FXUS63 KILX 280917
AFDILX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE LINCOLN IL
316 AM CST TUE NOV 28 2006
.DISCUSSION...
A PROBLEMATIC FORECAST THIS ROUND. SOUTHWESTERLY FLOW CONTINUES TO
DOMINATE THE FLOW AS A MAJOR TROF DIGS IN OVER THE WEST COAST.
SATELLITE WATER VAPOR IMAGERY SHOWING RICH MOISTURE PLUME MOVING IN
FROM THE SOUTHERN PLAINS. SHOWERY PRECIP ACROSS THE NWRN PORTIONS OF
THE STATE IN THE OVERNIGHT HOURS AS EMBEDDED WAVES MOVE THROUGH THE
SWRLY FLOW ALONG A STATIONARY FRONTAL BOUNDARY. MODELS STILL NOT
SHOWING A LOT OF CONSISTENCY WITH THE HANDLING OF THE MAIN WEATHER
MAKER COMING THROUGH WITH THE FRONT WED/THU/FRI. STILL MAINTAINING A
SLOWING TREND...NOW NOT PUSHING THE FRONT ALL THE WAY THRU THE CWA
UNTIL AFTER 12Z THU. AS FAR AS A MODEL CHOICE...CHOOSING ONE MODEL
IS IMPRACTICAL AT BEST.  MOST CONSISTENT MODEL IS THE CAN GEM...BUT
IS ALSO A BIT OF A CONSERVATIVE OUTLIER.  THE NAM/WRF IS ALSO A BIT
OFF OF THE TREND OF THE OTHER THREE...MOVING THE LOW THROUGH MUCH
FASTER (BY 6-12 HOURS) AND FURTHER TO THE NORTH AND EAST.  LATEST
(00Z) ECMWF IS ACTUALLY PUSHING THE SFC LOW FURTHER TO THE SOUTH
THAN THE GFS...BUT LIKE EVERYTHING ELSE WITH THIS FORECAST...AM
LOOKING FOR MORE THAN ONE SIGNAL BEFORE COMMITTING TO IT.  AS A
RESULT...WILL BLEND THE GFS AND THE ECMWF. ALL IN ALL...A WINTRY
MIXED BAG OF PRECIP IS BEING POINTED TO IN SEVERAL MODELS FOR AT
LEAST AREAS NORTH AND WEST OF THE ILLINOIS RIVER VALLEY
THURSDAY/THURSDAY NIGHT.
SHORT TERM...TODAY AND TOMORROW...
KEEPING THE POPS IN FOR MUCH OF THE CWA TODAY AS THE EMBEDDED WAVE
ARE NOW HELPING TO SPAWN PRECIP AS FAR SE AS LAWRENCEVILLE.
HOWEVER...MORE OF A LOW POP IS FINE FOR COVERAGE ISSUES AT THIS
POINT WITH THE MORE AGGRESSIVE LIFT STILL OFF TO THE NORTHWEST. WED
GOING TO BE AWFULLY WARM FOR LATE NOVEMBER...WITH SOUTHERLY FLOW AT
THE SFC USHERING IN SOME WARM MUGGY AIR IN ADVANCE OF A COLD FRONT.
COLD FRONT WILL BRING CHANCE FOR THUNDER ON WED...MOVING FROM NW TO
SE WITH THE FRONT. FRONT WILL NOT MAKE IT ALL THE WAY THROUGH ON
WED...AND CHANCES FOR RAIN AND THUNDER WILL CONTINUE IN THE
OVERNIGHT HOURS.
LONG TERM...THURSDAY THROUGH MONDAY...
WITH MODELS CONTINUING TO SLOW THE FROPA...SERN COUNTIES WILL
CONTINUE TO SEE GOOD CHANCES FOR PRECIP THROUGH THE EARLY MORNING
HOURS ON THURSDAY.  H5 TROF AND SFC LOW HANGING BACK A BIT UNTIL
THURSDAY/THU NIGHT AS IT MOVES IN.  WILL SEE A SWITCH TO WINTER
PRECIP AS THURSDAY PROGRESSES AND THE COLDER AIR EDGES IN FROM THE
NW.  DEVELOPING SFC LOW IS MODELED TO RIDE UP THE COLD FRONT AT THE
SFC.  THURSDAY NIGHT...THE H5 TROF MOVES OVER THE REGION...INTO A
NEGATIVE TILT.  IN RESPONSE...THE SFC CYCLONE DEEPENS
RAPIDLY...PUTTING THE FA ON THE BACKSIDE OF THE SFC LOW. THE BIG
QUESTION AT THIS POINT IS THE ACTUAL TRACK OF THIS LOW...AND WHEN IT
ACTUALLY DEEPENS/BECOMES NEGATIVELY TILTED.  EACH FORECAST RUN WITH
THE GFS HAS BEEN BACKING THE SYSTEM UP TO THE WEST...BUT THE LAST
ECMWF IS DROPPING THE LOW TO THE SOUTH.  WHEREAS IF THE GFS/ECMWF
VERIFIES...WINDY CONDITIONS IN A RAPIDLY INCREASING PRESSURE
GRADIENT COULD ACCOMPANY A RATHER SIGNIFICANT SNOW EVENT FOR THE
WESTERN PORTIONS OF THE CWA (AND CONSIDERABLY LESS WINTER PRECIP ON
THE ERN SIDE OF THE STATE)... ALL OF THIS IS DEPENDENT ON A LOT OF
CHALLENGING FACTORS.  WITHOUT A LOT OF CONFIDENCE IN THE WIDE RANGE
OF MODEL SOLNS...WILL REMAIN SKEPTICAL.
REMAINING FORECAST DRY AT THIS POINT...THOUGH BEGINNING TO SHOW A
SIGNAL OF POSSIBLE PRECIP FOR THE NRN TIER OF ILLINOIS LATE IN THE
WEEKEND AS ANOTHER UPPER LEVEL TROF MOVES THROUGH...WITH A
REINFORCING ALBEIT BRIEF SHOT OF COLD AIR.
&&
.ILX WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
HJS

FXUS63 KILX 281639
AFDILX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE LINCOLN IL
1035 AM CST TUE NOV 28 2006
.DISCUSSION...
SHORT-WAVE EMBEDDED IN BROAD SOUTHWESTERLY FLOW PATTERN IS CURRENTLY
RESPONSIBLE FOR SCATTERED SHOWERS/STORMS ACROSS IOWA AND
MISSOURI...WHILE THE PRECIP IS MUCH MORE ISOLATED IN NATURE ACROSS
CENTRAL ILLINOIS.  WITH WAVE PASSING BY JUST W/NW OF THE
AREA...THINK SCT SHOWERS WILL CONTINUE THROUGH MUCH OF THE
AFTERNOON.  ONCE WAVE LIFTS TOWARD THE GREAT LAKES...A BREAK IN THE
PRECIP IS LIKELY TONIGHT INTO EARLY WEDNESDAY.  TEMP-WISE...16Z
READINGS ARE IN THE UPPER 50S TO AROUND 60 DEGREES...WELL ON THEIR
WAY TO AFTERNOON HIGHS IN THE MIDDLE TO UPPER 60S.  HAVE MADE A FEW
MINOR TWEAKS TO TEMP AND WIND GRIDS.
&&
.PREV DISCUSSION...
A PROBLEMATIC FORECAST THIS ROUND. SOUTHWESTERLY FLOW CONTINUES TO
DOMINATE THE FLOW AS A MAJOR TROF DIGS IN OVER THE WEST COAST.
SATELLITE WATER VAPOR IMAGERY SHOWING RICH MOISTURE PLUME MOVING IN
FROM THE SOUTHERN PLAINS. SHOWERY PRECIP ACROSS THE NWRN PORTIONS OF
THE STATE IN THE OVERNIGHT HOURS AS EMBEDDED WAVES MOVE THROUGH THE
SWRLY FLOW ALONG A STATIONARY FRONTAL BOUNDARY. MODELS STILL NOT
SHOWING A LOT OF CONSISTENCY WITH THE HANDLING OF THE MAIN WEATHER
MAKER COMING THROUGH WITH THE FRONT WED/THU/FRI. STILL MAINTAINING A
SLOWING TREND...NOW NOT PUSHING THE FRONT ALL THE WAY THRU THE CWA
UNTIL AFTER 12Z THU. AS FAR AS A MODEL CHOICE...CHOOSING ONE MODEL
IS IMPRACTICAL AT BEST.  MOST CONSISTENT MODEL IS THE CAN GEM...BUT
IS ALSO A BIT OF A CONSERVATIVE OUTLIER.  THE NAM/WRF IS ALSO A BIT
OFF OF THE TREND OF THE OTHER THREE...MOVING THE LOW THROUGH MUCH
FASTER (BY 6-12 HOURS) AND FURTHER TO THE NORTH AND EAST.  LATEST
(00Z) ECMWF IS ACTUALLY PUSHING THE SFC LOW FURTHER TO THE SOUTH
THAN THE GFS...BUT LIKE EVERYTHING ELSE WITH THIS FORECAST...AM
LOOKING FOR MORE THAN ONE SIGNAL BEFORE COMMITTING TO IT.  AS A
RESULT...WILL BLEND THE GFS AND THE ECMWF. ALL IN ALL...A WINTRY
MIXED BAG OF PRECIP IS BEING POINTED TO IN SEVERAL MODELS FOR AT
LEAST AREAS NORTH AND WEST OF THE ILLINOIS RIVER VALLEY
THURSDAY/THURSDAY NIGHT.
SHORT TERM...TODAY AND TOMORROW...
KEEPING THE POPS IN FOR MUCH OF THE CWA TODAY AS THE EMBEDDED WAVE
ARE NOW HELPING TO SPAWN PRECIP AS FAR SE AS LAWRENCEVILLE.
HOWEVER...MORE OF A LOW POP IS FINE FOR COVERAGE ISSUES AT THIS
POINT WITH THE MORE AGGRESSIVE LIFT STILL OFF TO THE NORTHWEST. WED
GOING TO BE AWFULLY WARM FOR LATE NOVEMBER...WITH SOUTHERLY FLOW AT
THE SFC USHERING IN SOME WARM MUGGY AIR IN ADVANCE OF A COLD FRONT.
COLD FRONT WILL BRING CHANCE FOR THUNDER ON WED...MOVING FROM NW TO
SE WITH THE FRONT. FRONT WILL NOT MAKE IT ALL THE WAY THROUGH ON
WED...AND CHANCES FOR RAIN AND THUNDER WILL CONTINUE IN THE
OVERNIGHT HOURS.
LONG TERM...THURSDAY THROUGH MONDAY...
