MESOSCALE DISCUSSION 2570
   NWS STORM PREDICTION CENTER NORMAN OK
   1257 AM CST THU DEC 23 2004
   
   AREAS AFFECTED...MUCH OF KY/IND...MIDDLE TN....SERN MI...OH AND FAR
   NWRN PA/SWRN NY
   
   CONCERNING...PRECIPITATION TRENDS...WINTER PRECIPITATION 
   
   VALID 230657Z - 231200Z
   
   SIGNIFICANT WINTER STORM WILL CONTINUE TO DEVELOP NEWD FROM THE OHIO
   VALLEY INTO THE ERN GREAT LAKES REGION THROUGH 12Z. MOD-HVY SNOW
   WITH HRLY RATES AT TIMES ABOVE 1 INCH WILL OCCUR OVER MUCH OF
   IND/WRN OH AND SERN LOWER MI...WITH A NARROWING TRANSITION ZONE OF
   SLEET FROM CENTRAL KY NWD INTO NCENTRAL OH...AND A ZONE OF FREEZING
   RAIN FROM PORTIONS OF MIDDLE TN NEWD INTO SWRN NY/NWRN PA. GIVEN THE
   RAPID PROGRESSIVE NATURE OF THIS SYSTEM HVY SNOW WILL DIMINISH OVER
   MOST OF IND BY 10Z AND SERN OH BY 12Z. MODERATE FREEZING RAIN OVER
   MIDDLE TN/CENTRAL KY WILL TRANSITION TO LIGHT SNOW AND BEFORE ENDING
   BY 12Z.
   
   MID LEVEL FRONTOGENESIS IN THE 650-550 MB LAYER AIDED BY STRONG
   LOW-MID LEVEL WAA PROFILE BENEATH AN AMPLIFYING NEGATIVELY TILTED
   UPPER TROUGH WILL CONTINUE TO FOCUS BANDS OF HVY SNOW OVER
   CENTRAL/SRN IND...WCENTRAL OH THROUGH 10Z...WHILE DEVELOPING NEWD
   INTO FAR SERN MI AND NWRN OH. AS A STRONG MID LEVEL DRY SLOT CLEARLY
   EVIDENT ON IR/WV SAT IMAGERY MOVES IN BEHIND UPPER TROUGH ...EXPECT
   A RAPID DEMISE OF MOD-HVY SNOW FROM SW-NE THROUGH 12Z.
   
   SOUTH OF THIS AREA OF MOD-HVY SNOW...A MIX OF SLEET AND FREEZING
   RAIN WILL CONTINUE ALONG A 40-60 MILE WIDE CORRIDOR FROM MIDDLE TN
   NEWD INTO FAR SWRN NY/NWRN PA THROUGH 09Z. RECENT 06Z SOUNDING FROM
   BNA INDICATES A SUBSTANTIAL ELEVATED WARM LAYER ABOVE THE SHALLOW
   SUBFREEZING LAYER IN THE POST SFC COLD FRONTAL ENVIRONMENT.  AXIS OF
   THIS MIX PRECIP ZONE WILL BECOME MORE NORTH-SOUTH ORIENTED THROUGH
   12Z...AS UPPER TROUGH CONTINUES TO EJECT NEGATIVELY TILTED AND
   STRENGTHENS LOW LEVEL CAA/FRONTAL INVERSION AND THE SFC LOW LIFTS
   NWD TOWARDS CNTRL LAKE ERIE. IN ADDITION THE ELEVATED FREEZING LAYER
    AND MIX PTYPE ZONE NORTH OF SFC COLD/STATIONARY FRONT WILL NARROW
   THROUGH 12Z. AS A RESULT OF THE RAPID MOTION OF THE UPPER
   TROUGH...AND LOW LEVEL CAA..FREEZING RAIN SHOULD CHANGE OVER TO
   SLEET AND EVENTUALLY LIGHT TO MOD SNOW FROM MIDDLE TN NWD ACROSS
   NCENTRAL KY. FURTHER NEWD...MOVEMENT OF SFC LOW FROM SCENTRAL KY
   INTO NWRN PA...EVIDENT BY AXIS OF STRONGEST PRESSURE FALLS AT
   06Z...WILL RESULT IN PORTIONS OF NCENTRAL/NERN OH SEEING A CHANGE
   FROM LIGHT-MOD SNOW TO FREEZING RAIN/SLEET. NERN/ECENTRAL OH...FAR
   NWRN PA AND SWRN NY SHOULD SEE A GRADUAL WWD MVMNT OF THE SFC
   FREEZING LINE/WARM FRONT AND A TRANSITION FROM FREEZING RAIN TO RAIN
   THROUGH 12Z
   
   ..CROSBIE.. 12/23/2004
   
   
   ...NOTICE...
   SPC WINTER WEATHER MESOSCALE DISCUSSIONS WILL BE ISSUED ON A 
   SCHEDULED BASIS...FOUR TIMES A DAY...BETWEEN 00-01 UTC...
   06-07 UTC...12-13 UTC...AND 18-19 UTC AS SIGNIFICANT SHORT
   RANGE WINTER WEATHER EVENTS UNFOLD.  THIS SCHEDULE WILL BE
   USED FROM DECEMBER 1 THROUGH FEBRUARY 28.
   
   ATTN...WFO...BUF...CTP...PBZ...RLX...CLE...MRX...JKL...ILN...DTX...LMK...IWX...OHX...IND...PAH...ILX...
   
   43327796 42007955 40488092 38658304 36438446 36208528
   36148613 36488724 37708805 38758797 40568580 42128400
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