MESOSCALE DISCUSSION 2279
   NWS STORM PREDICTION CENTER NORMAN OK
   0512 AM CST MON DEC 31 2007
   
   AREAS AFFECTED...PORTIONS OF WRN INTO DOWN EAST MAINE
   
   CONCERNING...HEAVY SNOW 
   
   VALID 311112Z - 311515Z
   
   THE POTENTIAL FOR LOCALLY HEAVY SNOWFALL WITH HOURLY RATES
   APPROACHING ONE INCH WILL EXIST ACROSS DISCUSSION AREA INTO MID
   MORNING.  SNOWFALL INTENSITY SHOULD BEGIN TO DECREASE FROM WEST TO
   EAST ACROSS REGION BEGINNING AROUND 12Z.
   
   AS OF 1045Z...REGIONAL RADAR IMAGERY INDICATED A BAND OF POTENTIALLY
   HEAVY SNOW FROM PARTS OF N-CNTRL AND NERN MA THROUGH SERN NH AND
   ACROSS PARTS OF WRN INTO DOWN EAST ME...EMBEDDED WITHIN LARGER-SCALE
   PRECIPITATION FIELD MOVING 230/40-50 KT.  SHORT TERM NAM/RUC
   DIAGNOSTIC FIELDS INDICATE THAT THIS BAND OF HEAVIER PRECIPITATION
   IS WELL CORRELATED WITH A SIMILARLY ORIENTED REGION OF
   FRONTOGENETICAL FORCING /AS SEEN IN NORMAL F-VECTOR CONVERGENCE
   FIELDS/ WHICH IS MOST PROMINENT IN THE 850-700 MB LAYER.  THIS
   FORCING IS FORECAST TO MAXIMIZE AROUND 12Z...PRIOR TO SHIFTING NEWD
   INTO THE CANADIAN MARITIMES...TO THE NW OF SURFACE LOW TRACK.
   
   WHILE RUC PROXIMITY SOUNDINGS SUGGEST THAT THERMODYNAMIC ENVIRONMENT
   SHOULD REMAIN LARGELY STABLE TO UPRIGHT PARCEL ACCELERATIONS...THERE
   APPEARS TO BE SOME POTENTIAL FOR SLANTWISE INSTABILITIES GIVEN
   POCKETS OF NEUTRAL TO SLIGHTLY NEGATIVE MOIST POTENTIAL VORTICITY. 
   THIS WOULD SERVE TO ENHANCE ABOVEMENTIONED...MESOSCALE BRANCH OF
   ASCENT...EFFECTIVELY PROMOTING LOCALLY HIGHER SNOW RATES.
   
   A FAIRLY RAPID CESSATION OF THE HEAVIER SNOW SHOULD BEGIN BY 12Z
   OVER SWRN ME WITH THIS TREND CONTINUING NEWD ACROSS DISCUSSION AREA
   THROUGH THE MID TO LATE MORNING HOURS.
   
   ..MEAD.. 12/31/2007
   
   
   ...NOTICE...
   SPC WINTER WEATHER MESOSCALE DISCUSSIONS WILL BE ISSUED ON A
   SCHEDULED BASIS FROM DECEMBER 1 THROUGH FEBRUARY 28...FOUR
   TIMES A DAY...AROUND 00 UTC...06 UTC...12 UTC...AND 18 UTC
   FOR SIGNIFICANT SHORT RANGE WINTER WEATHER EVENTS.
   
   ATTN...WFO...CAR...GYX...
   
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