WITH MODELS CONTINUING TO SLOW THE FROPA...SERN COUNTIES WILL
CONTINUE TO SEE GOOD CHANCES FOR PRECIP THROUGH THE EARLY MORNING
HOURS ON THURSDAY.  H5 TROF AND SFC LOW HANGING BACK A BIT UNTIL
THURSDAY/THU NIGHT AS IT MOVES IN.  WILL SEE A SWITCH TO WINTER
PRECIP AS THURSDAY PROGRESSES AND THE COLDER AIR EDGES IN FROM THE
NW.  DEVELOPING SFC LOW IS MODELED TO RIDE UP THE COLD FRONT AT THE
SFC.  THURSDAY NIGHT...THE H5 TROF MOVES OVER THE REGION...INTO A
NEGATIVE TILT.  IN RESPONSE...THE SFC CYCLONE DEEPENS
RAPIDLY...PUTTING THE FA ON THE BACKSIDE OF THE SFC LOW. THE BIG
QUESTION AT THIS POINT IS THE ACTUAL TRACK OF THIS LOW...AND WHEN IT
ACTUALLY DEEPENS/BECOMES NEGATIVELY TILTED.  EACH FORECAST RUN WITH
THE GFS HAS BEEN BACKING THE SYSTEM UP TO THE WEST...BUT THE LAST
ECMWF IS DROPPING THE LOW TO THE SOUTH.  WHEREAS IF THE GFS/ECMWF
VERIFIES...WINDY CONDITIONS IN A RAPIDLY INCREASING PRESSURE
GRADIENT COULD ACCOMPANY A RATHER SIGNIFICANT SNOW EVENT FOR THE
WESTERN PORTIONS OF THE CWA (AND CONSIDERABLY LESS WINTER PRECIP ON
THE ERN SIDE OF THE STATE)... ALL OF THIS IS DEPENDENT ON A LOT OF
CHALLENGING FACTORS.  WITHOUT A LOT OF CONFIDENCE IN THE WIDE RANGE
OF MODEL SOLNS...WILL REMAIN SKEPTICAL.
REMAINING FORECAST DRY AT THIS POINT...THOUGH BEGINNING TO SHOW A
SIGNAL OF POSSIBLE PRECIP FOR THE NRN TIER OF ILLINOIS LATE IN THE
WEEKEND AS ANOTHER UPPER LEVEL TROF MOVES THROUGH...WITH A
REINFORCING ALBEIT BRIEF SHOT OF COLD AIR.
&&
.ILX WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
BARNES/HJS

FXUS63 KILX 282058
AFDILX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE LINCOLN IL
258 PM CST TUE NOV 28 2006
.DISCUSSION...
INTERESTING AND COMPLEX WEATHER SCENARIO TO UNFOLD OVER CENTRAL IL
OVER THE NEXT 48+ HOURS AS WE TRANSITION FROM MID-FALL TO MID-WINTER
CONDITIONS.  OBVIOUS FORECAST CHALLENGE IS POTENT MID TO LATE WEEK
STORM SYSTEM WHICH LOOKS TO PROVIDE PLENTY OF PRECIP...BOTH IN
LIQUID AND FROZEN STATES.  SHARP COOLOFF FROM UNSEASONABLY WARM
CONDITIONS FOR LAST WEEK OR SO...TO UNSEASONABLY COLD BY END OF THE
WEEK WITH PASSAGE OF STRONG COLD FRONT.  MAJOR SHIFT IN MOST FORECAST
MODELS LAST 12 HOURS...TRENDING TO A MORE PROGRESSIVE AND WEAKER
/FARTHER SE/ THURSDAY SYSTEM...SIGNIFICANTLY IMPACTING FROZEN PRECIP
LOCATION AND AMOUNTS.
EARLY AFTERNOON SURFACE ANALYSIS SHOWING WEAKLY ORGANIZED LOW
PRESSURE OVER MN...WITH A COLD FRONT EXTENDING SOUTHWARD INTO
NERN KS.  AHEAD OF THIS SYSTEM...DEEP AND STRONG SOUTHERLY FLOW
TRANSPORTING 55-65F DEWPOINTS UP FROM EAST TX INTO WI.  DEEP TROUGH
EVIDENT ON WV IMAGERY OVER THE INTERMOUNTAIN WEST...WITH SEVERAL
WEAK SHORTWAVES RIPPLING OUT AHEAD OF THIS FEATURE IN BROAD AND
DIFLUENT UPPER LEVEL FLOW.  WAA/ISENTROPIC LIFT IN COMBINATION WITH
SHORTWAVES HELPING TO FIRE SOME LATE NOVEMBER CONVECTION OVER THE
UPPER MIDWEST EARLIER TODAY.  ANOTHER UNSEASONABLY WARM DAY
LOCALLY...WITH TEMPS STAYING A FEW DEGREES BELOW RECORD HIGHS
DESPITE PLENTY OF CLOUD COVER.
SHORT TERM...TONIGHT THROUGH FRIDAY...
SOUTHERLY FLOW AHEAD OF COLD FRONT AND PLENTY OF MID/LOW LEVEL
CLOUD COVER TO KEEP TEMPERATURES UNSEASONABLY WARM AGAIN
TONIGHT...APPROACHING RECORD WARM LOWS AT PIA /56/ AND LINCOLN /55/.
CANNOT RULE OUT SOME ISOLATED SHOWERS OVERNIGHT IN BROAD WAA REGIME
WITH THE HELP OF ANY SUBTLE SHORTWAVES SO HAVE INCLUDED A 30 POP
OVERNIGHT.  RAIN CHANCES INCREASE BY DAYBREAK ALONG AND NW OF THE IL
RIVER AS STRONG COLD FRONT APPROACHES...AND CONTINUE TO INCREASE TO
THE SE THROUGH THE AFTERNOON.  ANOTHER VERY WARM LATE NOVEMBER DAY
ON TAP AS FRONT ONLY BISECTS CWA BY LATE AFTERNOON.  EXTENT OF DEEP
MOISTURE INFLUX AND MID LEVEL LAPSE RATES MAKE THUNDER A GOOD BET
WITH ELEVATED CAPES AOA 500 J/KG DURING THE AFTERNOON. NOTED SPC
SLGT RISK ENCROACHING ON WESTERN CWA...WILL HAVE SOME GOOD SPEED
SHEAR TO WORK WITH SO COULD SEE A FEW REPORTS OF GUSTY WINDS WITH
THE STRONGEST STORMS.  RAIN WITH EMBEDDED THUNDERSTORMS TO CONTINUE
OVERNIGHT AS STRONG SYNOPTIC SCALE LIFT ENHANCES PRECIP BEHIND COLD
FRONT.
REAL FUN AND HEADACHES BEGIN EARLY THURSDAY MORNING AS BL TEMPS BEGIN
TO COOL BELOW FREEZING NEAR GBG AS SHALLOW ARCTIC AIR...LAGGING MAIN
FRONT...MAKES IT/S MOVE.  NOT A CLASSIC FREEZING RAIN SETUP...OR
CLIMATOLOGICALLY FAVORED...BUT UNDER THIS SETUP APPEARS SEVERAL
HOURS OF FREEZING RAIN LIKELY BEGINNING EARLY MORNING NW...AND
TRANSITIONING WEST TO I-57 CORRIDOR BY LATE MORNING.  AS DEPTH OF
COLD AIR CONTINUES TO INCREASE THROUGH THE DAY A BRIEF PERIOD OF
SLEET IS LIKELY...THEN A CHANGEOVER TO ALL SNOW BY AFTERNOON WEST OF
I-55.  HUGE MODEL DISCREPANCIES ON HOW MUCH PRECIP TO LINGER IN COLD
AIRMASS.  NAM IS MOST BULLISH WITH STRONG MID LEVEL FRONTOGENESIS
INDUCING HEAVY PRECIP RATES WITH SIGNIFICANT ICE ACCUMULATIONS
FOLLOWED BY HEAVY SNOW.  GFS ON THE OTHER HAND MOVES MOST OF THE
PRECIP EAST AS DEEP COLD AIR ARRIVES.  MOST EUROPEAN MODELS SUPPORT
MORE PROGRESSIVE GFS SOLUTION.  NAM IS ALSO SEVERAL HOURS SLOWER
WITH SYSTEM WHICH MAKES SENSE GIVEN SYSTEM STRENGTHENING.  FOR NOW
FEEL THAT NAM HAS A GOOD HANDLE ON MAIN SYNOPTIC FORCING FEATURES BUT IS
OVER-BULLISH ON QPF AND WRAPPING UP A PHASED SYSTEM SO QUICKLY.  HPC
LEANING THIS DIRECTION AS WELL.  GIVEN VERY WARM GROUND TEMPS
FREEZING RAIN MAY HAVE A TOUGH TIME ACCUMULATING AT THE SFC DURING
THE DAY...THOUGH TREES AND POWERLINES COULD BE A DIFFERENT STORY.
THEREFORE SOME ICE ACCUM POSSIBLE ON THESE SFCS BEFORE CHANGEOVER TO
SNOW LATER IN THE DAY WITH SOME SNOW ACCUMULATION POSSIBLE AFTERNOON
INTO OVERNIGHT.  ONE MORE MODEL RUN SHOULD BE ABLE TO PIN DOWN
AMOUNTS BETTER AS MAIN VORT IS BETTER SAMPLED BY UA NETWORK
TONIGHT.  SNOW TO TAPER OFF OVERNIGHT INTO FRIDAY MORNING FROM NW TO
SE...WITH POSSIBLE ACCUMULATIONS OF A FEW INCHES...PRIMARILY EAST OF
THE IL RIVER.  A VERY WINTER-LIKE DAY TO BE FELT ON FRIDAY WITH
HIGHS NOT MAKING IT OUT OF THE L/M 30S WITH A NORTHWESTERLY
BREEZE.
LONG TERM...SATURDAY THROUGH TUESDAY...
FEW CHANGES MADE TO THE EXTENDED WITH GENERALLY QUIET WEATHER AND
WELL BELOW NORMAL TEMPERATURES.  TROUGH EXPECTED TO MOVE THROUGH THE
GREAT LAKES THIS WEEKEND AND PROVIDE A RE-ENFORCING SHOT OF COLD AIR
TO THE REGION BY SUNDAY.  850MB TEMPS TO PLUNGE INTO A -10 TO -15C
RANGE FOR LATE SUNDAY AND MONDAY PRODUCING JANUARY-LIKE TEMPS.
&&
.ILX WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SCHAFFER

FXUS63 KILX 290259
AFDILX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE LINCOLN IL
900 PM CST TUE NOV 28 2006
.DISCUSSION...
