPL FROM THIS BAND ALL MORNING...
COMPARED TO KUIN/KCOU WHERE IT HAS BEEN MAINLY PRECIP FREE. WITH
NO REAL CHANGE IN THE M0VEMENT OF THE BAND...HAVE PREDOMINANT
-FZRAPL WITH MVRF/TEMPO IFR CONDITIONS GOING HERE THROUGH THE
EVENING. AT KCOU/KUIN...THINK THERE WILL ONLY BE SOME PATCHY
-FRDZSN (FLURRIES) THROUGH MID AFTN BEFORE MEASUREABLE FZRAPL
RETURNS BY LATE AFTN.
MAIN STORM SYSTEM WILL LIFT OUT OF THE SOUTHERN PLAINS THIS
EVENING...DRAMATICALLY INCREASING FORCING AND RESULTING
PRECIPITATION OVER THE AREA. HAVE FZRA CHANGING OVER TO PLSN FOR A
SHORT TIME THIS EVENING AT KCOU/KUIN BEFORE CHANGING OVER TO MDT
TO HVY SNOW WITH VLIFR CIGS/VBYS FOR 6+ HOURS LATE THIS EVENING/
OVERNIGHT. FEELING CONTINUES TO BE THAT CNTRL AND NERN MO/W CNTRL
IL WILL SEE SIGNIFICANT ACCUMULATIONS OF SNOW TONIGHT WITH SOME
AREAS EXCEEDING 1 FOOT. FARTHER TO THE SE...THERE WILL CONTINUE TO
BE ENOUGH WARM AIR ALOFT TO KEEP PRECIPITATION MAINLY FZRAPL WELL
INTO THE EVENING...WITH A CHANGE OVER LATER TONIGHT. KSTL/KSUS
WILL SIT ALONG SHARP LINE BETWEEN THE HEAVIEST SNOW BAND AND
RELATIVELY LIGHT AMOUNTS OF SNOW/BUT MORE ICE ACCUMULATION.
SYSTEM MOVES OUT QUICKLY TOMORROW MORNING...SO HAVE SHOWN A RAPID
IMPROVEMENT IN THE TAFS.
BRITT
&&
.LSX WATCHES/WARNINGS/ADVISORIES...
MO...WINTER STORM WARNING UNTIL 9 AM CST FRIDAY FOR AUDRAIN-BOONE-
CALLAWAY-COLE-CRAWFORD-FRANKLIN-GASCONADE-JEFFERSON-KNOX-
LEWIS-LINCOLN-MARION-MONITEAU-MONROE-MONTGOMERY-OSAGE-PIKE-
RALLS-SHELBY-ST. CHARLES-ST. LOUIS-ST. LOUIS CITY-WARREN-
WASHINGTON.
WINTER WEATHER ADVISORY UNTIL 9 AM CST FRIDAY FOR IRON-MADISON-
REYNOLDS-ST. FRANCOIS-STE. GENEVIEVE.
IL...WINTER STORM WARNING UNTIL 9 AM CST FRIDAY FOR ADAMS IL-BOND IL-
BROWN IL-CALHOUN IL-GREENE IL-JERSEY IL-MACOUPIN IL-MADISON
IL-MONROE IL-MONTGOMERY IL-PIKE IL-ST. CLAIR IL.
WINTER WEATHER ADVISORY UNTIL 9 AM CST FRIDAY FOR CLINTON IL-
FAYETTE IL-MARION IL-RANDOLPH IL-WASHINGTON IL.
&&
$$
WFO LSX
FXUS63 KLSX 302324
AFDLSX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE ST LOUIS MO
524 PM CST THU NOV 30 2006
.DISCUSSION...
...CONDITIONS EXPECTED TO CONTINUE TO DETERIORATE THIS EVENING...
...WINTER WEATHER ADVISORY AREA BEING UPGRADED TO WARNING...
MAIN UNCERTAINTY DEALS WITH THIS PACKAGE DEALS WITH HOW MUCH SNOW
ACCUMULATION VS. SLEET/GLAZE (ICE FROM FREEZING RAIN (FZRA))
ACCUMULATION THERE WILL BE OVER THE CNTRL PART OF THE CWA. WILL
CONTINUE TO FAVOR THE COOLER SOUNDINGS OF THE RUC/GFS AS
PRECPITATION TYPE ALL DAY HAVE BEEN MORE SLEET THAN THE ALL FZRA
SOUNDINGS THE NAM HAS BEEN FORECASTING.
THERE IS A BAND OF MDT TO HVY PRECIPITATION EXTENDING FROM E CNTRL
AND CNTRL MO SWWD THROUGH THE 0ZARKS INTO WRN AR ATTM. THIS BAND
WILL CONTINUE TO SPREAD NEWD THIS EVENING INTO CNTRL IL. THIS
MEANS THAT THE SAME AREA WILL SEE AN EXTENDED PERIOD OF MDT-HVY
SLEET WITH SOME FREEZING RAIN AND SNOW WELL INTO THE EVENING...
RESULTING IN SIGNIFICANT ACCUMULATION OF SLEET/GLAZE. CHANGEOVER TO
ALL SNOW WILL PROBABLY TAKE A WHILE AS GFS SOUNDINGS HAVE A
RELATIVELY WARM LAYER THROUGH LATE EVENING. THINK THERE WILL BE A
SHARP TRADE OFF BETWEEN JUST SNOW VS. A MIX OF SNOW/SLEET/FZRA ON
THE ERN EDGE OF THE DEFORMATION ZONE. THINKING IS THAT SLEET/GLAZE
TOTALS WILL TAKE AWAY FROM THE JUST SNOW TOTALS OVR ERN STL METRO
AREA WITH ONLY 2-4 INCHES...WHEREAS THE WRN METRO COUNTIES WILL
SEE QUITE A BIT OF SLEET WITH 6+ INCHES OF SNOW ON TOP OF IT.
FARTHER NW OVER CNTRL AND NERN MO/W CNTRL IL...THIS MIX WILL
SWITCH OVER BY MID EVENING AS THE DEFORMATION ZONE NOW OVER WRN
MO/ERN KS/OK LIFTS NEWD WITH THE MAIN STORM SYSTEM. SOUNDINGS WILL
QUICKLY CHANGE TO ALL SNOW. ALL OF THE NECESSARY SYNOPTIC AND
MESOSCALE FORCING WILL SET UP TO PRODUCE A BAND OF VERY HEAVY
SNOWFALL OVER THIS AREA...WITH 10-14 INCH AMOUNTS EXPECTED BY THE
TIME THE SYSTEM LIFTS OUT TOMORROW MORNING.
HAVE UPGRADED THE ADVISORY TO A WARNING OVER THE FAR SRN AND ERN
COUNTIES AS THE TEMPERATURE WILL CONTINUE TO DROP. ONCE THE
PRECIPITATION CHANGED OVER...SHOULD SEE FZRA/SLEET TONIGHT INTO
EARLY TOMORROW...WITH SOME MINOR SNOW ACCUMULATIONS ON TOP OF IT
AS THE DEFORMATION ZONE LIFTS NEWD.
OTHERWISE...WENT COLDER ON GUIDANCE TEMPS AS THEY ARE NOT TAKING
INTO ACCOUNT THE FRESH SNOW COVER. REST OF FORECAST IS DRY WITH A
GRADUAL MODERATING OF TEMPERATURES AS NO SIGNIFICANT SYSTEMS ARE
EXPECTED TO AFFECT THE AREA UNTIL LATE NEXT WEEK.
BRITT/BYRD/GLASS
&&
.AVIATION...
FOR THE 00Z TAFS...
NOT TOO MUCH CHANGE IN THINKING FROM PREVIOUS ISSUANCE OF TAFS.
SOLID BAND OF PRECIPITATION EXTENDING FROM CNTRL IL...THROUGH E
CNTRL MO SWWD INTO S CNTRL MO. KSTL/KSUS HAS SEEN STEADY -FZRAPL
FROM THIS BAND ALL DAY AND NOW KCOU AND KUIN ARE STARTING TO GET
IN THE ACT AS MAIN DEFORMATION ZONE SETS UP ACROSS CWA.
PLSN AT KCOU/KUIN WILL CHANGE OVER TO MDT TO HVY SNOW WITH VLIFR
CIGS/VBYS FOR 6+ HOURS LATE THIS EVENING/OVERNIGHT. THERE WILL
CONTINUE TO BE ENOUGH WARM AIR ALOFT TO KEEP PRECIPITATION MAINLY
PL WELL INTO THE EVENING...WITH A CHANGE OVER LATER TONIGHT AT
KSUS AND KSTL. KSTL/KSUS WILL SIT ALONG SHARP LINE BETWEEN THE
HEAVIEST SNOW BAND AND RELATIVELY LIGHT AMOUNTS OF SNOW/BUT VERY
SIGNIFICANT ICE ACCUMULATION.
SYSTEM MOVES OUT QUICKLY TOMORROW MORNING...SO HAVE SHOWN A RAPID
IMPROVEMENT IN THE TAFS...WITH CLEARING IN THE AFTERNOON.
CVKING
&&
.LSX WATCHES/WARNINGS/ADVISORIES...
MO...WINTER STORM WARNING UNTIL 9 AM CST FRIDAY FOR AUDRAIN-BOONE-
CALLAWAY-COLE-CRAWFORD-FRANKLIN-GASCONADE-IRON-JEFFERSON-
KNOX-LEWIS-LINCOLN-MADISON-MARION-MONITEAU-MONROE-
MONTGOMERY-OSAGE-PIKE-RALLS-REYNOLDS-SHELBY-ST. CHARLES-ST.
FRANCOIS-ST. LOUIS-ST. LOUIS CITY-STE. GENEVIEVE-WARREN-
WASHINGTON.
IL...WINTER STORM WARNING UNTIL 9 AM CST FRIDAY FOR ADAMS IL-BOND IL-
BROWN IL-CALHOUN IL-CLINTON IL-FAYETTE IL-GREENE IL-JERSEY
IL-MACOUPIN IL-MADISON IL-MARION IL-MONROE IL-MONTGOMERY IL-
PIKE IL-RANDOLPH IL-ST. CLAIR IL-WASHINGTON IL.
&&
$$
WFO LSX
FXUS63 KLSX 010547
AFDLSX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE ST LOUIS MO
1147 PM CST THU NOV 30 2006
.DISCUSSION...
...CONDITIONS EXPECTED TO CONTINUE TO DETERIORATE THIS EVENING...
...WINTER WEATHER ADVISORY AREA BEING UPGRADED TO WARNING...
MAIN UNCERTAINTY DEALS WITH THIS PACKAGE DEALS WITH HOW MUCH SNOW
ACCUMULATION VS. SLEET/GLAZE (ICE FROM FREEZING RAIN (FZRA))
ACCUMULATION THERE WILL BE OVER THE CNTRL PART OF THE CWA. WILL
CONTINUE TO FAVOR THE COOLER SOUNDINGS OF THE RUC/GFS AS
PRECPITATION TYPE ALL DAY HAVE BEEN MORE SLEET THAN THE ALL FZRA
SOUNDINGS THE NAM HAS BEEN FORECASTING.
THERE IS A BAND OF MDT TO HVY PRECIPITATION EXTENDING FROM E CNTRL
AND CNTRL MO SWWD THROUGH THE 0ZARKS INTO WRN AR ATTM. THIS BAND
WILL CONTINUE TO SPREAD NEWD THIS EVENING INTO CNTRL IL. THIS
MEANS THAT THE SAME AREA WILL SEE AN EXTENDED PERIOD OF MDT-HVY
SLEET WITH SOME FREEZING RAIN AND SNOW WELL INTO THE EVENING...
RESULTING IN SIGNIFICANT ACCUMULATION OF SLEET/GLAZE. CHANGEOVER TO
ALL SNOW WILL PROBABLY TAKE A WHILE AS GFS SOUNDINGS HAVE A
RELATIVELY WARM LAYER THROUGH LATE EVENING. THINK THERE WILL BE A
SHARP TRADE OFF BETWEEN JUST SNOW VS. A MIX OF SNOW/SLEET/FZRA ON
THE ERN EDGE OF THE DEFORMATION ZONE. THINKING IS THAT SLEET/GLAZE
TOTALS WILL TAKE AWAY FROM THE JUST SNOW TOTALS OVR ERN STL METRO
AREA WITH ONLY 2-4 INCHES...WHEREAS THE WRN METRO COUNTIES WILL
SEE QUITE A BIT OF SLEET WITH 6+ INCHES OF SNOW ON TOP OF IT.
