MESOSCALE DISCUSSION 2262
   NWS STORM PREDICTION CENTER NORMAN OK
   0625 PM CST SAT DEC 19 2009
   
   AREAS AFFECTED...NJ...SERN PA...NRN DE...SRN NY...CT...RI...SRN MA
   
   CONCERNING...HEAVY SNOW 
   
   VALID 200025Z - 200530Z
   
   HEAVY SNOW WITH RATES OF 1 TO 2 IN/HR WILL PIVOT NEWD FROM THE
   MID-ATLANTIC INTO SRN NEW ENGLAND THROUGH 06Z. THE MOST PERSISTENT
   AREA OF HEAVY SNOW SHOULD LIE ACROSS PORTIONS OF THE NEW YORK CITY
   METRO AREA...LONG ISLAND AND CT...WITH LOCALIZED RATES EXCEEDING 2
   IN/HR AT TIMES. OCCASIONAL BLIZZARD CONDITIONS SHOULD COMMENCE
   ACROSS THE ERN HALF OF LONG ISLAND AND SRN CT/RI/MA.
   
   984 MB SURFACE CYCLONE CENTERED AROUND 150 SM E OF THE DELMARVA
   PENINSULA HAS REMAINED NEARLY STEADY-STATE OVER THE PAST 12 HOURS.
   NEVERTHELESS...AFTERNOON MODEL FORECASTS ARE CONSISTENT THAT
   DEEPENING OF THIS LOW WILL OCCUR THROUGH THE 00-06Z PERIOD AS THE
   MID-ATLANTIC SHORT WAVE TROUGH AMPLIFIES. THIS WILL LEAD TO
   STRENGTHENING OF MID-LEVEL FRONTOGENESIS AND ISENTROPIC
   ASCENT...COINCIDENT WITH THE DENDRITIC GROWTH LAYER...DEVELOPING
   NEWD INTO SRN NEW ENGLAND. AS A RESULT...ONGOING MODERATE TO HEAVY
   SNOW FALLING ALONG THE I-95 CORRIDOR FROM THE WASHINGTON D.C. TO NEW
   YORK CITY METRO AREAS WILL PIVOT NEWD. PERSISTENT SNOWFALL RATES OF
   1 TO 2 IN/HR WILL BE LIKELY FROM NJ NEWD INTO CT/RI THROUGH
   06Z...WITH EMBEDDED BANDS SUPPORTING RATES BRIEFLY EXCEEDING 2
   IN/HR.
   
   AS THE OFFSHORE CYCLONE DEEPENS AND SLOWLY TRACKS NEWD...TIGHTENING
   OF THE LOW-LEVEL PRESSURE GRADIENT WILL STRENGTHEN N/NELY SURFACE
   FLOW. FREQUENT GUSTS AOA 35 MPH SHOULD REMAIN CONFINED TO THE ERN
   PORTION OF LONG ISLAND INTO COASTAL CT/RI AND FAR SRN MA...SUPPORTED
   BY 15Z SREF GUIDANCE. THIS SHOULD LEAD TO THE COMMENCEMENT OF
   BLIZZARD CONDITIONS /ESPECIALLY TOWARDS 06Z/ AS HEAVIER SNOW
   OVERSPREADS THIS REGION.
   
   ..GRAMS.. 12/20/2009
   
   
   ...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...BOX...OKX...ALY...PHI...
   
   LAT...LON   41757040 41277122 40517312 40307364 38927489 39137558
               39747596 40647533 41517433 42147307 42287187 42067084
               41757040