LOW CLOUDS HAVE OVERSPREAD MOST OF THE AREA...EXCEPT ALONG THE
ILLINOIS RIVER AND TO THE NORTHEAST. THEREFORE SOME ADJUSTMENTS WILL
BE MADE TO THE CLOUD COVER IN THE GRIDS...WHICH SHOULD GET REFLECTED
IN THE WORDING IN SOME WAY. THIS LACK OF CLOUDS WILL ALSO DECREASE
CHANCES OF ANY PCPN MOST OF THE NIGHT...UNTIL THE FRONT ARRIVES
TOMORROW MORNING. SO WILL ALSO ADJUST THE POP AND WX GRIDS. THOUGH
FRONT APPEARS TO BE MOVING QUICKER THAN EARLIER MODELS
INDICATED...IT STILL WONT GET INTO CWA UNTIL TOMORROW AND CURRENT
WIND FORECAST APPEARS TO BE INLINE WITH NEW 00Z FORECASTS...SO NO
ADJUSTMENTS HERE. FINALLY...OVERNIGHT LOWS APPEAR TO BE ON TRACK
WITH CLOUDS COVERING MOST OF THE AREA...SOUTHERLY WINDS REMAINING 15
TO 20 MPH...AND DEWPOINTS IN THE MIDDLE 50S. THEREFORE NO ADJUSTMENT
NEEDED HERE.
THEREFORE...CONSIDERING EVERYTHING MENTIONED ABOVE...AN UPDATE FOR
CLOUD COVER...POP...WX SHOULD BE OUT SHORTLY.
&&
.PREV DISCUSSION...
INTERESTING AND COMPLEX WEATHER SCENARIO TO UNFOLD OVER CENTRAL IL
OVER THE NEXT 48+ HOURS AS WE TRANSITION FROM MID-FALL TO MID-WINTER
CONDITIONS.  OBVIOUS FORECAST CHALLENGE IS POTENT MID TO LATE WEEK
STORM SYSTEM WHICH LOOKS TO PROVIDE PLENTY OF PRECIP...BOTH IN
LIQUID AND FROZEN STATES.  SHARP COOLOFF FROM UNSEASONABLY WARM
CONDITIONS FOR LAST WEEK OR SO...TO UNSEASONABLY COLD BY END OF THE
WEEK WITH PASSAGE OF STRONG COLD FRONT.  MAJOR SHIFT IN MOST FORECAST
MODELS LAST 12 HOURS...TRENDING TO A MORE PROGRESSIVE AND WEAKER
/FARTHER SE/ THURSDAY SYSTEM...SIGNIFICANTLY IMPACTING FROZEN PRECIP
LOCATION AND AMOUNTS.
EARLY AFTERNOON SURFACE ANALYSIS SHOWING WEAKLY ORGANIZED LOW
PRESSURE OVER MN...WITH A COLD FRONT EXTENDING SOUTHWARD INTO
NERN KS.  AHEAD OF THIS SYSTEM...DEEP AND STRONG SOUTHERLY FLOW
TRANSPORTING 55-65F DEWPOINTS UP FROM EAST TX INTO WI.  DEEP TROUGH
EVIDENT ON WV IMAGERY OVER THE INTERMOUNTAIN WEST...WITH SEVERAL
WEAK SHORTWAVES RIPPLING OUT AHEAD OF THIS FEATURE IN BROAD AND
DIFLUENT UPPER LEVEL FLOW.  WAA/ISENTROPIC LIFT IN COMBINATION WITH
SHORTWAVES HELPING TO FIRE SOME LATE NOVEMBER CONVECTION OVER THE
UPPER MIDWEST EARLIER TODAY.  ANOTHER UNSEASONABLY WARM DAY
LOCALLY...WITH TEMPS STAYING A FEW DEGREES BELOW RECORD HIGHS
DESPITE PLENTY OF CLOUD COVER.
SHORT TERM...TONIGHT THROUGH FRIDAY...
SOUTHERLY FLOW AHEAD OF COLD FRONT AND PLENTY OF MID/LOW LEVEL
CLOUD COVER TO KEEP TEMPERATURES UNSEASONABLY WARM AGAIN
TONIGHT...APPROACHING RECORD WARM LOWS AT PIA /56/ AND LINCOLN /55/.
CANNOT RULE OUT SOME ISOLATED SHOWERS OVERNIGHT IN BROAD WAA REGIME
WITH THE HELP OF ANY SUBTLE SHORTWAVES SO HAVE INCLUDED A 30 POP
OVERNIGHT.  RAIN CHANCES INCREASE BY DAYBREAK ALONG AND NW OF THE IL
RIVER AS STRONG COLD FRONT APPROACHES...AND CONTINUE TO INCREASE TO
THE SE THROUGH THE AFTERNOON.  ANOTHER VERY WARM LATE NOVEMBER DAY
ON TAP AS FRONT ONLY BISECTS CWA BY LATE AFTERNOON.  EXTENT OF DEEP
MOISTURE INFLUX AND MID LEVEL LAPSE RATES MAKE THUNDER A GOOD BET
WITH ELEVATED CAPES AOA 500 J/KG DURING THE AFTERNOON. NOTED SPC
SLGT RISK ENCROACHING ON WESTERN CWA...WILL HAVE SOME GOOD SPEED
SHEAR TO WORK WITH SO COULD SEE A FEW REPORTS OF GUSTY WINDS WITH
THE STRONGEST STORMS.  RAIN WITH EMBEDDED THUNDERSTORMS TO CONTINUE
OVERNIGHT AS STRONG SYNOPTIC SCALE LIFT ENHANCES PRECIP BEHIND COLD
FRONT.
REAL FUN AND HEADACHES BEGIN EARLY THURSDAY MORNING AS BL TEMPS BEGIN
TO COOL BELOW FREEZING NEAR GBG AS SHALLOW ARCTIC AIR...LAGGING MAIN
FRONT...MAKES IT/S MOVE.  NOT A CLASSIC FREEZING RAIN SETUP...OR
CLIMATOLOGICALLY FAVORED...BUT UNDER THIS SETUP APPEARS SEVERAL
HOURS OF FREEZING RAIN LIKELY BEGINNING EARLY MORNING NW...AND
TRANSITIONING WEST TO I-57 CORRIDOR BY LATE MORNING.  AS DEPTH OF
COLD AIR CONTINUES TO INCREASE THROUGH THE DAY A BRIEF PERIOD OF
SLEET IS LIKELY...THEN A CHANGEOVER TO ALL SNOW BY AFTERNOON WEST OF
I-55.  HUGE MODEL DISCREPANCIES ON HOW MUCH PRECIP TO LINGER IN COLD
AIRMASS.  NAM IS MOST BULLISH WITH STRONG MID LEVEL FRONTOGENESIS
INDUCING HEAVY PRECIP RATES WITH SIGNIFICANT ICE ACCUMULATIONS
FOLLOWED BY HEAVY SNOW.  GFS ON THE OTHER HAND MOVES MOST OF THE
PRECIP EAST AS DEEP COLD AIR ARRIVES.  MOST EUROPEAN MODELS SUPPORT
MORE PROGRESSIVE GFS SOLUTION.  NAM IS ALSO SEVERAL HOURS SLOWER
WITH SYSTEM WHICH MAKES SENSE GIVEN SYSTEM STRENGTHENING.  FOR NOW
FEEL THAT NAM HAS A GOOD HANDLE ON MAIN SYNOPTIC FORCING FEATURES BUT IS
OVER-BULLISH ON QPF AND WRAPPING UP A PHASED SYSTEM SO QUICKLY.  HPC
LEANING THIS DIRECTION AS WELL.  GIVEN VERY WARM GROUND TEMPS
FREEZING RAIN MAY HAVE A TOUGH TIME ACCUMULATING AT THE SFC DURING
THE DAY...THOUGH TREES AND POWERLINES COULD BE A DIFFERENT STORY.
THEREFORE SOME ICE ACCUM POSSIBLE ON THESE SFCS BEFORE CHANGEOVER TO
SNOW LATER IN THE DAY WITH SOME SNOW ACCUMULATION POSSIBLE AFTERNOON
INTO OVERNIGHT.  ONE MORE MODEL RUN SHOULD BE ABLE TO PIN DOWN
AMOUNTS BETTER AS MAIN VORT IS BETTER SAMPLED BY UA NETWORK
TONIGHT.  SNOW TO TAPER OFF OVERNIGHT INTO FRIDAY MORNING FROM NW TO
SE...WITH POSSIBLE ACCUMULATIONS OF A FEW INCHES...PRIMARILY EAST OF
THE IL RIVER.  A VERY WINTER-LIKE DAY TO BE FELT ON FRIDAY WITH
HIGHS NOT MAKING IT OUT OF THE L/M 30S WITH A NORTHWESTERLY
BREEZE.
LONG TERM...SATURDAY THROUGH TUESDAY...
FEW CHANGES MADE TO THE EXTENDED WITH GENERALLY QUIET WEATHER AND
WELL BELOW NORMAL TEMPERATURES.  TROUGH EXPECTED TO MOVE THROUGH THE
GREAT LAKES THIS WEEKEND AND PROVIDE A RE-ENFORCING SHOT OF COLD AIR
TO THE REGION BY SUNDAY.  850MB TEMPS TO PLUNGE INTO A -10 TO -15C
RANGE FOR LATE SUNDAY AND MONDAY PRODUCING JANUARY-LIKE TEMPS.
&&
.ILX WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
AUTEN/SCHAFFER

FXUS63 KILX 290941
AFDILX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE LINCOLN IL
341 AM CST WED NOV 29 2006
.DISCUSSION...
SAME FORECAST ISSUES REMAIN...ONGOING PRECIP AHEAD OF AND ALONG A
COLD FRONT SWEEPING ACROSS THE MISSISSIPPI RIVER VALLEY THIS
MORNING.  SOUTHWESTERLY FLOW CONTINUES TO DOMINATE THE FLOW AS A
MAJOR TROF DIGS IN OVER THE ROCKIES. COLD FRONT CURRENTLY STRETCHED
FROM NORTH CENTRAL WISCONSIN...ALONG THE MISS RIVER VALLEY BACK THRU
NWRN MO AND INTO SERN KS. SHOWERY PRECIP ACROSS THE NWRN PORTIONS OF
THE STATE IN THE OVERNIGHT HOURS AS EMBEDDED WAVES MOVE THROUGH THE
SWRLY FLOW ALONG THE FRONTAL BOUNDARY. GFS AND 06Z NAM STARTING TO
COME INTO AGREEMENT THIS MORNING ABOUT THE TRACK OF THE SFC LOW.
ECMWF STILL SIGNIFICANTLY LACKING IN SFC LOW STRENGTH.  CANADIAN
GLOBAL STICKING TO ITS PREVIOUS FORECASTS.  NOT A LOT OF CHANGES TO
THE FORECAST AS A RESULT.  WWD HAS CHANGED WITH THE FORECAST OF THE
LOCATION OF THE HEAVIEST SNOWFALL WITH THE SHIFT OF THE SYSTEMS TO
THE SE.  CENTRAL FA IS MOST LIKELY TO BE AFFECTED IN LATEST RUN.