FARTHER NW OVER CNTRL AND NERN MO/W CNTRL IL...THIS MIX WILL
SWITCH OVER BY MID EVENING AS THE DEFORMATION ZONE NOW OVER WRN
MO/ERN KS/OK LIFTS NEWD WITH THE MAIN STORM SYSTEM. SOUNDINGS WILL
QUICKLY CHANGE TO ALL SNOW. ALL OF THE NECESSARY SYNOPTIC AND
MESOSCALE FORCING WILL SET UP TO PRODUCE A BAND OF VERY HEAVY
SNOWFALL OVER THIS AREA...WITH 10-14 INCH AMOUNTS EXPECTED BY THE
TIME THE SYSTEM LIFTS OUT TOMORROW MORNING.
HAVE UPGRADED THE ADVISORY TO A WARNING OVER THE FAR SRN AND ERN
COUNTIES AS THE TEMPERATURE WILL CONTINUE TO DROP. ONCE THE
PRECIPITATION CHANGED OVER...SHOULD SEE FZRA/SLEET TONIGHT INTO
EARLY TOMORROW...WITH SOME MINOR SNOW ACCUMULATIONS ON TOP OF IT
AS THE DEFORMATION ZONE LIFTS NEWD.
OTHERWISE...WENT COLDER ON GUIDANCE TEMPS AS THEY ARE NOT TAKING
INTO ACCOUNT THE FRESH SNOW COVER. REST OF FORECAST IS DRY WITH A
GRADUAL MODERATING OF TEMPERATURES AS NO SIGNIFICANT SYSTEMS ARE
EXPECTED TO AFFECT THE AREA UNTIL LATE NEXT WEEK.
BRITT/BYRD/GLASS
&&
.AVIATION...
FOR THE 06Z TAFS...
THE LONG AND THE SHORT OF IT IS THAT THE WEATHER IS BAD...AND WILL
STAY BAD FOR AT LEAST THE NEXT 8 TO 10 HOURS ACROSS THE CWFA. IFR
AND LIFR CIGS AND VSBYS CAN BE EXPECTED IN MODERATE TO HEAVY SNOW.
WHERE THE FLIGHT CATEGORY IMPROVES TO MARGINAL LEVELS...ICING FROM SLEET
AND FREEZING RAIN WILL BE AN ISSUE. SLEET AND FREEZING RAIN SHOULD
TURN OVER TO ALL SNOW FROM CENTRAL MISSOURI EASTWARD BETWEEN NOW
AND 09Z TO 10Z FRIDAY MORNING ACROSS THE WHOLE AREA. THE STORM
SHOULD FINALLY PULL OUT AND END FROM WEST TO EAST BETWEEN 12Z AND
16Z FRIDAY MORNING...LEAVING BEHIND MARGINAL CIGS...AND PROBABLY A
LITTLE FOG TOO. LOOKS LIKE LOW CLOUDS WILL PULL AWAY DURING THE
EARLY AFTERNOON SOMETIME. WINDS WILL BECOME WEST-NORTHWESTERLY AS
THE SURFACE LOW MOVES INTO ILLINOIS AND SHOULD REMAIN STRONG...IN
THE 12KT TO 20KT RANGE THROUGH THE AFTERNOON.
CARNEY
&&
.LSX WATCHES/WARNINGS/ADVISORIES...
MO...WINTER STORM WARNING UNTIL 9 AM CST FRIDAY FOR AUDRAIN-BOONE-
CALLAWAY-COLE-CRAWFORD-FRANKLIN-GASCONADE-IRON-JEFFERSON-
KNOX-LEWIS-LINCOLN-MADISON-MARION-MONITEAU-MONROE-
MONTGOMERY-OSAGE-PIKE-RALLS-REYNOLDS-SHELBY-ST.
CHARLES-ST.
FRANCOIS-ST. LOUIS-ST. LOUIS CITY-STE.
GENEVIEVE-WARREN-
WASHINGTON.
IL...WINTER STORM WARNING UNTIL 9 AM CST FRIDAY FOR ADAMS IL-BOND IL-
BROWN IL-CALHOUN IL-CLINTON IL-FAYETTE IL-GREENE
IL-JERSEY
IL-MACOUPIN IL-MADISON IL-MARION IL-MONROE
IL-MONTGOMERY IL-
PIKE IL-RANDOLPH IL-ST. CLAIR IL-WASHINGTON IL.
&&
$$
WFO LSX
FXUS63 KLSX 011043
AFDLSX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE ST LOUIS MO
443 AM CST FRI DEC 1 2006
.DISCUSSION...
...WINTER STORM PARALYZING MUCH OF BI-STATE REGION THIS MORNING...
FIRST WINTER STORM OF THE 2006-07 SEASON IS CERTAINLY TURNING OUT TO
BE AN EXTREMLY POTENT SYSTEM. INTS UPR LVL LO SPINNING INTO S CNTRL
MO SET UP DEFORMATION ZN FROM JUST N OF KJLN...THRU KCOU...TO NR
KUIN OVRNGT. ENHACING THE HEAVY SNOWFALL THAT IS TYPICAL WITH THE
DEF ZN...SPOTTY CNVTN NR KCOU HAS BEEN PRODUCING SNOWFALL RATES OF
UP TO 3"/HR. KOMU TV REPORTS 11 INCHES OF SNOW ON THE
GROUND...WITH DRIFTS OF NEARLY 2 FEET. MODOT AS ALSO SUSPENDED
PLOWING OPERATIONS IN MID MO...AND PARTS OF I-70 ARE CLOSED.
FURTHER E...ROUGHLY ON AND EAST OF THE I-44/I-70 CORRIDOR...SVR
ICING IS THE MAJOR PROBLEM...WITH AN ICY MIX OF SLEET AND FREEZING
RAIN THAT BEGAN THU MRNG AND PERSISTED INTO LATE THU EVE. PCPN IN
THIS ZONE FINALLY BEGAN THE CHGOVER TO SNOW OVR THE LAST FEW HRS.
POWER OUTAGES ARE COMMON...AND POWER IS NOW OUT TO OVER 150,000
CUSTOMERS IN STL METRO AREA.
WITH UPR LO ON THE MOVE...THINK PCPN ACR CWA WL BE WINDING DOWN
FAIRLY QUICKLY IN THE 12Z-15Z TIME FRAME...ALTHO XTRMLY HVY SNOW
NOW FALLING OVR MID MO WL BE PUSHING INTO KUIN AREA BTWN NOW AND
12Z QUICKLY ADDING TO THE ACCUMULATIONS IN THIS AREA BY DAYBREAK.
STL METRO WL PROBABLY BE ON THE E EDGE OF THE HVIEST ACCUMULATIONS...BUT
THINK THE HEAVIEST SNOWFALL FOR THIS AREA IS STILL IN THE OFFING
OVR THE NXT CPL OF HRS. MSTR WRAPPING N OF LO IS CAUSING BANDS OF
LGT/MDT SNW TO REFORM S OF MAIN DEFZN...AND THINK AREA WL SEE SVRL
SHOTS OF MDT/HVY SNOW BTWN NOW AND 12Z...WITH THE PRIMARY IMPACT
OF THIS SNOW OCRG W AND N OF DOWNTOWN.
AS FAR AS TOTAL SNOWFALL IS CONCERNED...SM LOCATIONS ALG THE KCOU-
KUIN LN WL TOP 12-14 INCHES...WHILE FAR E COUNTIES WL LIKELY PICK
UP AN INCH OR SO.
HWVR...WITH WINDS PICKING UP WX PROBLEMS SHUD PERSIST PAST THE END OF
THE PCPN. IN THE HVY SNOWFALL AREAS...FROM CNTRL MO INTO W CNTRL
IL...BLOWING AND DRIFTING WL BE A PROBLEM...WHILE IN THE I-44/I-70
CORRIDOR AM XTRMLY CONCERNED THAT POWER OUTAGES WL BCM EVEN MORE
WIDESPREAD AS THE SFC LO PULLS E AND NW WINDS INCR. BECAUSE OF
THIS...WL EXTEND THE WINTER STORM WARNING FOR ENTR AREA UNTIL 18Z.
GENLY DRY AND COLD CONDS FCST FOR RMNDR OF SHORT TERM PD. FOLLOWED
LEAD OF ERYR FCSTS AND TRIMMED BACK TEMPS EVEN MORE IN DEEP SNOW
COVER...WITH SINGLE DIGITS MIN EXPECTED OVR SOME OF THE SNOW FIELD
THE NXT CPL NIGHTS.
TRUETT
&&
.AVIATION...
FOR THE 06Z TAFS...
THE LONG AND THE SHORT OF IT IS THAT THE WEATHER IS BAD...AND WILL
STAY BAD FOR AT LEAST THE NEXT 8 TO 10 HOURS ACROSS THE CWFA. IFR
AND LIFR CIGS AND VSBYS CAN BE EXPECTED IN MODERATE TO HEAVY SNOW.
WHERE THE FLIGHT CATEGORY IMPROVES TO MARGINAL LEVELS...ICING FROM SLEET
AND FREEZING RAIN WILL BE AN ISSUE. SLEET AND FREEZING RAIN SHOULD
TURN OVER TO ALL SNOW FROM CENTRAL MISSOURI EASTWARD BETWEEN NOW
AND 09Z TO 10Z FRIDAY MORNING ACROSS THE WHOLE AREA. THE STORM
SHOULD FINALLY PULL OUT AND END FROM WEST TO EAST BETWEEN 12Z AND
16Z FRIDAY MORNING...LEAVING BEHIND MARGINAL CIGS...AND PROBABLY A
LITTLE FOG TOO. LOOKS LIKE LOW CLOUDS WILL PULL AWAY DURING THE
EARLY AFTERNOON SOMETIME. WINDS WILL BECOME WEST-NORTHWESTERLY AS
THE SURFACE LOW MOVES INTO ILLINOIS AND SHOULD REMAIN STRONG...IN
THE 12KT TO 20KT RANGE THROUGH THE AFTERNOON.
CARNEY
&&
.LSX WATCHES/WARNINGS/ADVISORIES...
MO...WINTER STORM WARNING UNTIL NOON CST TODAY FOR AUDRAIN-BOONE-
CALLAWAY-COLE-CRAWFORD-FRANKLIN-GASCONADE-IRON-JEFFERSON-
KNOX-LEWIS-LINCOLN-MADISON-MARION-MONITEAU-MONROE-
MONTGOMERY-OSAGE-PIKE-RALLS-REYNOLDS-SHELBY-ST.
CHARLES-ST.
FRANCOIS-ST. LOUIS-ST. LOUIS CITY-STE.
GENEVIEVE-WARREN-
WASHINGTON.
IL...WINTER STORM WARNING UNTIL NOON CST TODAY FOR ADAMS IL-BOND IL-
BROWN IL-CALHOUN IL-CLINTON IL-FAYETTE IL-GREENE
IL-JERSEY
IL-MACOUPIN IL-MADISON IL-MARION IL-MONROE
IL-MONTGOMERY IL-
PIKE IL-RANDOLPH IL-ST. CLAIR IL-WASHINGTON IL.
&&
$$
WFO LSX
FXUS63 KLSX 011049
AFDLSX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE ST LOUIS MO
449 AM CST FRI DEC 1 2006
.DISCUSSION...
...WINTER STORM PARALYZING MUCH OF BI-STATE REGION THIS MORNING...
FIRST WINTER STORM OF THE 2006-07 SEASON IS CERTAINLY TURNING OUT TO
BE AN EXTREMLY POTENT SYSTEM. INTS UPR LVL LO SPINNING INTO S CNTRL
MO SET UP DEFORMATION ZN FROM JUST N OF KJLN...THRU KCOU...TO NR
KUIN OVRNGT. ENHACING THE HEAVY SNOWFALL THAT IS TYPICAL WITH THE
DEF ZN...SPOTTY CNVTN NR KCOU HAS BEEN PRODUCING SNOWFALL RATES OF
UP TO 3"/HR. KOMU TV REPORTS 11 INCHES OF SNOW ON THE
GROUND...WITH DRIFTS OF NEARLY 2 FEET. MODOT AS ALSO SUSPENDED
PLOWING OPERATIONS IN MID MO...AND PARTS OF I-70 ARE CLOSED.
