MESOSCALE DISCUSSION 0041
   NWS STORM PREDICTION CENTER NORMAN OK
   0632 AM CST FRI JAN 21 2011
   
   AREAS AFFECTED...PORTIONS NERN MA...SERN NH...SRN MAINE.
   
   CONCERNING...HEAVY SNOW 
   
   VALID 211232Z - 211800Z
   
   ALTHOUGH HEAVIEST PRECIP SHOULD SHIFT FROM SERN MA ACROSS GULF OF
   MAINE THROUGH AT LEAST 16Z...NWRN PORTION OF PRECIP PLUME MAY
   PRODUCE 1-2 INCH/HOUR SNOW RATES AS IT SHIFTS NEWD OVER DISCUSSION
   AREA...MAINLY NEAR AND SE OF I-95.  ZONE OF HEAVIEST PRECIP THEN MAY
   MAKE LANDFALL ACROSS DOWN-EAST MAINE AFTER ABOUT 17Z...BRINGING
   POTENTIAL FOR CONVECTIVE SNOW BURSTS WITH LOCALLY HIGHER RATES. 
   BRIEF SNOW-RAIN TRANSITION MAY OCCUR ALONG IMMEDIATE DOWN-EAST COAST
   IN 18-19Z TIME FRAME AS WAA FORCES NEAR-SFC TEMPS ABOVE FREEZING
   TEMPORARILY...PRIOR TO CAA AND REDUCTION IN PRECIP THAT SHOULD
   FOLLOW CYCLONE PASSAGE.  SNOW SHOULD REMAIN PREDOMINANT PRECIP MODE
   ANY APPRECIABLE DISTANCE INLAND.
   
   12Z SFC ANALYSIS SHOWS ELONGATED SFC LOW OVER CENTRAL/SWRN LONG
   ISLAND.  CYCLONE IS FCST TO STRENGTHEN AND CONSOLIDATE AS IT CROSSES
   CAPE COD DURING 14-15Z TIME RANGE.  LOW THEN SHOULD DEEPEN FURTHER
   OVER WATERS OFFSHORE MAINE WITH APCH OF STG MID-UPPER SHORTWAVE
   TROUGH NOW EVIDENT IN MOISTURE CHANNEL IMAGERY OVER WRN PORTIONS
   NY/PA.  AS THIS OCCURS...ELEVATED LOW-LEVEL WAA CONVEYOR SHOULD
   BECOME MORE INTENSE AROUND ITS NRN SEMICIRCLE.  RELATED LLJ --
   POTENTIALLY REACHING 850-MB SPEEDS OF 60-70 KT OFFSHORE -- WILL
   TRANSPORT INCREASING MOISTURE INTO LOWER PORTIONS OF STG 750-850 MB
   LAYER FRONTOGENETIC FORCING REGIME THAT IS FCST TO SHIFT NEWD OVER
   COASTAL MAINE.  ERN PORTION OF FRONTOGENESIS MAX WILL BE JUXTAPOSED
   WITH NOSE OF STRONGEST LLJ SEGMENT...AND AS SUCH...MOST INTENSE ZONE
   OF 285-291 K ISENTROPIC ASCENT...BASED ON RUC PROGS THAT VERIFY WELL
   WITH RESPECT TO CURRENT POSITION OF STRONGEST PRECIP AND LOW-LEVEL
   LIFT.  UPPER PORTION OF ZONE OF STRONGEST UVV ALSO SHOULD REACH INTO
   IDEAL DENDRITIC GROWTH LAYER...BASED ON FCST SOUNDINGS THAT RESEMBLE
   12Z CHH RAOB BUT WITH SUBFREEZING BOUNDARY LAYER AND SOMEWHAT COOLER
   MID-UPPER TEMPS.
   
   ..EDWARDS.. 01/21/2011
   
   
   ATTN...WFO...CAR...GYX...BOX...
   
   LAT...LON   41917053 42177139 42837133 43417101 44237031 44866940
               45196848 45296742 45156737 45196718 44976704 44806694
               44606730 44616747 44446754 44546766 44336807 44456835
               44236826 44086836 44206862 44016859 43996866 44036885
               44116892 44186896 44026906 43926925 43856950 43716980
               43746997 43587018 43407039 43287056 43167057 43097061
               42887083 42637075 42707060 42567059 42347100 42247075
               41987068 41917053