FROM THE ILLINOIS RIVER VALLEY SEWD TO INTERSTATE 57 COULD SEE
APPRECIABLE SNOW FALL TOTALS THU EVENING AND NIGHT.  AVOIDING
HEADLINES AT THIS POINT TO AVOID A LOT OF OSCILLATION.  LAST
NIGHT...HEAVIEST SNOW FALL WAS IN THE NW...TODAY IN THE SE...THIS
MORNING...ITS IN THE MIDDLE AND THE PENDULUM SEEMS TO BE ZEROING IN
ON A TARGET.  LET THE DAY SHIFT HAVE ONE MORE RUN AND ISSUE THE
HEADLINES WITH BETTER ACCURACY.  MAJOR SHIFT TO THE FORECAST IS TO
SHIFT THE SNOWFALL AMOUNTS TO THE CENTRAL ZONES...KEEPING ICE IN THE
NW...BUT ALSO THE LOWER POPS WELL BEHIND THE FRONT.
SHORT TERM...TODAY AND TONIGHT...
MODELS ARE NOT RESPONDING TO THE MORE RAPID PACE OF THE FRONT FROM
YESTERDAY EVENING.  WITH THE FRONT IN SLIGHTLY MORE PARALLEL
FLOW...A SLOWING TREND IS LIKELY...THOUGH SHORT TERM WILL HAVE TO
KEEP AN EYE ON THE AFFECTS ON THE DETAILS.  AS IT IS...WITH
OVERNIGHT TEMPS STILL IN THE LOW 60S AND UPPER 50S...HAVE GONE WITH
A LESS THAN DIURNAL TREND IN THE HOURLY TEMPS THROUGHOUT TODAY.
THEN THE TEMPS START TO DROP OFF FROM THE NW TO THE SE IN THE
OVERNIGHT HOURS TONIGHT WITH THE PASSAGE OF THE COLD FRONT.  SPC HAS
PAINTED A SLIGHT RISK OVER ALMOST THE ENTIRE CWA TODAY...SPARING
ONLY THE FAR EASTERN COUNTIES.  FROPA IS LIKELY WITH PLENTY OF
MOISTURE AND WARM TEMPS STILL IN PLACE...THOUGH IN THE OVERNIGHT AND
EVENING HOURS TONIGHT.  THOUGH FORECAST SOUNDINGS SHOW WEAK
INSTABILITY...COLD FRONT IS VERY STRONG AND INCREASINGLY STRONG
UNIDIRECTIONAL SHEAR WILL LEND ITSELF TO THE POSSIBILITY OF HAIL AND
SVR WINDS SHOULD THE THUNDERSTORMS ORGANIZE.
LONG TERM...THURSDAY THROUGH TUESDAY...
CHANCES FOR PRECIP WILL CONTINUE THROUGH THE EARLY MORNING HOURS ON
THURSDAY.  H5 TROF AND SFC LOW HANGING BACK A BIT UNTIL THURSDAY/THU
NIGHT AS IT MOVES IN.  WILL SEE A SWITCH TO WINTER PRECIP AS
THURSDAY PROGRESSES AND THE COLDER AIR EDGES IN FROM THE NW.
DEVELOPING SFC LOW IS MODELED TO RIDE UP THE COLD FRONT AT THE SFC.
THURSDAY NIGHT...THE H5 TROF MOVES OVER THE REGION...INTO A NEGATIVE
TILT.  OR AT LEAST...THE PAST FEW RUNS HAVE HINTED AT THIS.  LATEST
RUNS OF THE GFS AND NAM RAPIDLY DEVELOP THE SFC CYCLONE PRIOR TO THE
NEGATIVE TILT OF THE UPPER LEVEL TROF.  IN CONTRAST...THE ECMWF DOES
NOT RAPIDLY DEVELOP THE SFC CYCLONE UNTIL A MORE NEG TILT...BUT WELL
OFF TO THE NE.  THE VERY CONSISTENT (THOUGH ONCE AGAIN THE OUTLIER)
CANADIAN KEEPS THE WAVE WELL TO THE SOUTH AND EAST...RIDING UP THE
FRONT WHEN THE WEATHER IS WELL OUT OF THE AREA. KEEPING THE GOING
FORECAST WHICH IS A VERY CONSERVATIVE BLEND OF ECMWF AND GFS.
REMAINING FORECAST DRY AT THIS POINT...THOUGH BEGINNING TO SHOW A
SIGNAL OF POSSIBLE PRECIP FOR THE NRN TIER OF ILLINOIS LATE IN THE
WEEKEND AS ANOTHER UPPER LEVEL TROF MOVES THROUGH...WITH A
REINFORCING...ALBEIT BRIEF SHOT OF COLD AIR.  HAVE DROPPED TEMPS SUN
NIGHT AND MON SLIGHTLY OFF OF GUIDANCE AS A RESULT.  YET ANOTHER
TROF FORECAST FOR TUESDAY WITH A LITTLE MORE LAYER RH COULD RESULT
IN POPS BEING ADDED NEXT RUN.
&&
.ILX WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
HJS

FXUS63 KILX 291635
AFDILX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE LINCOLN IL
1034 AM CST WED NOV 29 2006
.DISCUSSION...
16Z SURFACE ANALYSIS SHOWS NEARLY STATIONARY FRONTAL BOUNDARY ACROSS
WEST-CENTRAL ILLINOIS.  WINDS HAVE SWITCHED TO NORTHWESTERLY AT BOTH
MACOMB AND GALESBURG...WITH TEMPS DROPPING INTO THE 40S.  FURTHER
EAST...UNSEASONABLY WARM AIRMASS STILL IN PLACE ACROSS THE REST OF
THE KILX CWA...WITH TEMPS MAINLY IN THE MIDDLE 60S.  SHOWERS AND
ISOLATED THUNDERSTORMS CONTINUE TO TRACK ALONG THE FRONT ACROSS THE
ILLINOIS RIVER.  STRONGER STORMS ARE NOTED FURTHER SOUTHWEST ALONG
THE BOUNDARY ACROSS CENTRAL MISSOURI AND THESE STORMS SHOULD REACH
THE FAR W/SW CWA SHORTLY AFTER 11AM...THEN SPREAD UP THE ILLINOIS
RIVER INTO THE AFTERNOON.  INSTABILITY IS SOMEWHAT LIMITED...HOWEVER
IMPRESSIVE WIND FIELDS AND STEEP MID-LEVEL LAPSE RATES...SUGGEST THE
APPROACHING STORMS COULD PRODUCE DAMAGING WIND GUSTS AND HAIL.  WITH
FRONT REMAINING NEARLY STATIONARY UNTIL LATE THIS AFTERNOON...THE
BULK OF THE SHOWERS/STORMS WILL REMAIN ALONG AND WEST OF I-55.  HAVE
THEREFORE BUMPED POPS UP CONSIDERABLY ACROSS THESE AREAS.  HAVE ALSO
ADJUSTED TEMP GRIDS A BIT...FEATURING NEARLY STEADY TEMPS ACROSS THE
FAR W/NW...WITH HIGHS CLIMBING INTO THE UPPER 60S ELSEWHERE.
&&
.PREV DISCUSSION...
SAME FORECAST ISSUES REMAIN...ONGOING PRECIP AHEAD OF AND ALONG A
COLD FRONT SWEEPING ACROSS THE MISSISSIPPI RIVER VALLEY THIS
MORNING.  SOUTHWESTERLY FLOW CONTINUES TO DOMINATE THE FLOW AS A
MAJOR TROF DIGS IN OVER THE ROCKIES. COLD FRONT CURRENTLY STRETCHED
FROM NORTH CENTRAL WISCONSIN...ALONG THE MISS RIVER VALLEY BACK THRU
NWRN MO AND INTO SERN KS. SHOWERY PRECIP ACROSS THE NWRN PORTIONS OF
THE STATE IN THE OVERNIGHT HOURS AS EMBEDDED WAVES MOVE THROUGH THE
SWRLY FLOW ALONG THE FRONTAL BOUNDARY. GFS AND 06Z NAM STARTING TO
COME INTO AGREEMENT THIS MORNING ABOUT THE TRACK OF THE SFC LOW.
ECMWF STILL SIGNIFICANTLY LACKING IN SFC LOW STRENGTH.  CANADIAN
GLOBAL STICKING TO ITS PREVIOUS FORECASTS.  NOT A LOT OF CHANGES TO
THE FORECAST AS A RESULT.  WWD HAS CHANGED WITH THE FORECAST OF THE
LOCATION OF THE HEAVIEST SNOWFALL WITH THE SHIFT OF THE SYSTEMS TO
THE SE.  CENTRAL FA IS MOST LIKELY TO BE AFFECTED IN LATEST RUN.
FROM THE ILLINOIS RIVER VALLEY SEWD TO INTERSTATE 57 COULD SEE
APPRECIABLE SNOW FALL TOTALS THU EVENING AND NIGHT.  AVOIDING
HEADLINES AT THIS POINT TO AVOID A LOT OF OSCILLATION.  LAST
NIGHT...HEAVIEST SNOW FALL WAS IN THE NW...TODAY IN THE SE...THIS
MORNING...ITS IN THE MIDDLE AND THE PENDULUM SEEMS TO BE ZEROING IN
ON A TARGET.  LET THE DAY SHIFT HAVE ONE MORE RUN AND ISSUE THE
HEADLINES WITH BETTER ACCURACY.  MAJOR SHIFT TO THE FORECAST IS TO
SHIFT THE SNOWFALL AMOUNTS TO THE CENTRAL ZONES...KEEPING ICE IN THE
NW...BUT ALSO THE LOWER POPS WELL BEHIND THE FRONT.
SHORT TERM...TODAY AND TONIGHT...
MODELS ARE NOT RESPONDING TO THE MORE RAPID PACE OF THE FRONT FROM
YESTERDAY EVENING.  WITH THE FRONT IN SLIGHTLY MORE PARALLEL
FLOW...A SLOWING TREND IS LIKELY...THOUGH SHORT TERM WILL HAVE TO
KEEP AN EYE ON THE AFFECTS ON THE DETAILS.  AS IT IS...WITH
OVERNIGHT TEMPS STILL IN THE LOW 60S AND UPPER 50S...HAVE GONE WITH
A LESS THAN DIURNAL TREND IN THE HOURLY TEMPS THROUGHOUT TODAY.
THEN THE TEMPS START TO DROP OFF FROM THE NW TO THE SE IN THE
OVERNIGHT HOURS TONIGHT WITH THE PASSAGE OF THE COLD FRONT.  SPC HAS
PAINTED A SLIGHT RISK OVER ALMOST THE ENTIRE CWA TODAY...SPARING
ONLY THE FAR EASTERN COUNTIES.  FROPA IS LIKELY WITH PLENTY OF
MOISTURE AND WARM TEMPS STILL IN PLACE...THOUGH IN THE OVERNIGHT AND
EVENING HOURS TONIGHT.  THOUGH FORECAST SOUNDINGS SHOW WEAK
INSTABILITY...COLD FRONT IS VERY STRONG AND INCREASINGLY STRONG
UNIDIRECTIONAL SHEAR WILL LEND ITSELF TO THE POSSIBILITY OF HAIL AND
SVR WINDS SHOULD THE THUNDERSTORMS ORGANIZE.
LONG TERM...THURSDAY THROUGH TUESDAY...