FURTHER E...ROUGHLY ON AND EAST OF THE I-44/I-70 CORRIDOR...SVR
ICING IS THE MAJOR PROBLEM...WITH AN ICY MIX OF SLEET AND FREEZING
RAIN THAT BEGAN THU MRNG AND PERSISTED INTO LATE THU EVE. PCPN IN
THIS ZONE FINALLY BEGAN THE CHGOVER TO SNOW OVR THE LAST FEW HRS.
POWER OUTAGES ARE COMMON...AND POWER IS NOW OUT TO OVER 150,000
CUSTOMERS IN STL METRO AREA.
WITH UPR LO ON THE MOVE...THINK PCPN ACR CWA WL BE WINDING DOWN
FAIRLY QUICKLY IN THE 12Z-15Z TIME FRAME...ALTHO XTRMLY HVY SNOW
NOW FALLING OVR MID MO WL BE PUSHING INTO KUIN AREA BTWN NOW AND
12Z QUICKLY ADDING TO THE ACCUMULATIONS IN THIS AREA BY DAYBREAK.
STL METRO WL PROBABLY BE ON THE E EDGE OF THE HVIEST ACCUMULATIONS...BUT
THINK THE HEAVIEST SNOWFALL FOR THIS AREA IS STILL IN THE OFFING
OVR THE NXT CPL OF HRS. MSTR WRAPPING N OF LO IS CAUSING BANDS OF
LGT/MDT SNW TO REFORM S OF MAIN DEFZN...AND THINK AREA WL SEE SVRL
SHOTS OF MDT/HVY SNOW BTWN NOW AND 12Z...WITH THE PRIMARY IMPACT
OF THIS SNOW OCRG W AND N OF DOWNTOWN.
AS FAR AS TOTAL SNOWFALL IS CONCERNED...SM LOCATIONS ALG THE KCOU-
KUIN LN WL TOP 12-14 INCHES...WHILE FAR E COUNTIES WL LIKELY PICK
UP AN INCH OR SO.
HWVR...WITH WINDS PICKING UP WX PROBLEMS SHUD PERSIST PAST THE END OF
THE PCPN. IN THE HVY SNOWFALL AREAS...FROM CNTRL MO INTO W CNTRL
IL...BLOWING AND DRIFTING WL BE A PROBLEM...WHILE IN THE I-44/I-70
CORRIDOR AM XTRMLY CONCERNED THAT POWER OUTAGES WL BCM EVEN MORE
WIDESPREAD AS THE SFC LO PULLS E AND NW WINDS INCR. BECAUSE OF
THIS...WL EXTEND THE WINTER STORM WARNING FOR ENTR AREA UNTIL 18Z.
GENLY DRY AND COLD CONDS FCST FOR RMNDR OF SHORT TERM PD. FOLLOWED
LEAD OF ERYR FCSTS AND TRIMMED BACK TEMPS EVEN MORE IN DEEP SNOW
COVER...WITH SINGLE DIGITS MIN EXPECTED OVR SOME OF THE SNOW FIELD
THE NXT CPL NIGHTS.
TRUETT
&&
.AVIATION...
FOR THE 12Z TAFS...
TAFS WILL REFLECT RAPID IMPROVEMENT BETWEEN 12-15Z THIS MORNING AS
SYSTEM LIFTS OUT OF AREA. ANALYSIS OF CIGS/VSBYS SHOW THAT ONCE THE
SNOW LETS UP...VFR CONDITIONS FOLLOW QUICKLY. HAVE ADDED SOME
BLSN SNOW TO THE TAFS THIS MORNING AS NEW SNOW IS BEING BLOWN
AROUND BY GUSTY WINDS. THE WINDS WILL DIMINISH THIS MORNING AS THE
SFC LOW RACES NEWD CAUSING THE PRESSURE GRADIENT TO WEAKEN. WINDS
WILL CONTINUE TO LIGHTEN UP INTO THE EVENING HOURS WITH SKC.
BRITT
&&
.LSX WATCHES/WARNINGS/ADVISORIES...
MO...WINTER STORM WARNING UNTIL NOON CST TODAY FOR AUDRAIN-BOONE-
CALLAWAY-COLE-CRAWFORD-FRANKLIN-GASCONADE-IRON-JEFFERSON-
KNOX-LEWIS-LINCOLN-MADISON-MARION-MONITEAU-MONROE-
MONTGOMERY-OSAGE-PIKE-RALLS-REYNOLDS-SHELBY-ST.
CHARLES-ST.
FRANCOIS-ST. LOUIS-ST. LOUIS CITY-STE.
GENEVIEVE-WARREN-
WASHINGTON.
IL...WINTER STORM WARNING UNTIL NOON CST TODAY FOR ADAMS IL-BOND IL-
BROWN IL-CALHOUN IL-CLINTON IL-FAYETTE IL-GREENE
IL-JERSEY
IL-MACOUPIN IL-MADISON IL-MARION IL-MONROE
IL-MONTGOMERY IL-
PIKE IL-RANDOLPH IL-ST. CLAIR IL-WASHINGTON IL.
&&
$$
WFO LSX
FXUS63 KLSX 011504
AFDLSX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE ST LOUIS MO
903 AM CST FRI DEC 1 2006
.UPDATE...
HAVE CANCELLED THE WINTER STORM WARNING OVER MOST OF THE COUNTIES
AS STORM IS MOVING RAPIDLY OFF TO THE NORTHEAST. HAVE KEPT IT
GOING IN PARTS OF THE NERN CWA WHERE IT IS STILL SNOWING...AND
THESE COUNTIES MAY STILL BE SEEING SOME CONSIDERABLE BLOWING AND
DRIFTING UNTIL NOON. OTHER AREAS MAY STILL SEE SOME MINOR BLOWING
AND DRIFTING UNTIL THE PRESSURE GRADIENT WEAKENS LATER THIS
MORNING/AFTN.
BRITT/TRUETT
&&
.DISCUSSION...
...WINTER STORM PARALYZING MUCH OF BI-STATE REGION THIS MORNING...
FIRST WINTER STORM OF THE 2006-07 SEASON IS CERTAINLY TURNING OUT TO
BE AN EXTREMLY POTENT SYSTEM. INTS UPR LVL LO SPINNING INTO S CNTRL
MO SET UP DEFORMATION ZN FROM JUST N OF KJLN...THRU KCOU...TO NR
KUIN OVRNGT. ENHACING THE HEAVY SNOWFALL THAT IS TYPICAL WITH THE
DEF ZN...SPOTTY CNVTN NR KCOU HAS BEEN PRODUCING SNOWFALL RATES OF
UP TO 3"/HR. KOMU TV REPORTS 11 INCHES OF SNOW ON THE
GROUND...WITH DRIFTS OF NEARLY 2 FEET. MODOT AS ALSO SUSPENDED
PLOWING OPERATIONS IN MID MO...AND PARTS OF I-70 ARE CLOSED.
FURTHER E...ROUGHLY ON AND EAST OF THE I-44/I-70 CORRIDOR...SVR
ICING IS THE MAJOR PROBLEM...WITH AN ICY MIX OF SLEET AND FREEZING
RAIN THAT BEGAN THU MRNG AND PERSISTED INTO LATE THU EVE. PCPN IN
THIS ZONE FINALLY BEGAN THE CHGOVER TO SNOW OVR THE LAST FEW HRS.
POWER OUTAGES ARE COMMON...AND POWER IS NOW OUT TO OVER 150,000
CUSTOMERS IN STL METRO AREA.
WITH UPR LO ON THE MOVE...THINK PCPN ACR CWA WL BE WINDING DOWN
FAIRLY QUICKLY IN THE 12Z-15Z TIME FRAME...ALTHO XTRMLY HVY SNOW
NOW FALLING OVR MID MO WL BE PUSHING INTO KUIN AREA BTWN NOW AND
12Z QUICKLY ADDING TO THE ACCUMULATIONS IN THIS AREA BY DAYBREAK.
STL METRO WL PROBABLY BE ON THE E EDGE OF THE HVIEST ACCUMULATIONS...BUT
THINK THE HEAVIEST SNOWFALL FOR THIS AREA IS STILL IN THE OFFING
OVR THE NXT CPL OF HRS. MSTR WRAPPING N OF LO IS CAUSING BANDS OF
LGT/MDT SNW TO REFORM S OF MAIN DEFZN...AND THINK AREA WL SEE SVRL
SHOTS OF MDT/HVY SNOW BTWN NOW AND 12Z...WITH THE PRIMARY IMPACT
OF THIS SNOW OCRG W AND N OF DOWNTOWN.
AS FAR AS TOTAL SNOWFALL IS CONCERNED...SM LOCATIONS ALG THE KCOU-
KUIN LN WL TOP 12-14 INCHES...WHILE FAR E COUNTIES WL LIKELY PICK
UP AN INCH OR SO.
HWVR...WITH WINDS PICKING UP WX PROBLEMS SHUD PERSIST PAST THE END OF
THE PCPN. IN THE HVY SNOWFALL AREAS...FROM CNTRL MO INTO W CNTRL
IL...BLOWING AND DRIFTING WL BE A PROBLEM...WHILE IN THE I-44/I-70
CORRIDOR AM XTRMLY CONCERNED THAT POWER OUTAGES WL BCM EVEN MORE
WIDESPREAD AS THE SFC LO PULLS E AND NW WINDS INCR. BECAUSE OF
THIS...WL EXTEND THE WINTER STORM WARNING FOR ENTR AREA UNTIL 18Z.
GENLY DRY AND COLD CONDS FCST FOR RMNDR OF SHORT TERM PD. FOLLOWED
LEAD OF ERYR FCSTS AND TRIMMED BACK TEMPS EVEN MORE IN DEEP SNOW
COVER...WITH SINGLE DIGITS MIN EXPECTED OVR SOME OF THE SNOW FIELD
THE NXT CPL NIGHTS.
TRUETT
&&
.AVIATION...
FOR THE 12Z TAFS...
TAFS WILL REFLECT RAPID IMPROVEMENT BETWEEN 12-15Z THIS MORNING AS
SYSTEM LIFTS OUT OF AREA. ANALYSIS OF CIGS/VSBYS SHOW THAT ONCE THE
SNOW LETS UP...VFR CONDITIONS FOLLOW QUICKLY. HAVE ADDED SOME
BLSN SNOW TO THE TAFS THIS MORNING AS NEW SNOW IS BEING BLOWN
AROUND BY GUSTY WINDS. THE WINDS WILL DIMINISH THIS MORNING AS THE
SFC LOW RACES NEWD CAUSING THE PRESSURE GRADIENT TO WEAKEN. WINDS
WILL CONTINUE TO LIGHTEN UP INTO THE EVENING HOURS WITH SKC.
BRITT
&&
.LSX WATCHES/WARNINGS/ADVISORIES...
MO...NONE.
IL...WINTER STORM WARNING UNTIL NOON CST TODAY FOR GREENE IL-JERSEY
IL-MACOUPIN IL-MONTGOMERY IL.
&&
$$
WFO LSX
FXUS63 KLSX 011638
AFDLSX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE ST LOUIS MO
1038 AM CST FRI DEC 1 2006
.UPDATE...
HAVE CANCELLED THE LAST REMAINING PIECE OF THE WINTER STORM
WARNING AS THE FINAL SNOW BAND HAS PUSHED WELL EAST. STILL SEEING
SOME BLOWING SNOW AND DRIFTING SNOW FROM CENTRAL AND NRN MO THRU
WEST CENTRAL ILLINOIS.
QUITE A STORM WITH PROLONGED SLEET AND ICE FROM THE STL AREA SOUTH
AND EAST RESULTING IN WIDESPREAD POWER OUTAGES...AND THUNDERSNOW
CONTRIBUTING TO 12+ INCHES OF SNOW FROM CENTRAL MO INTO WCNTRL IL.
GLASS
&&
.PREVIOUS DISCUSSION...
...WINTER STORM PARALYZING MUCH OF BI-STATE REGION THIS MORNING...
