MESOSCALE DISCUSSION 2501
   NWS STORM PREDICTION CENTER NORMAN OK
   0548 AM CST MON DEC 06 2004
   
   AREAS AFFECTED...PORTIONS OF WRN /CENTRAL NY AND NCENTRAL PA
   
   CONCERNING...WINTER MIXED PRECIPITATION 
   
   VALID 061148Z - 061745Z
   
   MODERATE SNOW WILL DEVELOP ACROSS PORTIONS OF WRN/CENTRAL NY THROUGH
   18Z...WITH A MIX OF FREEZING RAIN/SLEET THE PREDOMINANT PTYPES
   ACROSS NCENTRAL PA. SNOW SHOULD CHANGE OVER TO FREEZING RAIN/SLEET
   NWD INTO SCENTRAL/SWRN NY AND PORTIONS OF NERN PA BETWEEN 15-18Z.
   HOURLY ACCUMULATIONS AROUND 0.03-0.05 INCH LIQUID EQUIVALENT IS
   ANTICIPATED TO BE COMMON ACROSS THE AREA FOR AT LEAST A 2-4 HR
   PERIOD.
   
   REGIONAL RADAR IMAGERY INDICATES THAT LIGHT PRECIPITATION CONTINUES
   TO SPREAD RAPIDLY ENEWD ACROSS ERN MI AND NERN OH. 11Z SFC ANALYSIS
   SHOWS THE SFC FREEZING LINE EXTENDING ACROSS FAR SWRN NY SEWD TO
   NEAR STATE COLLEGE...WITH THE WET BULB FREEZING LINE ABOUT 50 MILES
   SOUTH OF THIS AXIS. A COMBINATION OF MODERATE WARM ADVECTION IN THE
   1-3 KM LAYER EVIDENT BY REGIONAL VWP/S OVER THE OHIO VALLEY AND EWD
   MOVEMENT OF THE MID LEVEL FRONTOGENESIS FORCING OVER CENTRAL/ERN MI
   WILL SUPPORT NEWD DEVELOPMENT OF LIGHT TO MODERATE PRECIPITATION
   INTO THE AREA THROUGH THE MORNING HOURS. MODERATE SNOWFALL
   ASSOCIATED WITH FRONTOGENETICALLY FORCED BANDS IN THE 600-700 MB
   LAYER OVER CENTRAL MI WILL BEGIN TO MOVE INTO WRN NY BETWEEN 12-15Z.
   FARTHER SOUTH...WHERE LOW LEVEL WAA WILL BE THE DOMINANT FORCING
   MECHANISM...0-0.5 KM ENELY FLOW AND NUMEROUS NARROW VALLEY/S IN THE
   REGION WILL SUPPORT COLD AIR BEING LOCKED IN WITH THE POTENTIAL FOR
   FREEZING RAIN AND/OR SLEET AS ELEVATED WARM LAYER OVERSPREADS THE
   AREA THROUGH THE MID-MORNING. THIS LOW LEVEL COLD DRAINAGE SHOULD
   ALSO LIMIT THE NWD MOVEMENT OF THE FREEZING LINE THROUGH THE
   MORNING. AS THE ELEVATED WARM LAYER GRADUALLY SHIFTS NWD THROUGH
   DURING THE MID-LATE MORNING...SNOW OVER PORTIONS OF SWRN/SCENTRAL NY
   AND NERN PA SHOULD THEN GRADUALLY BECOME MIXED WITH SLEET AND
   POSSIBLY FREEZING RAIN BY 18Z.
   
   ..CROSBIE.. 12/06/2004
   
   
   ...NOTICE...
   SPC WINTER WEATHER MESOSCALE DISCUSSIONS WILL BE ISSUED ON A 
   SCHEDULED BASIS...FOUR TIMES A DAY...BETWEEN 05-06 UTC...
   11-12 UTC...17-18 UTC...AND 23-00 UTC AS SIGNIFICANT SHORT
   RANGE WINTER WEATHER EVENTS UNFOLD.  THIS SCHEDULE WILL BE
   USED FROM DECEMBER 1 THROUGH FEBRUARY 28 TO ALLOW PARTNERS
   AND USERS TO BETTER ANTICIPATE THE TIMING OF SPC WINTER WEATHER
   MESOSCALE DISCUSSIONS.
   
   ATTN...WFO...BGM...BUF...CTP...PBZ...
   
   43317774 43217842 42397900 41787919 41297886 41157810
   41077623 41507553 42137529 42757546 43337592