CHANCES FOR PRECIP WILL CONTINUE THROUGH THE EARLY MORNING HOURS ON
THURSDAY.  H5 TROF AND SFC LOW HANGING BACK A BIT UNTIL THURSDAY/THU
NIGHT AS IT MOVES IN.  WILL SEE A SWITCH TO WINTER PRECIP AS
THURSDAY PROGRESSES AND THE COLDER AIR EDGES IN FROM THE NW.
DEVELOPING SFC LOW IS MODELED TO RIDE UP THE COLD FRONT AT THE SFC.
THURSDAY NIGHT...THE H5 TROF MOVES OVER THE REGION...INTO A NEGATIVE
TILT.  OR AT LEAST...THE PAST FEW RUNS HAVE HINTED AT THIS.  LATEST
RUNS OF THE GFS AND NAM RAPIDLY DEVELOP THE SFC CYCLONE PRIOR TO THE
NEGATIVE TILT OF THE UPPER LEVEL TROF.  IN CONTRAST...THE ECMWF DOES
NOT RAPIDLY DEVELOP THE SFC CYCLONE UNTIL A MORE NEG TILT...BUT WELL
OFF TO THE NE.  THE VERY CONSISTENT (THOUGH ONCE AGAIN THE OUTLIER)
CANADIAN KEEPS THE WAVE WELL TO THE SOUTH AND EAST...RIDING UP THE
FRONT WHEN THE WEATHER IS WELL OUT OF THE AREA. KEEPING THE GOING
FORECAST WHICH IS A VERY CONSERVATIVE BLEND OF ECMWF AND GFS.
REMAINING FORECAST DRY AT THIS POINT...THOUGH BEGINNING TO SHOW A
SIGNAL OF POSSIBLE PRECIP FOR THE NRN TIER OF ILLINOIS LATE IN THE
WEEKEND AS ANOTHER UPPER LEVEL TROF MOVES THROUGH...WITH A
REINFORCING...ALBEIT BRIEF SHOT OF COLD AIR.  HAVE DROPPED TEMPS SUN
NIGHT AND MON SLIGHTLY OFF OF GUIDANCE AS A RESULT.  YET ANOTHER
TROF FORECAST FOR TUESDAY WITH A LITTLE MORE LAYER RH COULD RESULT
IN POPS BEING ADDED NEXT RUN.
&&
.ILX WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
BARNES/HJS

FXUS63 KILX 292100
AFDILX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE LINCOLN IL
300 PM CST WED NOV 28 2006
.DISCUSSION...
MAJOR WINTER STORM TO AFFECT MUCH OF THE MIDWEST STARTING AS RAIN
TONIGHT THEN TRANSITIONING TO FREEZING RAIN AND SLEET ON THURSDAY
AND POSSIBLY HEAVY SNOW OVERNIGHT INTO FRIDAY MORNING.  THIS SYSTEM
HAS THE POTENTIAL TO PRODUCE SIGNIFICANT ICE ACCUMULATIONS OVER
PORTIONS OF CENTRAL IL....FOLLOWED BY HEAVY SNOW POSSIBLY IN EXCESS
OF ONE FOOT TO THE WEST OF I-55.
POTENT UPPER LEVEL SYSTEM NOW ROUNDING BASE OF TROUGH IN 4 CORNERS
REGION INDUCING CYCLOGENESIS OVER CENTRAL TX.  FRONTAL BOUNDARY
EXTENDS NORTHEASTWARD TO SOUTHERN LAKE MICHIGAN.  COLD FRONT IS
EXPECTED TO SLOW OVER THE NEXT 24 HOURS IN RESPONSE TO STRONG LOW
PRESSURE DEVELOPMENT OVER SOUTHERN MISSISSIPPI VALLEY.  TIGHT
BAROCLINIC ZONE AND POTENT COUPLED UPPER LEVEL JET STREAM ACTING IN
A MOISTURE-RICH ATMOSPHERE TO PRODUCE COPIOUS AMOUNTS OF
PRECIPITATION.
SHORT TERM...TONIGHT THROUGH FRIDAY...
STRONG MOISTURE ADVECTION OVER FRONT TO PRODUCE WIDESPREAD RAINS
OVERNIGHT AS COLD AIR SLOWLY SEEPS IN FROM THE  NORTHWEST. PRECIP
EXPECTED TO BEGIN TO CHANGE OVER TO FREEZING RAIN NORTHWEST OF THE
IL RIVER VERY LATE TONIGHT THROUGH DAYBREAK.  ARRIVAL OF COLD AIR
DELAYED BY SEVERAL HOURS THAN PREVIOUSLY THOUGHT AS STRONGER
CYCLOGENESIS SLOWS MOVEMENT OF FRONT.  FORECAST SOUNDINGS NOW
SUGGEST CHANGE TO FREEZING RAIN AND SLEET TO REACH THE I-55 CORRIDOR
BY MIDDAY...AND NOT MAKING MUCH FATHER EASTWARD PROGRESSION BY LATE
AFTERNOON.  AN EXTENDED PERIOD OF THIS MIXED PRECIP APPEARS LIKELY
IN THESE AREAS WITH A SIGNIFICANT WARM WEDGE OF +2 TO +6C RANGE IN
THE 700-850MB LAYER.  ICE ACCUMULATIONS OF AT LEAST A TENTH OF AN
INCH APPEAR POSSIBLE...THOUGH WARM GROUND MAY HINDER
ACCUMULATIONS... BUT ELEVATED SURFACES /TREES POWERLINES CARS/ COULD
BE AT RISK FOR ICING ESPECIALLY AFTER SUNSET.  NORTHWEST EDGE OF
PRECIP SHIELD PROGGED TO SETTLE SOUTH OF THE IL RIVER DURING THE
AFTERNOON...GIVING A BRIEF RESPITE.  STRONG DYNAMIC FORCING BEGINS
TO TAKE OVER THURSDAY NIGHT IN RESPONSE TO AMAZING COUPLED JET
STRUCTURE OVER IL /CWA IN LFQ OF 140KT STREAK STREAK NOSING INTO
SOUTHERN IL...AND RRQ OF 130KT JET STREAK OVER CENTRAL GREAT
LAKES/.  STRONG PVA AND OTHER QG FORCING PARAMETERS NEARLY OFF THE
CHARTS OVERNIGHT INTO FRIDAY MORNING AS LOW WRAPS UP FROM SOUTHERN
IL INTO WEST CENTRAL IN.  THUNDER APPEARS LIKELY WITH SUCH STRONG
FORCING...SO MAY SEE PERIODS OF THUNDER SLEET AND SNOW.  BEST
DYNAMIC FORCING AND COLD AIR FOR DENDRITIC GROWTH WILL BE FOUND
ALONG AND WEST OF THE IL RIVER AFTER MIDNIGHT THROUGH THE EARLY
MORNING HOURS...WITH SNOWFALL RATES OF 1-2"+ PER HOUR NOT OUT OF THE
QUESTION.  FARTHER EAST TO THE I-57 CORRIDOR A SNOW/SLEET MIX
APPEARS LIKELY AFTER MIDNIGHT WITH NARROWING AND LESS INTENSE WARM
INTRUSION ALOFT.  SOUTH OF I-70...LIQUID PRECIP SHOULD DOMINATE
UNTIL EARLY FRIDAY MORNING...WHEN A QUICK CHANGE TO SNOW SHOULD
OCCUR.  TROWAL PROGGED TO SET UP ACROSS THE WESTERN AND CENTRAL CWA
ON FRIDAY MORNING TO ADD TO SNOW TOTALS.  WITH VERY GOOD AGREEMENT
AMONG SHORT AND MEDIUM-RANGE MODELS WILL HOIST WINTER STORM WARNING
ALONG AND WEST OF THE I-55 CORRIDOR WITH 6-12" ACCUMULATIONS
POSSIBLE BY MIDDAY FRIDAY.  ENHANCED MESOSCALE BANDING WILL LIKELY
PRODUCE LOCALIZED AREAS WITH SEVERAL ADDITIONAL INCHES.  WILL
MAINTAIN CURRENT WATCH ALONG AND EAST OF THIS LINE AS WARM AIR ALOFT
AND DRY SLOT ISSUES REMAIN TO BE RESOLVED.  DO BELIEVE THE DRY SLOT
WILL SET UP BETWEEN I-55 AND I-57 CORRIDORS TO LIMIT ACCUMULATIONS
ONCE PROFILE COOLS ENOUGH ON FRIDAY MORNING.
NORTHWESTERLY WINDS OF 15-25KTS WILL PRODUCE CONSIDERABLE BLOWING
AND DRIFTING SNOW INTO FRIDAY AFTERNOON IN THE HEAVY SNOW
BAND.
LONG TERM...SATURDAY THROUGH TUESDAY...
NO CHANGES MADE TO THE EXTENDED WITH GENERALLY QUIET AND COLD
WEATHER TO DOMINATE.
&&
.ILX WATCHES/WARNINGS/ADVISORIES...
ILZ027>030-036-040...WINTER STORM WARNING IN EFFECT FROM 3AM
THURSDAY THROUGH NOON FRIDAY.
ILZ031-037-038-041-042-047>051...WINTER STORM WARNING IN EFFECT FROM
9AM THURSDAY THROUGH NOON FRIDAY.
ILZ043>046-052>057-061...WINTER STORM WATCH IN EFFECT THURSDAY
AFTERNOON THROUGH FRIDAY MORNING.
ILZ062-063-066>068-071>073...WINTER STORM WATCH IN EFFECT THURSDAY
AFTERNOON THROUGH FRIDAY MORNING.
&&
$$
SCHAFFER

FXUS63 KILX 300303
AFDILX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE LINCOLN IL
900 PM CST WED NOV 28 2006
.DISCUSSION...
QUASI-STATIONARY FRONT HAS ONLY MOVED FROM THE IL RIVER TO I-55 IN
THE PAST 6-8HRS. RAIN AND THUNDERSTORMS...AND LOTS OF LOW CLOUDS
CONTINUE ALONG AND BEHIND THE FRONT...WITH AREAS NORTHWEST OF THE IL
RIVER RECEIVING THE MOST PCPN TODAY. WITH THE FRONT SLOWLY
PROGRESSING TO THE EAST/SOUTHEAST THE PCPN SHOULD ALSO SLOWLY EXPAND
TO THE EAST OVERNIGHT.
TEMPS BELOW FREEZING HAVE GOTTEN INTO EASTERN IA AND NORTHEAST MO
DURING PAST SEVERAL HOURS AND EXPECT THIS TO EASTWARD PROGRESS TO
CONTINUE OVERNIGHT INTO NORTHWESTERN AND WEST CENTRAL IL. FORECASTED
HOURLY TEMPS ABOUT 3-5 DEGS TOO WARM...COMPARED TO MSAS TO PCPN
COULD CHANGE TO FREEZING RAIN A FEW HOURS SOONER THAN EXPECTED.