FIRST WINTER STORM OF THE 2006-07 SEASON IS CERTAINLY TURNING OUT TO
BE AN EXTREMLY POTENT SYSTEM. INTS UPR LVL LO SPINNING INTO S CNTRL
MO SET UP DEFORMATION ZN FROM JUST N OF KJLN...THRU KCOU...TO NR
KUIN OVRNGT. ENHACING THE HEAVY SNOWFALL THAT IS TYPICAL WITH THE
DEF ZN...SPOTTY CNVTN NR KCOU HAS BEEN PRODUCING SNOWFALL RATES OF
UP TO 3"/HR. KOMU TV REPORTS 11 INCHES OF SNOW ON THE
GROUND...WITH DRIFTS OF NEARLY 2 FEET. MODOT AS ALSO SUSPENDED
PLOWING OPERATIONS IN MID MO...AND PARTS OF I-70 ARE CLOSED.
FURTHER E...ROUGHLY ON AND EAST OF THE I-44/I-70 CORRIDOR...SVR
ICING IS THE MAJOR PROBLEM...WITH AN ICY MIX OF SLEET AND FREEZING
RAIN THAT BEGAN THU MRNG AND PERSISTED INTO LATE THU EVE. PCPN IN
THIS ZONE FINALLY BEGAN THE CHGOVER TO SNOW OVR THE LAST FEW HRS.
POWER OUTAGES ARE COMMON...AND POWER IS NOW OUT TO OVER 150,000
CUSTOMERS IN STL METRO AREA.
WITH UPR LO ON THE MOVE...THINK PCPN ACR CWA WL BE WINDING DOWN
FAIRLY QUICKLY IN THE 12Z-15Z TIME FRAME...ALTHO XTRMLY HVY SNOW
NOW FALLING OVR MID MO WL BE PUSHING INTO KUIN AREA BTWN NOW AND
12Z QUICKLY ADDING TO THE ACCUMULATIONS IN THIS AREA BY DAYBREAK.
STL METRO WL PROBABLY BE ON THE E EDGE OF THE HVIEST ACCUMULATIONS...BUT
THINK THE HEAVIEST SNOWFALL FOR THIS AREA IS STILL IN THE OFFING
OVR THE NXT CPL OF HRS. MSTR WRAPPING N OF LO IS CAUSING BANDS OF
LGT/MDT SNW TO REFORM S OF MAIN DEFZN...AND THINK AREA WL SEE SVRL
SHOTS OF MDT/HVY SNOW BTWN NOW AND 12Z...WITH THE PRIMARY IMPACT
OF THIS SNOW OCRG W AND N OF DOWNTOWN.
AS FAR AS TOTAL SNOWFALL IS CONCERNED...SM LOCATIONS ALG THE KCOU-
KUIN LN WL TOP 12-14 INCHES...WHILE FAR E COUNTIES WL LIKELY PICK
UP AN INCH OR SO.
HWVR...WITH WINDS PICKING UP WX PROBLEMS SHUD PERSIST PAST THE END OF
THE PCPN. IN THE HVY SNOWFALL AREAS...FROM CNTRL MO INTO W CNTRL
IL...BLOWING AND DRIFTING WL BE A PROBLEM...WHILE IN THE I-44/I-70
CORRIDOR AM XTRMLY CONCERNED THAT POWER OUTAGES WL BCM EVEN MORE
WIDESPREAD AS THE SFC LO PULLS E AND NW WINDS INCR. BECAUSE OF
THIS...WL EXTEND THE WINTER STORM WARNING FOR ENTR AREA UNTIL 18Z.
GENLY DRY AND COLD CONDS FCST FOR RMNDR OF SHORT TERM PD. FOLLOWED
LEAD OF ERYR FCSTS AND TRIMMED BACK TEMPS EVEN MORE IN DEEP SNOW
COVER...WITH SINGLE DIGITS MIN EXPECTED OVR SOME OF THE SNOW FIELD
THE NXT CPL NIGHTS.
TRUETT
&&
.AVIATION...
FOR THE 12Z TAFS...
TAFS WILL REFLECT RAPID IMPROVEMENT BETWEEN 12-15Z THIS MORNING AS
SYSTEM LIFTS OUT OF AREA. ANALYSIS OF CIGS/VSBYS SHOW THAT ONCE THE
SNOW LETS UP...VFR CONDITIONS FOLLOW QUICKLY. HAVE ADDED SOME
BLSN SNOW TO THE TAFS THIS MORNING AS NEW SNOW IS BEING BLOWN
AROUND BY GUSTY WINDS. THE WINDS WILL DIMINISH THIS MORNING AS THE
SFC LOW RACES NEWD CAUSING THE PRESSURE GRADIENT TO WEAKEN. WINDS
WILL CONTINUE TO LIGHTEN UP INTO THE EVENING HOURS WITH SKC.
BRITT
&&
.LSX WATCHES/WARNINGS/ADVISORIES...
MO...NONE.
IL...NONE.
&&
$$
WFO LSX
FXUS63 KLSX 011733
AFDLSX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE ST LOUIS MO
1133 AM CST FRI DEC 1 2006
.UPDATE...
HAVE CANCELLED THE LAST REMAINING PIECE OF THE WINTER STORM
WARNING AS THE FINAL SNOW BAND HAS PUSHED WELL EAST. STILL SEEING
SOME BLOWING SNOW AND DRIFTING SNOW FROM CENTRAL AND NRN MO THRU
WEST CENTRAL ILLINOIS.
QUITE A STORM WITH PROLONGED SLEET AND ICE FROM THE STL AREA SOUTH
AND EAST RESULTING IN WIDESPREAD POWER OUTAGES...AND THUNDERSNOW
CONTRIBUTING TO 12+ INCHES OF SNOW FROM CENTRAL MO INTO WCNTRL IL.
GLASS
&&
.DISCUSSION...
NONE
&&
.AVIATION...
FOR THE 18Z TAFS...THE BACK EDGE OF STRATUS WAS LOCATED FROM NEAR
KUIN TO JUST WEST OF KSUS/KSTL AT 1715Z. SATELLITE TRENDS SUGGEST
MVFR CIGS WILL CONTINUE TO IMPACT THESE TAF SITES FOR ANOTHER HOUR
OR SO AS THE CLOUDS CLEAR TO THE EAST. SFC PRESSURE GRADIENT ALSO
RELAXING SOME AND THUS WIND GUSTS SHOULD BE ABOUT DONE. WEAK SFC
RIDGE MOVES INTO THE REGION TONIGHT WITH WINDS BECOMING LIGHT AND
VEERING TO MORE SWLY. SOME SCT-BKN MID-HI CLOUDS WILL FILTER
ACROSS THE REGION TONIGHT INTO SATURDAY MORNING.
GLASS
&&
.LSX WATCHES/WARNINGS/ADVISORIES...
MO...NONE.
IL...NONE.
&&
$$
WFO LSX
FXUS63 KLSX 011738
AFDLSX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE ST LOUIS MO
1138 AM CST FRI DEC 1 2006
.UPDATE...
HAVE CANCELLED THE LAST REMAINING PIECE OF THE WINTER STORM
WARNING AS THE FINAL SNOW BAND HAS PUSHED WELL EAST. STILL SEEING
SOME BLOWING SNOW AND DRIFTING SNOW FROM CENTRAL AND NRN MO THRU
WEST CENTRAL ILLINOIS.
QUITE A STORM WITH PROLONGED SLEET AND ICE FROM THE STL AREA SOUTH
AND EAST RESULTING IN WIDESPREAD POWER OUTAGES...AND THUNDERSNOW
CONTRIBUTING TO 12+ INCHES OF SNOW FROM CENTRAL MO INTO WCNTRL IL.
GLASS
&&
.DISCUSSION...
...WINTER STORM PARALYZING MUCH OF BI-STATE REGION THIS MORNING...
FIRST WINTER STORM OF THE 2006-07 SEASON IS CERTAINLY TURNING OUT TO
BE AN EXTREMLY POTENT SYSTEM. INTS UPR LVL LO SPINNING INTO S CNTRL
MO SET UP DEFORMATION ZN FROM JUST N OF KJLN...THRU KCOU...TO NR
KUIN OVRNGT. ENHACING THE HEAVY SNOWFALL THAT IS TYPICAL WITH THE
DEF ZN...SPOTTY CNVTN NR KCOU HAS BEEN PRODUCING SNOWFALL RATES OF
UP TO 3"/HR. KOMU TV REPORTS 11 INCHES OF SNOW ON THE
GROUND...WITH DRIFTS OF NEARLY 2 FEET. MODOT AS ALSO SUSPENDED
PLOWING OPERATIONS IN MID MO...AND PARTS OF I-70 ARE CLOSED.
FURTHER E...ROUGHLY ON AND EAST OF THE I-44/I-70 CORRIDOR...SVR
ICING IS THE MAJOR PROBLEM...WITH AN ICY MIX OF SLEET AND FREEZING
RAIN THAT BEGAN THU MRNG AND PERSISTED INTO LATE THU EVE. PCPN IN
THIS ZONE FINALLY BEGAN THE CHGOVER TO SNOW OVR THE LAST FEW HRS.
POWER OUTAGES ARE COMMON...AND POWER IS NOW OUT TO OVER 150,000
CUSTOMERS IN STL METRO AREA.
WITH UPR LO ON THE MOVE...THINK PCPN ACR CWA WL BE WINDING DOWN
FAIRLY QUICKLY IN THE 12Z-15Z TIME FRAME...ALTHO XTRMLY HVY SNOW
NOW FALLING OVR MID MO WL BE PUSHING INTO KUIN AREA BTWN NOW AND
12Z QUICKLY ADDING TO THE ACCUMULATIONS IN THIS AREA BY DAYBREAK.
STL METRO WL PROBABLY BE ON THE E EDGE OF THE HVIEST ACCUMULATIONS...BUT
THINK THE HEAVIEST SNOWFALL FOR THIS AREA IS STILL IN THE OFFING
OVR THE NXT CPL OF HRS. MSTR WRAPPING N OF LO IS CAUSING BANDS OF
LGT/MDT SNW TO REFORM S OF MAIN DEFZN...AND THINK AREA WL SEE SVRL
SHOTS OF MDT/HVY SNOW BTWN NOW AND 12Z...WITH THE PRIMARY IMPACT
OF THIS SNOW OCRG W AND N OF DOWNTOWN.
AS FAR AS TOTAL SNOWFALL IS CONCERNED...SM LOCATIONS ALG THE KCOU-
KUIN LN WL TOP 12-14 INCHES...WHILE FAR E COUNTIES WL LIKELY PICK
UP AN INCH OR SO.
HWVR...WITH WINDS PICKING UP WX PROBLEMS SHUD PERSIST PAST THE END OF
THE PCPN. IN THE HVY SNOWFALL AREAS...FROM CNTRL MO INTO W CNTRL
IL...BLOWING AND DRIFTING WL BE A PROBLEM...WHILE IN THE I-44/I-70
CORRIDOR AM XTRMLY CONCERNED THAT POWER OUTAGES WL BCM EVEN MORE
WIDESPREAD AS THE SFC LO PULLS E AND NW WINDS INCR. BECAUSE OF
THIS...WL EXTEND THE WINTER STORM WARNING FOR ENTR AREA UNTIL 18Z.
GENLY DRY AND COLD CONDS FCST FOR RMNDR OF SHORT TERM PD. FOLLOWED
LEAD OF ERYR FCSTS AND TRIMMED BACK TEMPS EVEN MORE IN DEEP SNOW
COVER...WITH SINGLE DIGITS MIN EXPECTED OVR SOME OF THE SNOW FIELD
THE NXT CPL NIGHTS.
TRUETT
&&
.AVIATION...
FOR THE 18Z TAFS...THE BACK EDGE OF STRATUS WAS LOCATED FROM NEAR
KUIN TO JUST WEST OF KSUS/KSTL AT 1715Z. SATELLITE TRENDS SUGGEST
MVFR CIGS WILL CONTINUE TO IMPACT THESE TAF SITES FOR ANOTHER HOUR
OR SO AS THE CLOUDS CLEAR TO THE EAST. SFC PRESSURE GRADIENT ALSO
RELAXING SOME AND THUS WIND GUSTS SHOULD BE ABOUT DONE. WEAK SFC
RIDGE MOVES INTO THE REGION TONIGHT WITH WINDS BECOMING LIGHT AND
VEERING TO MORE SWLY. SOME SCT-BKN MID-HI CLOUDS WILL FILTER
ACROSS THE REGION TONIGHT INTO SATURDAY MORNING.
GLASS
&&
.LSX WATCHES/WARNINGS/ADVISORIES...
MO...NONE.
IL...NONE.
&&
$$
WFO LSX
FXUS63 KLSX 012152
AFDLSX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE ST LOUIS MO
352 PM CST FRI DEC 1 2006
.DISCUSSION...
THE 12Z SHORT-TERM MODELS (TIL MONDAY)...MODELS IN GOOD AGREEMENT ON
THE H500 PATTERN DURING THIS TIME...WITH ZONAL TRANSITIONARY FLOW
FORECAST FOR THE CNTRL CONUS EARLY IN THE PERIOD...BEFORE TROF CAN
RE-ASSERT ITSELF ACROSS THE AREA DURING THE WEEKEND VIA A PAIR OF
STRONG VORT CENTERS ON ITS BACKSIDE. THESE VORT CENTERS...ONE
NORTHERN STREAM AND THE OTHER A SOUTHERN STREAM...WILL ATTEMPT TO
MERGE AND BE MORE IN-PHASE OVER THE MID MS VALLEY ON SUNDAY...BUT
THIS VARIES TO ONE DEGREE OR ANOTHER DEPENDING ON WHICH MODEL ONE
LOOKS AT...BUT ALL MODELS DO SHOW THIS ATTEMPTED COMING TOGETHER OF
THE NRN AND SRN STREAM SYSTEMS ON SUNDAY...OR IN THE CASE OF THE
NAM...CONTINUING INTO SUNDAY NIGHT. AT THE SURFACE...HI PRES RDG TO
HANG AROUND IN SRN MO/SRN IL TONIGHT AND EARLY SATURDAY BEFORE
GIVING WAY TO NEXT STRONG CDFNT LATE SATURDAY AFTERNOON/EVENING.
ARCTIC HI PRES WILL THEN BUILD INTO AREA ON SUNDAY WITH AREA QUICKLY
ENDING UP ON ITS BACKSIDE BY MONDAY. NAM DELAYS THIS SOMEWHAT...BUT
LOOKING MORE CLOSELY...SHOWS MUCH STRONGER CENTER OF 1050MB VERSUS
OTHER MODELS SHOWING 1044MB...AND THIS IS ANOMALOUS WHEN COMPARED TO
INITIAL HI PRES STRENGTH IN NWRN CANADA. PREFER GFS/UKMET SOLUTION
HERE.
WX WILL BE QUIET OVER THE NEXT FEW DAYS...BUT EFFECTS FROM PREVIOUS
36HRS OF WINTER STORM WILL BE FELT THRU THIS PERIOD. RATHER HEFTY
SNOW PACK WAS DEPOSITED FROM W CNTRL IL/NERN MO THRU CNTRL MO WHERE
9 TO 16 INCHES EXISTED DURING MID MORNING AND LESSER AMOUNTS FURTHER
SEWD...WITH ONLY TRACE AMOUNTS IN PARTS OF SERN MO AND SRN IL.
NEEDLESS TO SAY...IN GENERAL ABSENCE OF STRONG WARM ADVECTION
PATTERNS...AREA OF DEEPEST SNOW PACK WILL ALLOW TEMPERATURES TO
FREEFALL AT NIGHT AND HOLD THEM BACK DURING THE DAY. WITH MOS NOT
QUITE FULLY REGISTERING THE SCOPE OF THE WINTER STORM YET...
OPPORTUNITIES ABOUND FOR BIG GAINS/IMPROVEMENTS ON TEMP FORECASTS
STARTING WITH TONIGHT WHERE MOS AVERAGE SHOWING UPPER TEENS/AROUND
20F FOR KUIN/KCOU...AND TEMPS ARE CURRENTLY 22F! LIGHT SWLY SFC WNDS
WILL DO LITTLE TO WARM THINGS UP TONIGHT OVER THE DEEP SNOW PACK
SINCE THIS WILL PARALLEL IT AND INSTEAD RESULT IN CAA. WENT FOR
5-10F FOR MINS FOR THIS AREA...WITH WARMER TEMPS SEWD WHERE LESSER
AMOUNTS OF SNOW PACK WILL LESSEN THE EFFECTS...EDGING TOWARDS THE
COLDEST MOS TEMPS.
CONTINUED THIS TREND FOR THE NEXT TWO NIGHTS...LESSENING THINGS A
BIT FOR EACH NIGHT...BUT WITH NEXT CANADIAN AIRMASS DUE IN BY LATE
SATURDAY NIGHT ANYWAY...TEMPS WILL CONTINUE TO FALL INTO THE SINGLE
DIGITS FOR THE DEEP SNOW PACK AREAS.
ALSO SEE CHANCE FOR LARGE IMPROVEMENT TO MAX TEMPS...ESPECIALLY ON
SATURDAY WHERE MOS HAS 40S FOR MANY AREAS. HAVE TRIMMED TO 30S
INSTEAD...ESPECIALLY CONSIDERING THE VERY LOW READINGS EARLY IN THE
DAY. TEMPERED THESE ADJUSTMENTS HEADING OUT IN TIME FOR SUNDAY AND
MONDAY.
FOR THE EXTENDED PERIOD (MONDAY NIGHT - FRIDAY)...NWP MODELS ARE IN
REASONABLE AGREEMENT ON AMPLIFIED H500 PATTERN DURING THIS PERIOD...
WITH LONGWAVE TROF OVER ERN NOAM AND RIDGE OVER WRN NOAM RESULTING
IN NWLY FLOW FOR THE MID MS VALLEY. IN ADDITION...MODELS SHOW RATHER
STRONG SHORTWAVE DIGGING THRU THE CNTRL CONUS DURING MID WEEK BUT
DISAGREE AS TO ITS INTENSITY AND TIMING. THE 12Z GFS HAS TRENDED FOR
A TIMING OF THURSDAY BUT ALSO SHOWING A WEAKER...MORE OPEN WAVE...
THAN IT WAS SHOWING FROM THE 00Z/06Z RUNS. THIS SEEMS TO BE MORE IN
LINE WITH THE ECMWF AND UKMET. AT THE SURFACE...ONE COLD HI PRES TO
EXIT EARLY IN THE PERIOD...BEFORE ANOTHER STRONG COLD FRONT MOVES
THRU DURING TUESDAY/WEDNESDAY TIMEFRAME...WITH THE BUILDING COLD HI
PRES DOMINATING THE AREA FOR LATE WEEK. MAIN BONE OF CONTENTION IS
WITH THE TIMING...AS GFS IS ABOUT 12HRS FASTER THAN ECMWF AND NEARLY
24HRS FASTER THAN THE UKMET. GIVEN ECMWF HAS A BETTER VERIFICATION
HISTORY OUT IN THE MEDIUM RANGE THAN THE GFS...PREFER TO ADJUST THE
GFS PER A SLOWER ARRIVAL OF CDFNT. OVERALL AM EXPECTING A DRY
FORECAST DURING THIS PERIOD AS MOISTURE WILL BE IN LIMITED SUPPLY AS
THE FA SIMPLY EXCHANGES ONE COLD DRY AIRMASS FOR ANOTHER. STRONG
SHORTWAVE FOR MID-LATE WEEK MAY DELIVER A LOW POTENTIAL FOR
PCPN...BUT UNCERTAINTY ON ITS TRACK AND FACT THAT COLD HI PRES AT
THE LO LEVELS WILL BE UNDERCUTTING IT...DOES NOT BODE WELL FOR PCPN
CHANCES. HAVE LEFT DRY FOR NOW. TEMPERATURES TO BE BELOW NORMAL
THROUGH THE PERIOD.
TES
&&
.AVIATION...
FOR THE 18Z TAFS...THE BACK EDGE OF STRATUS WAS LOCATED FROM NEAR
KUIN TO JUST WEST OF KSUS/KSTL AT 1715Z. SATELLITE TRENDS SUGGEST
MVFR CIGS WILL CONTINUE TO IMPACT THESE TAF SITES FOR ANOTHER HOUR
OR SO AS THE CLOUDS CLEAR TO THE EAST. SFC PRESSURE GRADIENT ALSO
RELAXING SOME AND THUS WIND GUSTS SHOULD BE ABOUT DONE. WEAK SFC
RIDGE MOVES INTO THE REGION TONIGHT WITH WINDS BECOMING LIGHT AND
VEERING TO MORE SWLY. SOME SCT-BKN MID-HI CLOUDS WILL FILTER
ACROSS THE REGION TONIGHT INTO SATURDAY MORNING.
GLASS
&&
.LSX WATCHES/WARNINGS/ADVISORIES...
MO...NONE.
IL...NONE.
&&
$$
WFO LSX
FXUS63 KLSX 020009
AFDLSX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE ST LOUIS MO
609 PM CST FRI DEC 1 2006
.DISCUSSION...
THE 12Z SHORT-TERM MODELS (TIL MONDAY)...MODELS IN GOOD AGREEMENT ON
THE H500 PATTERN DURING THIS TIME...WITH ZONAL TRANSITIONARY FLOW
FORECAST FOR THE CNTRL CONUS EARLY IN THE PERIOD...BEFORE TROF CAN
RE-ASSERT ITSELF ACROSS THE AREA DURING THE WEEKEND VIA A PAIR OF
STRONG VORT CENTERS ON ITS BACKSIDE. THESE VORT CENTERS...ONE
NORTHERN STREAM AND THE OTHER A SOUTHERN STREAM...WILL ATTEMPT TO
MERGE AND BE MORE IN-PHASE OVER THE MID MS VALLEY ON SUNDAY...BUT
THIS VARIES TO ONE DEGREE OR ANOTHER DEPENDING ON WHICH MODEL ONE
LOOKS AT...BUT ALL MODELS DO SHOW THIS ATTEMPTED COMING TOGETHER OF
THE NRN AND SRN STREAM SYSTEMS ON SUNDAY...OR IN THE CASE OF THE
NAM...CONTINUING INTO SUNDAY NIGHT. AT THE SURFACE...HI PRES RDG TO
HANG AROUND IN SRN MO/SRN IL TONIGHT AND EARLY SATURDAY BEFORE
GIVING WAY TO NEXT STRONG CDFNT LATE SATURDAY AFTERNOON/EVENING.
ARCTIC HI PRES WILL THEN BUILD INTO AREA ON SUNDAY WITH AREA QUICKLY
ENDING UP ON ITS BACKSIDE BY MONDAY. NAM DELAYS THIS SOMEWHAT...BUT
LOOKING MORE CLOSELY...SHOWS MUCH STRONGER CENTER OF 1050MB VERSUS
OTHER MODELS SHOWING 1044MB...AND THIS IS ANOMALOUS WHEN COMPARED TO
INITIAL HI PRES STRENGTH IN NWRN CANADA. PREFER GFS/UKMET SOLUTION
HERE.
WX WILL BE QUIET OVER THE NEXT FEW DAYS...BUT EFFECTS FROM PREVIOUS
36HRS OF WINTER STORM WILL BE FELT THRU THIS PERIOD. RATHER HEFTY
SNOW PACK WAS DEPOSITED FROM W CNTRL IL/NERN MO THRU CNTRL MO WHERE
9 TO 16 INCHES EXISTED DURING MID MORNING AND LESSER AMOUNTS FURTHER
SEWD...WITH ONLY TRACE AMOUNTS IN PARTS OF SERN MO AND SRN IL.
NEEDLESS TO SAY...IN GENERAL ABSENCE OF STRONG WARM ADVECTION
PATTERNS...AREA OF DEEPEST SNOW PACK WILL ALLOW TEMPERATURES TO
FREEFALL AT NIGHT AND HOLD THEM BACK DURING THE DAY. WITH MOS NOT
QUITE FULLY REGISTERING THE SCOPE OF THE WINTER STORM YET...
OPPORTUNITIES ABOUND FOR BIG GAINS/IMPROVEMENTS ON TEMP FORECASTS
STARTING WITH TONIGHT WHERE MOS AVERAGE SHOWING UPPER TEENS/AROUND
20F FOR KUIN/KCOU...AND TEMPS ARE CURRENTLY 22F! LIGHT SWLY SFC WNDS
WILL DO LITTLE TO WARM THINGS UP TONIGHT OVER THE DEEP SNOW PACK
SINCE THIS WILL PARALLEL IT AND INSTEAD RESULT IN CAA. WENT FOR
5-10F FOR MINS FOR THIS AREA...WITH WARMER TEMPS SEWD WHERE LESSER
AMOUNTS OF SNOW PACK WILL LESSEN THE EFFECTS...EDGING TOWARDS THE
COLDEST MOS TEMPS.