HOWEVER...WITH GROUND TEMPS AROUND 50F...IT MAY STILL TAKE A COUPLE
OF HOURS FOR SURFACE TO START FREEZING...EXCEPT FOR EXPOSED
SURFACES...LIKE POWER LINES AND OVERPASSES.
NEW MODEL DATA STILL COMING IN AND HAVE NOT BEEN ABLE TO DIGEST ALL.
PLUS CURRENT FORECAST APPEARS TO BE CLOSELY ON TRACK. THEREFORE NO
UPDATE PLANNED IN THE FORECAST FOR TONIGHT. HOWEVER...WILL BE
UPDATING WINTER STORM WARNING AND WATCH IN THE NEXT 30 MINS.
&&
.PREV DISCUSSION...
MAJOR WINTER STORM TO AFFECT MUCH OF THE MIDWEST STARTING AS RAIN
TONIGHT THEN TRANSITIONING TO FREEZING RAIN AND SLEET ON THURSDAY
AND POSSIBLY HEAVY SNOW OVERNIGHT INTO FRIDAY MORNING.  THIS SYSTEM
HAS THE POTENTIAL TO PRODUCE SIGNIFICANT ICE ACCUMULATIONS OVER
PORTIONS OF CENTRAL IL....FOLLOWED BY HEAVY SNOW POSSIBLY IN EXCESS
OF ONE FOOT TO THE WEST OF I-55.
POTENT UPPER LEVEL SYSTEM NOW ROUNDING BASE OF TROUGH IN 4 CORNERS
REGION INDUCING CYCLOGENESIS OVER CENTRAL TX.  FRONTAL BOUNDARY
EXTENDS NORTHEASTWARD TO SOUTHERN LAKE MICHIGAN.  COLD FRONT IS
EXPECTED TO SLOW OVER THE NEXT 24 HOURS IN RESPONSE TO STRONG LOW
PRESSURE DEVELOPMENT OVER SOUTHERN MISSISSIPPI VALLEY.  TIGHT
BAROCLINIC ZONE AND POTENT COUPLED UPPER LEVEL JET STREAM ACTING IN
A MOISTURE-RICH ATMOSPHERE TO PRODUCE COPIOUS AMOUNTS OF
PRECIPITATION.
SHORT TERM...TONIGHT THROUGH FRIDAY...
STRONG MOISTURE ADVECTION OVER FRONT TO PRODUCE WIDESPREAD RAINS
OVERNIGHT AS COLD AIR SLOWLY SEEPS IN FROM THE  NORTHWEST. PRECIP
EXPECTED TO BEGIN TO CHANGE OVER TO FREEZING RAIN NORTHWEST OF THE
IL RIVER VERY LATE TONIGHT THROUGH DAYBREAK.  ARRIVAL OF COLD AIR
DELAYED BY SEVERAL HOURS THAN PREVIOUSLY THOUGHT AS STRONGER
CYCLOGENESIS SLOWS MOVEMENT OF FRONT.  FORECAST SOUNDINGS NOW
SUGGEST CHANGE TO FREEZING RAIN AND SLEET TO REACH THE I-55 CORRIDOR
BY MIDDAY...AND NOT MAKING MUCH FATHER EASTWARD PROGRESSION BY LATE
AFTERNOON.  AN EXTENDED PERIOD OF THIS MIXED PRECIP APPEARS LIKELY
IN THESE AREAS WITH A SIGNIFICANT WARM WEDGE OF +2 TO +6C RANGE IN
THE 700-850MB LAYER.  ICE ACCUMULATIONS OF AT LEAST A TENTH OF AN
INCH APPEAR POSSIBLE...THOUGH WARM GROUND MAY HINDER
ACCUMULATIONS... BUT ELEVATED SURFACES /TREES POWERLINES CARS/ COULD
BE AT RISK FOR ICING ESPECIALLY AFTER SUNSET.  NORTHWEST EDGE OF
PRECIP SHIELD PROGGED TO SETTLE SOUTH OF THE IL RIVER DURING THE
AFTERNOON...GIVING A BRIEF RESPITE.  STRONG DYNAMIC FORCING BEGINS
TO TAKE OVER THURSDAY NIGHT IN RESPONSE TO AMAZING COUPLED JET
STRUCTURE OVER IL /CWA IN LFQ OF 140KT STREAK STREAK NOSING INTO
SOUTHERN IL...AND RRQ OF 130KT JET STREAK OVER CENTRAL GREAT
LAKES/.  STRONG PVA AND OTHER QG FORCING PARAMETERS NEARLY OFF THE
CHARTS OVERNIGHT INTO FRIDAY MORNING AS LOW WRAPS UP FROM SOUTHERN
IL INTO WEST CENTRAL IN.  THUNDER APPEARS LIKELY WITH SUCH STRONG
FORCING...SO MAY SEE PERIODS OF THUNDER SLEET AND SNOW.  BEST
DYNAMIC FORCING AND COLD AIR FOR DENDRITIC GROWTH WILL BE FOUND
ALONG AND WEST OF THE IL RIVER AFTER MIDNIGHT THROUGH THE EARLY
MORNING HOURS...WITH SNOWFALL RATES OF 1-2"+ PER HOUR NOT OUT OF THE
QUESTION.  FARTHER EAST TO THE I-57 CORRIDOR A SNOW/SLEET MIX
APPEARS LIKELY AFTER MIDNIGHT WITH NARROWING AND LESS INTENSE WARM
INTRUSION ALOFT.  SOUTH OF I-70...LIQUID PRECIP SHOULD DOMINATE
UNTIL EARLY FRIDAY MORNING...WHEN A QUICK CHANGE TO SNOW SHOULD
OCCUR.  TROWAL PROGGED TO SET UP ACROSS THE WESTERN AND CENTRAL CWA
ON FRIDAY MORNING TO ADD TO SNOW TOTALS.  WITH VERY GOOD AGREEMENT
AMONG SHORT AND MEDIUM-RANGE MODELS WILL HOIST WINTER STORM WARNING
ALONG AND WEST OF THE I-55 CORRIDOR WITH 6-12" ACCUMULATIONS
POSSIBLE BY MIDDAY FRIDAY.  ENHANCED MESOSCALE BANDING WILL LIKELY
PRODUCE LOCALIZED AREAS WITH SEVERAL ADDITIONAL INCHES.  WILL
MAINTAIN CURRENT WATCH ALONG AND EAST OF THIS LINE AS WARM AIR ALOFT
AND DRY SLOT ISSUES REMAIN TO BE RESOLVED.  DO BELIEVE THE DRY SLOT
WILL SET UP BETWEEN I-55 AND I-57 CORRIDORS TO LIMIT ACCUMULATIONS
ONCE PROFILE COOLS ENOUGH ON FRIDAY MORNING.
NORTHWESTERLY WINDS OF 15-25KTS WILL PRODUCE CONSIDERABLE BLOWING
AND DRIFTING SNOW INTO FRIDAY AFTERNOON IN THE HEAVY SNOW
BAND.
LONG TERM...SATURDAY THROUGH TUESDAY...
NO CHANGES MADE TO THE EXTENDED WITH GENERALLY QUIET AND COLD
WEATHER TO DOMINATE.
&&
.ILX WATCHES/WARNINGS/ADVISORIES...
ILZ027>030-036-040...WINTER STORM WARNING IN EFFECT FROM 3AM
THURSDAY THROUGH NOON FRIDAY.
ILZ031-037-038-041-042-047>051...WINTER STORM WARNING IN EFFECT FROM
9AM THURSDAY THROUGH NOON FRIDAY.
ILZ043>046-052>057-061...WINTER STORM WATCH IN EFFECT THURSDAY
AFTERNOON THROUGH FRIDAY MORNING.
ILZ062-063-066>068-071>073...WINTER STORM WATCH IN EFFECT THURSDAY
AFTERNOON THROUGH FRIDAY MORNING.
&&
$$
AUTEN/SCHAFFER

FXUS63 KILX 300942
AFDILX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE LINCOLN IL
341 AM CST THU NOV 30 2006
.DISCUSSION...
WINTER IS HERE...OR WILL BE VERY SHORTLY.  COLD AIR ALREADY COMING
INTO NWRN AREAS OF THE CWA BUT PRECIP FOR THE MOMENT ACROSS THE
CENTRAL AND SOUTHEAST.  PRECIP STILL FALLING AS RAIN AT THE
MOMENT...BUT THE BIG ISSUE FOR THE FORECAST WILL BE THE PRECIP TYPE
AND SNOWFALL TOTALS. MODELS COMING INTO AGREEMENT FINALLY...AND 12Z
ECMWF IS FAVORED BY HPC FOR THE GUIDANCE...NOT STRAYING TOO FAR FROM
THE CONSENSUS.  WINTER STORM WARNINGS ARE OUT FOR MUCH OF THE
FA...WITH THE EXCEPTION OF THE FAR SE..ALONG AND SOUTH OF INTERSTATE
70...WHERE AN ADVISORY WILL BE IN EFFECT FOR TONIGHT AND EARLY
FRIDAY.  FOR THE REMAINING FA...SIGNIFICANT ICE ACCUMULATION AND
SNOW TOTALS WILL AFFECT THE AREA TODAY THROUGH FRIDAY MORNING.
SHORT TERM...TODAY AND TOMORROW...
FRONT CURRENTLY DRAPED ACROSS THE CENTRAL FA...WILL CONTINUE TO
DRIFT THROUGHOUT THE DAY SLOWLY TO THE SE...ALLOWING FOR COLD AIR
FILTERING IN BEHIND IT TO SLOWLY CHANGE OVER THE RAIN FROM THE
MORNING TO FREEZING RAIN AND SOME SLEET.  ICE ACCUMULATIONS OF A
QUARTER OF AN INCH ARE POSSIBLE.  AREAS ALONG AND NW OF INTERSTATE
55 ARE MOST LIKELY TO SEE THE BEST ACCUMULATION OF ICE. GROUND
TEMPERATURES ARE RELATIVELY WARM AND MANY STREETS WILL NOT HAVE A
PROBLEM INITIALLY AS ICE ACCUMULATES ON TREES...POWER LINES...AND
ELEVATED SURFACES...INCLUDING BRIDGES.  THAT WILL ONLY HOLD OUT FOR
SO LONG THOUGH AND EVENTUALLY WILL SEE MORE ACCUMULATION ON ROADS AS
WELL INTO THE AFTERNOON AND EARLY EVENING.
A SURFACE LOW IS RIDING UP THE FRONT TODAY FROM THE SRN PLAINS...AND
WILL BE COLLIDING WITH OUR AREA AND A NEGATIVELY TILTED UPPER LEVEL
TROF THIS EVENING...RAPIDLY INTENSIFYING THE CYCLONE OVER THE
MIDWEST.  THE FZRA WILL EVENTUALLY SWITCH OVER TO SNOW THIS EVENING
AND LATE TONIGHT.  MOST AREAS NORTHWEST OF A CHAMPAIGN TO
SHELBYVILLE LINE WILL SEE THE MAJORITY OF SNOW ACCUMULATIONS AFTER
MIDNIGHT.  AREAS TO THE SE HAVE AN ADVISORY IN EFFECT STARTING AFTER
6PM FOR THE INITIAL CHANGEOVER TO FZRA AND SLEET...AND WILL SEE A
CHANGEOVER TO SNOW IN THE EARLY MORNING HOURS.