CONTINUED THIS TREND FOR THE NEXT TWO NIGHTS...LESSENING THINGS A
BIT FOR EACH NIGHT...BUT WITH NEXT CANADIAN AIRMASS DUE IN BY LATE
SATURDAY NIGHT ANYWAY...TEMPS WILL CONTINUE TO FALL INTO THE SINGLE
DIGITS FOR THE DEEP SNOW PACK AREAS.
ALSO SEE CHANCE FOR LARGE IMPROVEMENT TO MAX TEMPS...ESPECIALLY ON
SATURDAY WHERE MOS HAS 40S FOR MANY AREAS. HAVE TRIMMED TO 30S
INSTEAD...ESPECIALLY CONSIDERING THE VERY LOW READINGS EARLY IN THE
DAY. TEMPERED THESE ADJUSTMENTS HEADING OUT IN TIME FOR SUNDAY AND
MONDAY.
FOR THE EXTENDED PERIOD (MONDAY NIGHT - FRIDAY)...NWP MODELS ARE IN
REASONABLE AGREEMENT ON AMPLIFIED H500 PATTERN DURING THIS PERIOD...
WITH LONGWAVE TROF OVER ERN NOAM AND RIDGE OVER WRN NOAM RESULTING
IN NWLY FLOW FOR THE MID MS VALLEY. IN ADDITION...MODELS SHOW RATHER
STRONG SHORTWAVE DIGGING THRU THE CNTRL CONUS DURING MID WEEK BUT
DISAGREE AS TO ITS INTENSITY AND TIMING. THE 12Z GFS HAS TRENDED FOR
A TIMING OF THURSDAY BUT ALSO SHOWING A WEAKER...MORE OPEN WAVE...
THAN IT WAS SHOWING FROM THE 00Z/06Z RUNS. THIS SEEMS TO BE MORE IN
LINE WITH THE ECMWF AND UKMET. AT THE SURFACE...ONE COLD HI PRES TO
EXIT EARLY IN THE PERIOD...BEFORE ANOTHER STRONG COLD FRONT MOVES
THRU DURING TUESDAY/WEDNESDAY TIMEFRAME...WITH THE BUILDING COLD HI
PRES DOMINATING THE AREA FOR LATE WEEK. MAIN BONE OF CONTENTION IS
WITH THE TIMING...AS GFS IS ABOUT 12HRS FASTER THAN ECMWF AND NEARLY
24HRS FASTER THAN THE UKMET. GIVEN ECMWF HAS A BETTER VERIFICATION
HISTORY OUT IN THE MEDIUM RANGE THAN THE GFS...PREFER TO ADJUST THE
GFS PER A SLOWER ARRIVAL OF CDFNT. OVERALL AM EXPECTING A DRY
FORECAST DURING THIS PERIOD AS MOISTURE WILL BE IN LIMITED SUPPLY AS
THE FA SIMPLY EXCHANGES ONE COLD DRY AIRMASS FOR ANOTHER. STRONG
SHORTWAVE FOR MID-LATE WEEK MAY DELIVER A LOW POTENTIAL FOR
PCPN...BUT UNCERTAINTY ON ITS TRACK AND FACT THAT COLD HI PRES AT
THE LO LEVELS WILL BE UNDERCUTTING IT...DOES NOT BODE WELL FOR PCPN
CHANCES. HAVE LEFT DRY FOR NOW. TEMPERATURES TO BE BELOW NORMAL
THROUGH THE PERIOD.
TES
&&
.AVIATION...
FOR THE 00Z TAFS...MUCH MORE TRANQUIL WX THIS FCST PD. SFC RDG
EXTDG FM ERN OK SE THRU NRN MS WL MOV EWD. W-SWLY SFC WNDS CAN BE
EXPECTED TGT AND SAT MRNG ACRS THE CWA JUST N OF THE SFC RDG. A
DRY CDFNT WILL BE PUSHING SEWD THRU UIN AND COU SAT AFTN WITH THE
SWLY SFC WNDS VEERING ARND TO THE NW BHND THE CDFNT. MID LVL
CLOUDINESS WILL BE MOVG EWD INTO THE CWA LT TGT AND SAT AS MDLS
DEPICT INCRSG RH BTWN 700-400 MB AFT 06Z SAT. WILL INCLUDE SCT-
BKN120 FOR SKY CONDITION IN THE TAFS MAINLY ON SAT.
GKS
&&
.LSX WATCHES/WARNINGS/ADVISORIES...
MO...NONE.
IL...NONE.
&&
$$
WFO LSX
FXUS63 KLSX 020516
AFDLSX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE ST LOUIS MO
1116 PM CST FRI DEC 1 2006
.DISCUSSION...
THE 12Z SHORT-TERM MODELS (TIL MONDAY)...MODELS IN GOOD AGREEMENT ON
THE H500 PATTERN DURING THIS TIME...WITH ZONAL TRANSITIONARY FLOW
FORECAST FOR THE CNTRL CONUS EARLY IN THE PERIOD...BEFORE TROF CAN
RE-ASSERT ITSELF ACROSS THE AREA DURING THE WEEKEND VIA A PAIR OF
STRONG VORT CENTERS ON ITS BACKSIDE. THESE VORT CENTERS...ONE
NORTHERN STREAM AND THE OTHER A SOUTHERN STREAM...WILL ATTEMPT TO
MERGE AND BE MORE IN-PHASE OVER THE MID MS VALLEY ON SUNDAY...BUT
THIS VARIES TO ONE DEGREE OR ANOTHER DEPENDING ON WHICH MODEL ONE
LOOKS AT...BUT ALL MODELS DO SHOW THIS ATTEMPTED COMING TOGETHER OF
THE NRN AND SRN STREAM SYSTEMS ON SUNDAY...OR IN THE CASE OF THE
NAM...CONTINUING INTO SUNDAY NIGHT. AT THE SURFACE...HI PRES RDG TO
HANG AROUND IN SRN MO/SRN IL TONIGHT AND EARLY SATURDAY BEFORE
GIVING WAY TO NEXT STRONG CDFNT LATE SATURDAY AFTERNOON/EVENING.
ARCTIC HI PRES WILL THEN BUILD INTO AREA ON SUNDAY WITH AREA QUICKLY
ENDING UP ON ITS BACKSIDE BY MONDAY. NAM DELAYS THIS SOMEWHAT...BUT
LOOKING MORE CLOSELY...SHOWS MUCH STRONGER CENTER OF 1050MB VERSUS
OTHER MODELS SHOWING 1044MB...AND THIS IS ANOMALOUS WHEN COMPARED TO
INITIAL HI PRES STRENGTH IN NWRN CANADA. PREFER GFS/UKMET SOLUTION
HERE.
WX WILL BE QUIET OVER THE NEXT FEW DAYS...BUT EFFECTS FROM PREVIOUS
36HRS OF WINTER STORM WILL BE FELT THRU THIS PERIOD. RATHER HEFTY
SNOW PACK WAS DEPOSITED FROM W CNTRL IL/NERN MO THRU CNTRL MO WHERE
9 TO 16 INCHES EXISTED DURING MID MORNING AND LESSER AMOUNTS FURTHER
SEWD...WITH ONLY TRACE AMOUNTS IN PARTS OF SERN MO AND SRN IL.
NEEDLESS TO SAY...IN GENERAL ABSENCE OF STRONG WARM ADVECTION
PATTERNS...AREA OF DEEPEST SNOW PACK WILL ALLOW TEMPERATURES TO
FREEFALL AT NIGHT AND HOLD THEM BACK DURING THE DAY. WITH MOS NOT
QUITE FULLY REGISTERING THE SCOPE OF THE WINTER STORM YET...
OPPORTUNITIES ABOUND FOR BIG GAINS/IMPROVEMENTS ON TEMP FORECASTS
STARTING WITH TONIGHT WHERE MOS AVERAGE SHOWING UPPER TEENS/AROUND
20F FOR KUIN/KCOU...AND TEMPS ARE CURRENTLY 22F! LIGHT SWLY SFC WNDS
WILL DO LITTLE TO WARM THINGS UP TONIGHT OVER THE DEEP SNOW PACK
SINCE THIS WILL PARALLEL IT AND INSTEAD RESULT IN CAA. WENT FOR
5-10F FOR MINS FOR THIS AREA...WITH WARMER TEMPS SEWD WHERE LESSER
AMOUNTS OF SNOW PACK WILL LESSEN THE EFFECTS...EDGING TOWARDS THE
COLDEST MOS TEMPS.
CONTINUED THIS TREND FOR THE NEXT TWO NIGHTS...LESSENING THINGS A
BIT FOR EACH NIGHT...BUT WITH NEXT CANADIAN AIRMASS DUE IN BY LATE
SATURDAY NIGHT ANYWAY...TEMPS WILL CONTINUE TO FALL INTO THE SINGLE
DIGITS FOR THE DEEP SNOW PACK AREAS.
ALSO SEE CHANCE FOR LARGE IMPROVEMENT TO MAX TEMPS...ESPECIALLY ON
SATURDAY WHERE MOS HAS 40S FOR MANY AREAS. HAVE TRIMMED TO 30S
INSTEAD...ESPECIALLY CONSIDERING THE VERY LOW READINGS EARLY IN THE
DAY. TEMPERED THESE ADJUSTMENTS HEADING OUT IN TIME FOR SUNDAY AND
MONDAY.
FOR THE EXTENDED PERIOD (MONDAY NIGHT - FRIDAY)...NWP MODELS ARE IN
REASONABLE AGREEMENT ON AMPLIFIED H500 PATTERN DURING THIS PERIOD...
WITH LONGWAVE TROF OVER ERN NOAM AND RIDGE OVER WRN NOAM RESULTING
IN NWLY FLOW FOR THE MID MS VALLEY. IN ADDITION...MODELS SHOW RATHER
STRONG SHORTWAVE DIGGING THRU THE CNTRL CONUS DURING MID WEEK BUT
DISAGREE AS TO ITS INTENSITY AND TIMING. THE 12Z GFS HAS TRENDED FOR
A TIMING OF THURSDAY BUT ALSO SHOWING A WEAKER...MORE OPEN WAVE...
THAN IT WAS SHOWING FROM THE 00Z/06Z RUNS. THIS SEEMS TO BE MORE IN
LINE WITH THE ECMWF AND UKMET. AT THE SURFACE...ONE COLD HI PRES TO
EXIT EARLY IN THE PERIOD...BEFORE ANOTHER STRONG COLD FRONT MOVES
THRU DURING TUESDAY/WEDNESDAY TIMEFRAME...WITH THE BUILDING COLD HI
PRES DOMINATING THE AREA FOR LATE WEEK. MAIN BONE OF CONTENTION IS
WITH THE TIMING...AS GFS IS ABOUT 12HRS FASTER THAN ECMWF AND NEARLY
24HRS FASTER THAN THE UKMET. GIVEN ECMWF HAS A BETTER VERIFICATION
HISTORY OUT IN THE MEDIUM RANGE THAN THE GFS...PREFER TO ADJUST THE
GFS PER A SLOWER ARRIVAL OF CDFNT. OVERALL AM EXPECTING A DRY
FORECAST DURING THIS PERIOD AS MOISTURE WILL BE IN LIMITED SUPPLY AS
THE FA SIMPLY EXCHANGES ONE COLD DRY AIRMASS FOR ANOTHER. STRONG
SHORTWAVE FOR MID-LATE WEEK MAY DELIVER A LOW POTENTIAL FOR
PCPN...BUT UNCERTAINTY ON ITS TRACK AND FACT THAT COLD HI PRES AT
THE LO LEVELS WILL BE UNDERCUTTING IT...DOES NOT BODE WELL FOR PCPN
CHANCES. HAVE LEFT DRY FOR NOW. TEMPERATURES TO BE BELOW NORMAL
THROUGH THE PERIOD.
TES
&&
.AVIATION...
FOR THE 06Z TAFS...MUCH MORE TRANQUIL WX THIS FCST PD. SFC RDG
EXTDG FM ERN OK E THRU WRN TN WL MOV EWD. W-SWLY SFC WNDS CAN BE
EXPECTED LT TGT AND SAT MRNG ACRS THE CWA JUST N OF THE SFC RDG. A
DRY CDFNT WILL BE PUSHING SEWD THRU UIN AND COU SAT AFTN AND THE
STL METRO AREA EARLY SAT EVNG WITH THE SWLY SFC WNDS VEERING ARND
TO THE NW BHND THE CDFNT. MID LVL CLOUDINESS CURRENTLY ACRS ERN KS
AND WRN MO WILL BE MOVG EWD THRU THE CWA LT TGT AND SAT AS MDLS
DEPICT INCRSG RH BTWN 700-400 MB AFT 06Z SAT. WILL INCLUDE SCT-
BKN120 FOR SKY CONDITION IN THE TAFS MAINLY ON SAT.
GKS
&&
.LSX WATCHES/WARNINGS/ADVISORIES...
MO...NONE.
IL...NONE.
&&
$$
WFO LSX
FXUS63 KLSX 021051
AFDLSX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE ST LOUIS MO
451 AM CST SAT DEC 2 2006
.DISCUSSION...
MAIN FCST CONCERN DURING THE SHORT TERM PD IS TRYING TO DETERMINE
HOW RESIDUAL SNOW FIELD WL BE AFFECTING TEMP TRENDS ACR THE CWA.
SYNOPTICALLY...00Z SHORT TERM MODELS RMN IN FAIRLY GD AGREEMENT
WITH EACH OTHER AND WITH PREVIOUS RUNS AS UA PTRN REMAINS FAIRLY
ACTIVE. SHTWV DROPPING INTO N PLAINS TDA WL BE DEEPNENING TROF OVR
CNTRL U.S. ON SUN...BUT TROF THEN PUSHES INTO E COAST PRODUCING A
W-NW FLO REGIME OVR REGION MON-TUE. THESE TRENDS WL ALLOW WRM AIR
TO BRIEFLY SURGE INTO AREA THIS MRNG AND ERY AFTN IN ADV OF
SHTWV...WITH A CHILLY REINFORCING SHOT OF COLD AIR BHND SYS
PUSHING INTO N AREAS LT THIS AFTN...AND OVR RMNDR OF AREA TNGT.
OBVIOUSLY...DEEP SNOW FIELD OF 12+ INCHES FROM AROUND
KCOU TO NR KUIN WL BE MAKING A HUGE IMPACT ON TEMPS OVR THE NXT
FEW DAYS. EVEN THO AMS WL WRM TDA...OVR THE SNOW COVERED AREAS
TEMPS WL PROBABALY STRUGGLE TO WRM MUCH ABV 30 OR SO. AREAS EAST
OF THE SNOW FIELD...RUFLY E OF A KVIH...KSTL...KTAZ LN...SHUD PUSH
INTO THE UPR 30S AND LWR 40S.
AMS PUSHING INTO AREA ON SUN PROGGED TO BE ROUGHLY 10 DEGREES
COOLER AT 85H THAN TEMPS THIS AFTN. THIS SHUD DROP AFT HIGHS BACK
INTO THE LWR 20S OVR THE SNOW FIELD...WITH LM30S OVR SNOW FREE
AREAS IN SE PART OF FA.
SNOW COVER PRESENTS EVEN MORE OF A PROBLEM FOR OVRNIGHT LOWS THE
NXT FEW NIGHTS. ANY MIXING AND/OR CLD COVER WL HOLD TEMPS UP...BUT IF
CLR SKIES AND LGT WNDS TAKE HOLD THE MERCURY WL DROP LIKE A ROCK.
THIS CAN BE SEEN AT 10Z THIS MRNG...WITH CLDS HOLD TEMP AT KCOU AT
16...WHILE CLR SKIES AT KAIZ HAS ALLOW TEP TO DROP TO 7. MODELS DO
HINT AT A BIT OF MID LVL MSTR OVR S AREAS TNGT...ALG WITH SM
MIXING THRUOUT REGION BHND CDFNT. DECIDED TO STAY FAIRLY CLOSE TO
GOING TRENDS...ALLOWING MINS FOR SUN MRNG TO DIP INTO THE SINGLE
DIGITS OVR THE SNOW FIELD...WITH TEENS AND LWR 20S SE MO/S IL.
WENT A FEW DEGREES COLDER MOST AREAS ON MON MRNG WITH MODEL RH
FIELDS SUGGESTING FEWER CLDS...BUT WITH A BIT OF MIXING AS RETURN
FLOW STRUGGLES TO DVLP ON BACK SIDE OF SFC RDG.
A QUICK CHECK OF THE RECORD BOOKS AT KCOU AND KUIN INDICATE THAT
WE ARE ENTERING THAT TIME OF YEAR WHERE THE RECORD MINS FOR THESE
STATIONS BGN TO HEAD TWD ZERO. CANT TOTALLY RULE OUT THE CHCS OF
HITTING A RECORD...BUT CONDITIONS WOULD HAVE TO BE PERFECT FOR
THIS TO OCR...AND CURRENTLY IT WOULD APR THAT WE'LL HAVE A BIT TOO
MUCH CLOUDINESS AND/OR MIXING THE NXT FEW NIGHTS TO REACH THESE LEVELS.
TEMPS SHUD MODERATE SOME ON MON AND TUE AS FLOW REGIME KEEPS
COLDEST AIR LOCKED TO OUR N. SNOW FIELD WL CONT TO IMPACT
TEMPS...BUT EFFECTS SHUD BE LESSENING WITH TIME AS SNOW BGNS TO
MELT AND EDGES OF THE SNOW FIELD BGN TO ERODE AND SHRINK.
TRUETT
&&
.AVIATION...
FOR THE 06Z TAFS...MUCH MORE TRANQUIL WX THIS FCST PD. SFC RDG
EXTDG FM ERN OK E THRU WRN TN WL MOV EWD. W-SWLY SFC WNDS CAN BE
EXPECTED LT TGT AND SAT MRNG ACRS THE CWA JUST N OF THE SFC RDG. A
DRY CDFNT WILL BE PUSHING SEWD THRU UIN AND COU SAT AFTN AND THE
STL METRO AREA EARLY SAT EVNG WITH THE SWLY SFC WNDS VEERING ARND
TO THE NW BHND THE CDFNT. MID LVL CLOUDINESS CURRENTLY ACRS ERN KS
AND WRN MO WILL BE MOVG EWD THRU THE CWA LT TGT AND SAT AS MDLS
DEPICT INCRSG RH BTWN 700-400 MB AFT 06Z SAT. WILL INCLUDE SCT-
BKN120 FOR SKY CONDITION IN THE TAFS MAINLY ON SAT.
GKS
&&
.CLIMATE...
RECORD LOWS FOR THE NXT FEW NIGHTS...
KCOU
KUIN
12/3 0 IN 1895
1 IN 1929
12/4 2 IN 1893
3 IN 1991
12/5 -4 IN 1895
7 IN 1964
&&
.LSX WATCHES/WARNINGS/ADVISORIES...
MO...NONE.
IL...NONE.
&&
$$
WFO LSX
FXUS63 KLSX 021119
AFDLSX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE ST LOUIS MO
519 AM CST SAT DEC 2 2006
.DISCUSSION...
MAIN FCST CONCERN DURING THE SHORT TERM PD IS TRYING TO DETERMINE
HOW RESIDUAL SNOW FIELD WL BE AFFECTING TEMP TRENDS ACR THE CWA.
SYNOPTICALLY...00Z SHORT TERM MODELS RMN IN FAIRLY GD AGREEMENT
WITH EACH OTHER AND WITH PREVIOUS RUNS AS UA PTRN REMAINS FAIRLY
ACTIVE. SHTWV DROPPING INTO N PLAINS TDA WL BE DEEPNENING TROF OVR
CNTRL U.S. ON SUN...BUT TROF THEN PUSHES INTO E COAST PRODUCING A
W-NW FLO REGIME OVR REGION MON-TUE. THESE TRENDS WL ALLOW WRM AIR
TO BRIEFLY SURGE INTO AREA THIS MRNG AND ERY AFTN IN ADV OF
SHTWV...WITH A CHILLY REINFORCING SHOT OF COLD AIR BHND SYS
PUSHING INTO N AREAS LT THIS AFTN...AND OVR RMNDR OF AREA TNGT.
OBVIOUSLY...DEEP SNOW FIELD OF 12+ INCHES FROM AROUND
KCOU TO NR KUIN WL BE MAKING A HUGE IMPACT ON TEMPS OVR THE NXT
FEW DAYS. EVEN THO AMS WL WRM TDA...OVR THE SNOW COVERED AREAS
TEMPS WL PROBABALY STRUGGLE TO WRM MUCH ABV 30 OR SO. AREAS EAST
OF THE SNOW FIELD...RUFLY E OF A KVIH...KSTL...KTAZ LN...SHUD PUSH
INTO THE UPR 30S AND LWR 40S.
AMS PUSHING INTO AREA ON SUN PROGGED TO BE ROUGHLY 10 DEGREES
COOLER AT 85H THAN TEMPS THIS AFTN. THIS SHUD DROP AFT HIGHS BACK
INTO THE LWR 20S OVR THE SNOW FIELD...WITH LM30S OVR SNOW FREE
AREAS IN SE PART OF FA.
SNOW COVER PRESENTS EVEN MORE OF A PROBLEM FOR OVRNIGHT LOWS THE
NXT FEW NIGHTS. ANY MIXING AND/OR CLD COVER WL HOLD TEMPS UP...BUT IF
CLR SKIES AND LGT WNDS TAKE HOLD THE MERCURY WL DROP LIKE A ROCK.
THIS CAN BE SEEN AT 10Z THIS MRNG...WITH CLDS HOLD TEMP AT KCOU AT
16...WHILE CLR SKIES AT KAIZ HAS ALLOW TEP TO DROP TO 7. MODELS DO
HINT AT A BIT OF MID LVL MSTR OVR S AREAS TNGT...ALG WITH SM
MIXING THRUOUT REGION BHND CDFNT. DECIDED TO STAY FAIRLY CLOSE TO
GOING TRENDS...ALLOWING MINS FOR SUN MRNG TO DIP INTO THE SINGLE
DIGITS OVR THE SNOW FIELD...WITH TEENS AND LWR 20S SE MO/S IL.
WENT A FEW DEGREES COLDER MOST AREAS ON MON MRNG WITH MODEL RH
FIELDS SUGGESTING FEWER CLDS...BUT WITH A BIT OF MIXING AS RETURN
FLOW STRUGGLES TO DVLP ON BACK SIDE OF SFC RDG.
A QUICK CHECK OF THE RECORD BOOKS AT KCOU AND KUIN INDICATE THAT
WE ARE ENTERING THAT TIME OF YEAR WHERE THE RECORD MINS FOR THESE
STATIONS BGN TO HEAD TWD ZERO. CANT TOTALLY RULE OUT THE CHCS OF
HITTING A RECORD...BUT CONDITIONS WOULD HAVE TO BE PERFECT FOR
THIS TO OCR...AND CURRENTLY IT WOULD APR THAT WE'LL HAVE A BIT TOO
MUCH CLOUDINESS AND/OR MIXING THE NXT FEW NIGHTS TO REACH THESE LEVELS.
TEMPS SHUD MODERATE SOME ON MON AND TUE AS FLOW REGIME KEEPS
COLDEST AIR LOCKED TO OUR N. SNOW FIELD WL CONT TO IMPACT
TEMPS...BUT EFFECTS SHUD BE LESSENING WITH TIME AS SNOW BGNS TO
MELT AND EDGES OF THE SNOW FIELD BGN TO ERODE AND SHRINK.
TRUETT
&&
.AVIATION...
FOR THE 12Z TAFS...
SEEING SOME MOISTURE CREEP INTO THE CWFA FROM THE WEST AT AROUND
12,000 FT...BUT OTHER THAN THAT NO SIGNIFICANT CLOUDINESS TO
REPORT THIS MORNING. THOUGH THERE'S BEEN NO REPORTS OF FOG THIS
MORNING...IT STILL SEEMS LIKELY THAT THERE'S SOME FOG IN LOW-LYING
AREAS THIS MORNING WHERE THERE'S SNOW/ICE COVER...BUT HAVE LEFT ANY
MENTION OF FOG OUT OF THE TERMINALS THIS MORNING DUE TO LACK OF REPORTS.
LIGHT SOUTHWEST FLOW TODAY AHEAD OF A REINFORCING COLD FRONT WHICH
WILL MOVE IN FROM THE NORTHWEST THIS EVENING. WILL SEE FLOW ACROSS
THE AREA TURN BACK TO THE NORTHWEST AS THE FRONT PASSES AFTER 00Z.