WINDS ACROSS THE AREA WILL BE QUITE INTENSE FROM MIDNIGHT THROUGH
THE EARLY MORNING HOURS AS THE DEEPENING SFC SYSTEM RESULTS IN A
INCREASING PRESSURE GRADIENT AND WINDS IN EXCESS OF 25KTS.  SNOW AND
BLOWING SNOW COULD BE A CONCERN AS THESE TWO CONDITIONS COINCIDE TO
AREAS ALONG AND NW OF INTERSTATE 55 AFTER MIDNIGHT. WIND CHILLS ARE
GOING TO BE IN THE SINGLE DIGITS IN THE MORNING HOURS OF FRIDAY.
BUNDLE UP OR STAY INSIDE.
AS FOR THE SNOW...MODELS ARE IN RELATIVE AGREEMENT AT THIS
POINT...WITH EVEN THE ECMWF AND THE CANADIAN FINALLY JOINING THE
PARTY AND PUTTING IN THE DEFORMATION ZONE ACROSS CENTRAL ILLINOIS IN
THE OVERNIGHT HOURS TONIGHT.  MODELS DIFFER SLIGHTLY FROM RUN TO RUN
AS TO WHERE THE ACTUAL HEAVIEST SNOW WILL FALL.  FOR THE MOST
PART...THEY ARE AGREEING WITH THE ILLINOIS RIVER VALLEY TO THE
INTERSTATE 55 CORRIDOR. SNOWFALL TOTALS FOR THE WHOLE EVENT  AROUND
A FOOT IN SOME LOCATIONS... WITH SOME ISOLATED HIGHER AMOUNTS. AREAS
TO THE EAST OF INTERSTATE 55 WILL LIKELY SEE A SHARP DROP OFF IN THE
AMOUNTS OF SNOW...WITH 3-6 INCHES.  ALONG AND SOUTH OF INTERSTATE
70...EVEN LIGHTER. BUT ALL PLACES WITH A COATING OF ICE PRIOR TO
THIS WILL CAUSE SOME SERIOUS TRAVELING PROBLEMS. SNOW WILL
EVENTUALLY TAPER OFF IN THE EARLY AFTERNOON HOURS ON FRIDAY.
LONG TERM...SATURDAY THROUGH WEDNESDAY...
DROPPED TEMPS SLIGHTLY FOR THE REALITY OF A SNOWPACK ACROSS THE AREA
FOR THE NEXT COUPLE OF DAYS...WARMING UP THE SE FIRST WHERE THE SNOW
SHOULD BE THE THINNEST.
MOST OF THE REMAINING FORECAST DRY AT THIS POINT.  YET ANOTHER TROF
FORECAST FOR TUESDAY WITH A LITTLE MORE LAYER RH.  ADDED LOW 30 POP
FOR NRN 2/3RDS OF FA.
&&
.ILX WATCHES/WARNINGS/ADVISORIES...
ILZ027>031-036>038-040>043-047>053-
KNOX-STARK-PEORIA-MARSHALL-FULTON-SCHUYLER-WOODFORD-TAZEWELL-
MCLEAN-MASON-LOGAN-CASS-MENARD-SCOTT-MORGAN-SANGAMON- DE WITT-
CHRISTIAN-MACON-
...WINTER STORM WARNING IN EFFECT THROUGH NOON FRIDAY.
ILZ044>046-054>057-061-
PIATT-CHAMPAIGN-VERMILION-MOULTRIE-DOUGLAS-COLES-EDGAR-SHELBY-
...WINTER STORM WARNING IN EFFECT THURSDAY AFTERNOON AT 1PM THROUGH
NOON FRIDAY.
ILZ062-063-066>068-071>073-
CUMBERLAND-CLARK-EFFINGHAM-JASPER-CRAWFORD-CLAY-RICHLAND-LAWRENCE-
...WINTER WEATHER ADVISORY IN EFFECT THURSDAY EVENING AT 6PM THROUGH
NOON FRIDAY.
&&
$$
HJS
 

FXUS63 KILX 301647
AFDILX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE LINCOLN IL
1045 AM CST THU NOV 30 2006
.UPDATE...
WILL BE UPDATING THE ZFP AND GRIDS BASED ON CURRENT TRENDS.  12Z
RAOBS FROM KILX AND KDVN INDICATE QUITE A BIT OF COLDER AND DRIER
AIR WORKING INTO THE WESTERN REACHES OF THE CWA.  AS A RESULT...
EXPECTING JUST ISOLATED TO SCATTERED BOUTS OF PRECIP NORTHWEST OF A
BEARDSTOWN-LINCOLN-BLOOMINGTON LINE.
SHORT RANGE MODELS IN GOOD AGREEMENT ON STALLING OUT THE BACK EDGE
OF PRECIP SOMEWHERE BETWEEN THE I-55 AND I-72 CORRIDORS FOR THE
REMAINDER OF THE MORNING AND AFTERNOON HOURS... WITH WESTERN AREAS
OF THE I-72 CORRIDOR... INCLUDING SPRINGFIELD... STAYING RIGHT ON
THE EDGE.
EVENTUALLY THE PRECIP WILL RETURN FROM THE SOUTH AS OUR MAIN SFC LOW
GETS GOING.  IT IS CURRENTLY CENTERED OVER SOUTHWESTERN ARKANSAS.  3
AND 6-HR ISALLOBARS SHOW LITTLE DEEPENING SO FAR... BUT THE STORM
SHOULD BEGIN TO DEEPEN RAPIDLY AS THE STRONG SHORTWAVE OVER CENTRAL
TEXAS SHIFTS EASTWARD.  IN ADDITION... A COUPLED JET STRUCTURE
BETWEEN THE POLAR AND SUBTROPICAL JETS OVER THE OHIO VALLEY WILL
PROMOTE RAPID DEEPENING OF THE SFC LOW THROUGH TONIGHT.
PRECIP TYPE THROUGH THIS AFTERNOON...
FARTHER BACK IN THE COLDER AND DRIER AIR... SOME ISO-SCAT LIGHT SNOW
AND SLEET SHOWERS WILL BE POSSIBLE THROUGH THIS AFTERNOON.  AREAS
AROUND SPRINGFIELD AND ALONG THE I-55 CORRIDOR SHOULD SEE FREEZING
RAIN AND FRZ DRIZZLE CONTINUE THROUGH THIS AFTERNOON... WITH BEST
CHANCES OF ACCUMULATIONS IN THE SPRINGFIELD AREA.
THE COLDER AIR HAS SLOWED ITS MARCH EASTWARD SOMEWHAT OVER THE PAST
COUPLE OF HOURS.  WITH CMI AND DEC STILL AT 35 AND 34 DEGREES
RESPECTIVELY.  STILL SOME RISK OF SEEING PRECIP CHANGING OVER TO
FREEZING RAIN IN CMI AND DEC BY MID AFTERNOON AS THE COLDER AIR
SLOWLY MOVES EASTWARD.
LATEST TRENDS WITH OVERNIGHT SITUATION...
12Z NAM AND GFS HAVE BEEN SHOWING A SLOWER TREND WITH OUR SFC LOW...
WHICH ALLOWS THE LOW TO TAKE A FARTHER WEST TRACK... AND PULL IN
WARMER AIR BACK ACROSS THE EASTERN HALF OF THE CWA AS THE LOW IS
ALLOWED TO BECOME DEEPER AND MORE WRAPPED UP.
SHOULD THIS TREND PAN OUT... IT INTRODUCES THE POSSIBILITY OF A
PROLONGED ICING PROBLEM OVERNIGHT THROUGH THE CENTRAL PORTIONS OF
THE CWA... INCLUDING THE 1-55 CORRIDOR.  THE COLDER AIR IS STILL
EXPECTED TO REMAIN DEEPLY ENTRENCHED ENOUGH ACROSS THE WEST TO KEEP
THE HEAVY SNOW THREAT IN FOR THE ILLINOIS RIVER VALLEY.
IT IS IMPORTANT TO NOTE THAT THUS FAR THE NCEP MODELS HAVE NOT
HANDLED THE DEPTH AND EASTWARD PROGRESS OF THE COLD AIR SO FAR WITH
THIS EVENT.  HOWEVER... THERE ARE SIGNS NOW THAT THE COLD AIRS
EASTWARD PROGRESS HAS SLOWED... AND THE SFC LOW OVER ARKANSAS IS
MOVING A LITTLE SLOWER AS WELL.
FOR NOW... WE WILL KEEP THE GOING FORECAST AS-IS FOR THE OVERNIGHT
HOURS... PENDING FURTHER ANALYSIS AND COORDINATION.  HEADLINES ARE
NOT EXPECTED TO CHANGE AT THIS POINT... BUT ADJUSTMENTS TO THE
EXPECTED WX ELEMENTS WITHIN THE WINTER STORM WARNING CRITERIA ARE
POSSIBLE WITH THE EVENING PACKAGE.
&&
.PREV DISCUSSION...
/ISSUED 341 AM CST THU NOV 30 2006/
WINTER IS HERE...OR WILL BE VERY SHORTLY.  COLD AIR ALREADY COMING
INTO NWRN AREAS OF THE CWA BUT PRECIP FOR THE MOMENT ACROSS THE
CENTRAL AND SOUTHEAST.  PRECIP STILL FALLING AS RAIN AT THE
MOMENT...BUT THE BIG ISSUE FOR THE FORECAST WILL BE THE PRECIP TYPE
AND SNOWFALL TOTALS. MODELS COMING INTO AGREEMENT FINALLY...AND 12Z
ECMWF IS FAVORED BY HPC FOR THE GUIDANCE...NOT STRAYING TOO FAR FROM
THE CONSENSUS.  WINTER STORM WARNINGS ARE OUT FOR MUCH OF THE
FA...WITH THE EXCEPTION OF THE FAR SE..ALONG AND SOUTH OF INTERSTATE
70...WHERE AN ADVISORY WILL BE IN EFFECT FOR TONIGHT AND EARLY
FRIDAY.  FOR THE REMAINING FA...SIGNIFICANT ICE ACCUMULATION AND
SNOW TOTALS WILL AFFECT THE AREA TODAY THROUGH FRIDAY MORNING.
SHORT TERM...TODAY AND TOMORROW...