CARNEY
&&
.CLIMATE...
RECORD LOWS FOR THE NXT FEW NIGHTS...
KCOU
KUIN
12/3 0 IN 1895
1 IN 1929
12/4 2 IN 1893
3 IN 1991
12/5 -4 IN 1895
7 IN 1964
&&
.LSX WATCHES/WARNINGS/ADVISORIES...
MO...NONE.
IL...NONE.
&&
$$
WFO LSX
FXUS63 KLSX 022115
AFDLSX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE ST LOUIS MO
315 PM CST SAT DEC 2 2006
.DISCUSSION...
BROAD LONG WAVE TROF WILL BECOME ESTABLISHED OVER THE EASTERN U.S.
OVER THE NEXT 48H AS A SERIES OF SHRTWV TROFS IN THE NORTHERN AND
SOUTHERN STREAMS PROGRESS EASTWARD. SOUTHERN TROF MOVING THROUGH
THE SRN ROCKIES ATTM WILL PRODUCE MID/HI CLOUDS ACROSS MAINLY SRN
MO AND SRN IL OVR THE NEXT 18-24H. MEANWHILE THE NRN STREAM TROF
OVR THE NCNTRL PLAINS ATTM IS RESPONSIBLE FOR A REINFORCING CDFNT
NOW MOVING THRU THE NW PORTION OF THE CWA. THIS CDFNT WILL CONTINUE
TO MOVE THRU THE REGION THIS EVENING WITH GOOD CAA IN ITS WAKE AND
HI PRES BUILDING SEWD FROM THE NRN PLAINS INTO THE LOWER MS VLY
ON SUNDAY. THE MODELS ARE A LITTLE BIT AT ODDS AFTER THIS PERIOD
FROM MONDAY NIGHT INTO EARLY TUESDAY...WHEN THE GFS SUGGESTS
ANOTHER CDFNT WILL HAVING A GLANCING BLOW ON THE AREA BRIEFLY
MAINTAINING COLDER AIR. ALTERNATIVELY THE WRF-NAM AND UKMET
INDICATE PROMINENT LOW LEVEL WAA BECOMING ESTABLISHED UNTIL THE
NEXT DECIDED COLD FROPA OCCURRING AROUND MIDWEEK. ATTM WE HAVE
FAVORED THE MODERATING CONSENUS SOLUTION OF THE NAM AND UKMET.
WITH THESE ALTERNATING PATTERNS OF LOW LEVEL WAA AND CAA AND THE
EXISTING SNOW AND ICE COVER...TEMPERATURES WILL BE QUITE A CHALLENGE.
FORTUNATELY THIS SHOULD BE THE ONLY PROBLEM AS THE PATTERN LARGELY APPEARS
TO BE A DRY ONE. TEMPERATURES TODAY ACTUALLY REBOUNDED RELATIVELY
WELL OVER THE SNOW/ICE COVER AFTER MINS IN THE SINGLE DIGITS...WITH
MID AFTERNOON READINGS IN THE LOW-MID 30S. OUTIDE OF THIS...TEMPS
CLIMBED INTO THE 40S WITH A RAWS SITE IN SE REYNOLDS COUNTY IN THE
U40S. HAVE USED TODAYS READINGS TO LARGELY GUIDE HIGHS OVER THE
NEXT FEW DAYS. LOWS SHOULD CONTINUE TO BE QUITE COLD OVER THE SNOW
WITH READINGS TONIGHT AND SUNDAY NIGHT IN THE SINGLE DIGITS. AFTER
THIS TIME TEMPS WILL CONTINUE TO BE SUPRESSED BY SNOW COVER...BUT IT
WILL BE SHRINKING AND GET OLDER WITH LESSER INFLUENCE AS TIME PROGRESSES.
SUNDAY WILL BE QUITE COLD ACROSS THE ENTIRE CWA WITH THE SNOW FIELD
AND THEN NWLY WINDS ADVECTING THE ALREADY COLD AIR OFF THE SNOW
FIELD. ON MONDAY AND TUESDAY THE SFC WINDS WILL BE MORE SWLY
ALLOWING THOSE AREAS OUTSIDE OF THE SNOW/ICE TO WARM SEASONABLY.
THE SWLY WINDS AND WAA PATTERN SHOULD START THE PROCESS OF REDUCING
THE SNOW COVER...HOWEVER THERE WILL STILL BE A LONG FETCH OF AIR
OVER SNOW FROM CENTRAL MO INTO WCNTRL IL...KEEPING TEMPS SUPPRESSED.
MODEL MOS GUIDANCE WAS GENERALLY NOT USED OVER THE NEXT FEW DAYS
OVER THE SNOW REGIONS.
GLASS
&&
.AVIATION...
FOR THE 12Z TAFS...
SEEING SOME MOISTURE CREEP INTO THE CWFA FROM THE WEST AT AROUND
12,000 FT...BUT OTHER THAN THAT NO SIGNIFICANT CLOUDINESS TO
REPORT THIS MORNING. THOUGH THERE'S BEEN NO REPORTS OF FOG THIS
MORNING...IT STILL SEEMS LIKELY THAT THERE'S SOME FOG IN LOW-LYING
AREAS THIS MORNING WHERE THERE'S SNOW/ICE COVER...BUT HAVE LEFT ANY
MENTION OF FOG OUT OF THE TERMINALS THIS MORNING DUE TO LACK OF REPORTS.
LIGHT SOUTHWEST FLOW TODAY AHEAD OF A REINFORCING COLD FRONT WHICH
WILL MOVE IN FROM THE NORTHWEST THIS EVENING. WILL SEE FLOW ACROSS
THE AREA TURN BACK TO THE NORTHWEST AS THE FRONT PASSES AFTER 00Z.
CARNEY
&&
.CLIMATE...
RECORD LOWS FOR THE NXT FEW NIGHTS...
KCOU
KUIN
12/3 0 IN 1895
1 IN 1929
12/4 2 IN 1893
3 IN 1991
12/5 -4 IN 1895
7 IN 1964
&&
.LSX WATCHES/WARNINGS/ADVISORIES...
MO...NONE.
IL...NONE.
&&
$$
WFO LSX
FXUS63 KLSX 022355
AFDLSX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE ST LOUIS MO
555 PM CST SAT DEC 2 2006
.DISCUSSION...
BROAD LONG WAVE TROF WILL BECOME ESTABLISHED OVER THE EASTERN U.S.
OVER THE NEXT 48H AS A SERIES OF SHRTWV TROFS IN THE NORTHERN AND
SOUTHERN STREAMS PROGRESS EASTWARD. SOUTHERN TROF MOVING THROUGH
THE SRN ROCKIES ATTM WILL PRODUCE MID/HI CLOUDS ACROSS MAINLY SRN
MO AND SRN IL OVR THE NEXT 18-24H. MEANWHILE THE NRN STREAM TROF
OVR THE NCNTRL PLAINS ATTM IS RESPONSIBLE FOR A REINFORCING CDFNT
NOW MOVING THRU THE NW PORTION OF THE CWA. THIS CDFNT WILL CONTINUE
TO MOVE THRU THE REGION THIS EVENING WITH GOOD CAA IN ITS WAKE AND
HI PRES BUILDING SEWD FROM THE NRN PLAINS INTO THE LOWER MS VLY
ON SUNDAY. THE MODELS ARE A LITTLE BIT AT ODDS AFTER THIS PERIOD
FROM MONDAY NIGHT INTO EARLY TUESDAY...WHEN THE GFS SUGGESTS
ANOTHER CDFNT WILL HAVING A GLANCING BLOW ON THE AREA BRIEFLY
MAINTAINING COLDER AIR. ALTERNATIVELY THE WRF-NAM AND UKMET
INDICATE PROMINENT LOW LEVEL WAA BECOMING ESTABLISHED UNTIL THE
NEXT DECIDED COLD FROPA OCCURRING AROUND MIDWEEK. ATTM WE HAVE
FAVORED THE MODERATING CONSENUS SOLUTION OF THE NAM AND UKMET.
WITH THESE ALTERNATING PATTERNS OF LOW LEVEL WAA AND CAA AND THE
EXISTING SNOW AND ICE COVER...TEMPERATURES WILL BE QUITE A CHALLENGE.
FORTUNATELY THIS SHOULD BE THE ONLY PROBLEM AS THE PATTERN LARGELY APPEARS
TO BE A DRY ONE. TEMPERATURES TODAY ACTUALLY REBOUNDED RELATIVELY
WELL OVER THE SNOW/ICE COVER AFTER MINS IN THE SINGLE DIGITS...WITH
MID AFTERNOON READINGS IN THE LOW-MID 30S. OUTIDE OF THIS...TEMPS
CLIMBED INTO THE 40S WITH A RAWS SITE IN SE REYNOLDS COUNTY IN THE
U40S. HAVE USED TODAYS READINGS TO LARGELY GUIDE HIGHS OVER THE
NEXT FEW DAYS. LOWS SHOULD CONTINUE TO BE QUITE COLD OVER THE SNOW
WITH READINGS TONIGHT AND SUNDAY NIGHT IN THE SINGLE DIGITS. AFTER
THIS TIME TEMPS WILL CONTINUE TO BE SUPRESSED BY SNOW COVER...BUT IT
WILL BE SHRINKING AND GET OLDER WITH LESSER INFLUENCE AS TIME PROGRESSES.
SUNDAY WILL BE QUITE COLD ACROSS THE ENTIRE CWA WITH THE SNOW FIELD
AND THEN NWLY WINDS ADVECTING THE ALREADY COLD AIR OFF THE SNOW
FIELD. ON MONDAY AND TUESDAY THE SFC WINDS WILL BE MORE SWLY
ALLOWING THOSE AREAS OUTSIDE OF THE SNOW/ICE TO WARM SEASONABLY.
THE SWLY WINDS AND WAA PATTERN SHOULD START THE PROCESS OF REDUCING
THE SNOW COVER...HOWEVER THERE WILL STILL BE A LONG FETCH OF AIR
OVER SNOW FROM CENTRAL MO INTO WCNTRL IL...KEEPING TEMPS SUPPRESSED.
MODEL MOS GUIDANCE WAS GENERALLY NOT USED OVER THE NEXT FEW DAYS
OVER THE SNOW REGIONS.
GLASS
&&
.AVIATION...
FOR THE 00Z TAFS...SEWD MOVG CDFNT HAS PASSED JUST SE OF STL AND
SUS ATTM...ALTHOUGH THE SFC WND IS STILL CALM AND THE SFC DWPTS
ARE IN THE UPR 20S. THESE CALM WNDS AND RELATIVELY HI SFC DWPTS
ALONG WITH MELTING SNOW AND ICE HAS LEAD TO SOME FOG...MAINLY
GROUND FOG IN THE STL METRO AREA. WILL MENTION FOG IN THE STL AND
SUS TAFS TIL 03Z SUN WITH PREVAILING VSBYS OF 5-6SM BR AND A TEMPO
GRP WITH VSBYS DOWN TO 3-4SM BR. LTR THIS EVNG AS THE NRN
PLAINS/RCKYS SFC RDG BUILDS SEWD THRU THE CWA THE SFC WND SHOULD
PICK UP FROM THE NW AND THE SFC DWPTS WILL FALL PLUS THE SNOW/ICE
MELT WILL CEASE SO THIS FOG SHOULD BE SHORT LIVED. MID-HI LVL
CLOUDINESS SHOULD CONT TO STREAM E-NEWD THRU THE CWA ESPECIALLY
THE SRN HALF...ALNG AND S OF INTERSTATE 70. LOOKING AT THE MDL
FCST TIME HGT SECTIONS OF RH IT APRS THAT THIS MID LVL CLOUIDNESS
WILL MOVE OUT OF THE AREA BY LT SUN MRNG AS THE RH BTWN 500-700 MB
DECREASES AFT 12Z SUN.
GKS
&&
.CLIMATE...
RECORD LOWS FOR THE NXT FEW NIGHTS...
KCOU
KUIN
12/3 0 IN 1895
1 IN 1929
12/4 2 IN 1893
3 IN 1991
12/5 -4 IN 1895
7 IN 1964
&&
.LSX WATCHES/WARNINGS/ADVISORIES...
MO...NONE.
IL...NONE.
&&
$$
WFO LSX
|