FRONT CURRENTLY DRAPED ACROSS THE CENTRAL FA...WILL CONTINUE TO
DRIFT THROUGHOUT THE DAY SLOWLY TO THE SE...ALLOWING FOR COLD AIR
FILTERING IN BEHIND IT TO SLOWLY CHANGE OVER THE RAIN FROM THE
MORNING TO FREEZING RAIN AND SOME SLEET.  ICE ACCUMULATIONS OF A
QUARTER OF AN INCH ARE POSSIBLE.  AREAS ALONG AND NW OF INTERSTATE
55 ARE MOST LIKELY TO SEE THE BEST ACCUMULATION OF ICE. GROUND
TEMPERATURES ARE RELATIVELY WARM AND MANY STREETS WILL NOT HAVE A
PROBLEM INITIALLY AS ICE ACCUMULATES ON TREES...POWER LINES...AND
ELEVATED SURFACES...INCLUDING BRIDGES.  THAT WILL ONLY HOLD OUT FOR
SO LONG THOUGH AND EVENTUALLY WILL SEE MORE ACCUMULATION ON ROADS AS
WELL INTO THE AFTERNOON AND EARLY EVENING.
A SURFACE LOW IS RIDING UP THE FRONT TODAY FROM THE SRN PLAINS...AND
WILL BE COLLIDING WITH OUR AREA AND A NEGATIVELY TILTED UPPER LEVEL
TROF THIS EVENING...RAPIDLY INTENSIFYING THE CYCLONE OVER THE
MIDWEST.  THE FZRA WILL EVENTUALLY SWITCH OVER TO SNOW THIS EVENING
AND LATE TONIGHT.  MOST AREAS NORTHWEST OF A CHAMPAIGN TO
SHELBYVILLE LINE WILL SEE THE MAJORITY OF SNOW ACCUMULATIONS AFTER
MIDNIGHT.  AREAS TO THE SE HAVE AN ADVISORY IN EFFECT STARTING AFTER
6PM FOR THE INITIAL CHANGEOVER TO FZRA AND SLEET...AND WILL SEE A
CHANGEOVER TO SNOW IN THE EARLY MORNING HOURS.
WINDS ACROSS THE AREA WILL BE QUITE INTENSE FROM MIDNIGHT THROUGH
THE EARLY MORNING HOURS AS THE DEEPENING SFC SYSTEM RESULTS IN A
INCREASING PRESSURE GRADIENT AND WINDS IN EXCESS OF 25KTS.  SNOW AND
BLOWING SNOW COULD BE A CONCERN AS THESE TWO CONDITIONS COINCIDE TO
AREAS ALONG AND NW OF INTERSTATE 55 AFTER MIDNIGHT. WIND CHILLS ARE
GOING TO BE IN THE SINGLE DIGITS IN THE MORNING HOURS OF FRIDAY.
BUNDLE UP OR STAY INSIDE.
AS FOR THE SNOW...MODELS ARE IN RELATIVE AGREEMENT AT THIS
POINT...WITH EVEN THE ECMWF AND THE CANADIAN FINALLY JOINING THE
PARTY AND PUTTING IN THE DEFORMATION ZONE ACROSS CENTRAL ILLINOIS IN
THE OVERNIGHT HOURS TONIGHT.  MODELS DIFFER SLIGHTLY FROM RUN TO RUN
AS TO WHERE THE ACTUAL HEAVIEST SNOW WILL FALL.  FOR THE MOST
PART...THEY ARE AGREEING WITH THE ILLINOIS RIVER VALLEY TO THE
INTERSTATE 55 CORRIDOR. SNOWFALL TOTALS FOR THE WHOLE EVENT  AROUND
A FOOT IN SOME LOCATIONS... WITH SOME ISOLATED HIGHER AMOUNTS. AREAS
TO THE EAST OF INTERSTATE 55 WILL LIKELY SEE A SHARP DROP OFF IN THE
AMOUNTS OF SNOW...WITH 3-6 INCHES.  ALONG AND SOUTH OF INTERSTATE
70...EVEN LIGHTER. BUT ALL PLACES WITH A COATING OF ICE PRIOR TO
THIS WILL CAUSE SOME SERIOUS TRAVELING PROBLEMS. SNOW WILL
EVENTUALLY TAPER OFF IN THE EARLY AFTERNOON HOURS ON FRIDAY.
LONG TERM...SATURDAY THROUGH WEDNESDAY...
DROPPED TEMPS SLIGHTLY FOR THE REALITY OF A SNOWPACK ACROSS THE AREA
FOR THE NEXT COUPLE OF DAYS...WARMING UP THE SE FIRST WHERE THE SNOW
SHOULD BE THE THINNEST.
MOST OF THE REMAINING FORECAST DRY AT THIS POINT.  YET ANOTHER TROF
FORECAST FOR TUESDAY WITH A LITTLE MORE LAYER RH.  ADDED LOW 30 POP
FOR NRN 2/3RDS OF FA.
&&
.ILX WATCHES/WARNINGS/ADVISORIES...
ILZ027>031-036>038-040>043-047>053-
KNOX-STARK-PEORIA-MARSHALL-FULTON-SCHUYLER-WOODFORD-TAZEWELL-
MCLEAN-MASON-LOGAN-CASS-MENARD-SCOTT-MORGAN-SANGAMON- DE WITT-
CHRISTIAN-MACON-
...WINTER STORM WARNING IN EFFECT THROUGH NOON FRIDAY.
ILZ044>046-054>057-061-
PIATT-CHAMPAIGN-VERMILION-MOULTRIE-DOUGLAS-COLES-EDGAR-SHELBY-
...WINTER STORM WARNING IN EFFECT THURSDAY AFTERNOON AT 1PM THROUGH
NOON FRIDAY.
ILZ062-063-066>068-071>073-
CUMBERLAND-CLARK-EFFINGHAM-JASPER-CRAWFORD-CLAY-RICHLAND-LAWRENCE-
...WINTER WEATHER ADVISORY IN EFFECT THURSDAY EVENING AT 6PM THROUGH
NOON FRIDAY.
&&
$$
HARDIMAN/HJS
 

FXUS63 KILX 302037
AFDILX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE LINCOLN IL
237 PM CST THU NOV 30 2006
.DISCUSSION...MAJOR WINTER STORM CONTINUES TO DEVELOP ACROSS THE
NATION/S MID SECTION AND WILL BE THE MAIN WEATHER CONCERN OVER THE
NEXT SEVERAL DAYS. LATEST SURFACE ANALYSIS HAD DEEPENING LOW
PRESSURE CENTERED OVER ARKANSAS...WITH A FRONTAL BOUNDARY EXTENDING
NORTHEAST FROM THE LOW INTO NEW ENGLAND. MEANWHILE...STRONG/COLD
HIGH PRESSURE WAS CENTERED OVER THE NORTHERN PLAINS. ALOFT...BROAD
TROFFING WAS IN PLACE ACROSS MUCH OF THE UNITED STATES...WITH A
VIGOROUS UPPER LOW CENTERED OVER NORTHERN TEXAS.
12Z MODELS IN GOOD OVERALL AGREEMENT OVER THE NEXT SEVERAL DAYS...
THOUGH THE NAM IS A BIT SLOWER IN LIFTING THE UPPER/SURFACE LOW
THROUGH THE MIDWEST TONIGHT AND TOMORROW. HOWEVER...THE MODEL
DIFFERENCES ARE MORE NOTABLE IN THE THERMAL PROFILES. DO NOT HAVE
GREAT CONFIDENCE IN ANY OF THE THERMAL SOLUTIONS GIVEN THEIR WARM
INITIALIZATIONS AND POOR DEPICTION OF THE SHALLOW SURFACE BASED COLD
LAYER.
SHORT TERM...
TONIGHT AND FRIDAY...SURFACE LOW WILL CONTINUE TO RAPIDLY DEEPEN
TONIGHT AS UPPER TROF TAKES ON A NEGATIVE TILT AND LIFTS NORTHEAST.
SURFACE/UPPER LOWS ARE PROGGED TO REACH THE MIDWEST BY 12Z FRIDAY
AND SOUTHERN ONTARIO BY 00Z SATURDAY.
MAINLY LIQUID PRECIPITATION IS EXPECTED THIS EVENING IN ADVANCE OF
THE APPROACHING SYSTEM. THIS PRECIPITATION WILL FREEZE ON CONTACT IN
THE MANY LOCATIONS THAT HAVE FALLEN BELOW FREEZING (MAINLY WEST OF
I-57). THE BULK OF THE ICE ACCUMULATION THUS FAR HAS BEEN LIMITED TO
OBJECTS ABOVE THE GROUND (GROUND TEMPERATURES STILL TOO WARM FOR
SIGNIFICANT ICE ACCRETION). AS THE STRENGTHENING SYSTEM PASSES
THROUGH ILLINOIS OVERNIGHT THE HEAVIEST PRECIPITATION IS EXPECTED...
ALONG WITH A GRADUAL TRANSITION TO SNOW FROM WEST TO EAST. THE
FORCING IS IMPRESSIVE DUE TO A COUPLED JET STRUCTURE...STRONG
DPVA...AND FRONTOGENETIC FORCING IN THE SYSTEM/S DEFORMATION ZONE.
THE HEAVIEST SNOWFALL IS EXPECTED ALONG AND WEST OF THE ILLINOIS
RIVER VALLEY WHERE THE PRECIPITATION IS EXPECTED TO BE ALL SNOW.
THIS AREA IS ALSO WHERE THE DEFORMATION ZONE WILL LINGER THE LONGEST
AND THE THREAT FOR BANDED SNOW THE HIGHEST.
THE SNOW WILL TAPER OFF BY MIDDAY FRIDAY AS THE DRY SLOT MOVES IN
AND/OR THE DEFORMATION ZONE MOVES OUT. HOWEVER...GUSTY NORTHWEST
WINDS ON THE BACK SIDE OF THE DEPARTING SYSTEM WILL CAUSE BLOWING
AND DRIFTING OF THE FALLEN SNOW.
FRIDAY NIGHT THROUGH SUNDAY...COLD HIGH PRESSURE WILL BUILD ACROSS
THE REGION DURING THE REMAINDER OF THE SHORT TERM PERIOD...
ACCOMPANIED BY PERSISTENT NORTHWEST FLOW ALOFT. THIS SCENARIO SHOULD
PROVIDE QUIET BUT COOL CONDITIONS.
LONG TERM...MONDAY THROUGH THURSDAY...MODELS/ENSEMBLES IN REASONABLE
AGREEMENT THROUGH THE PERIOD WITH RESPECT TO FEATURES EXPECTED TO
IMPACT REGION. AT LEAST SOME DEGREE OF TROFFING IS EXPECTED TO BE IN
PLACE ALOFT...WITH A CLIPPER OR TWO POSSIBLE. MODEL CONSENSUS
SUGGESTS ANY CLIPPERS WILL BE TOO FAR NORTH TO BE MUCH OF A
PRECIPITATION RISK (OF COURSE THIS MAY CHANGE). TEMPERATURES SHOULD
REMAIN AT BELOW NORMAL LEVELS.
&&
.ILX WATCHES/WARNINGS/ADVISORIES...
WINTER STORM WARNING IN EFFECT UNTIL 12 PM CST FRIDAY FOR COUNTIES
NORTH OF AN EFFINGHAM TO CLARK COUNTY LINE.
&&
$$
BAK