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Mesoscale Discussion 101
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   MESOSCALE DISCUSSION 0101
   NWS STORM PREDICTION CENTER NORMAN OK
   1223 PM CST THU FEB 13 2014

   AREAS AFFECTED...PORTIONS OF ERN NY...SRN VT...CNTRL/SRN
   NH...CNTRL/WRN MA...CT...COASTAL SRN MAINE

   CONCERNING...HEAVY SNOW 

   VALID 131823Z - 132330Z

   SUMMARY...HEAVY SNOW WITH RATES OF 1-3 INCHES/HOUR -- LOCALLY 
   HIGHER -- WILL CONTINUE TO SHIFT NEWD ACROSS PARTS OF ERN NY AND NEW
   ENGLAND INTO THE LATE AFTERNOON.

   DISCUSSION...SFC OBSERVATIONS AND MOSAIC RADAR IMAGERY SUGGEST A
   SOLID SHIELD OF HEAVY SNOW ARCING ENE FROM NERN PA INTO SRN NEW
   ENGLAND. THIS ACTIVITY IS BEING SUPPORTED BY VERY STRONG DEEP ASCENT
   AIDED BY INTENSE WARM ADVECTION SUPPLIED BY A STRONG LLJ -- E.G.
   65-KT ELY/S AT 1.5-KM AGL SAMPLED BY OKX VWP. SFC PRESSURE FALLS OF
   6-8 MB PER 2 HOURS HAVE BEEN NOTED OFF THE LONG ISLAND AND CT COAST
   IN ASSOCIATION WITH THE WARM ADVECTION. THE NEWD TRANSLATION OF
   RELATED DEEP FRONTOGENETIC CIRCULATIONS BENEATH STRONG UPPER
   DIVERGENCE OFFERED BY A COUPLED JET STRUCTURE WILL SUPPORT THE NEWD
   TRANSLATION OF HEAVY SNOW. THROUGH THE LATE AFTERNOON HOURS...THE
   HEAVIEST SNOW -- WITH RATES OF 2-3 INCHES PER HOUR AND LOCALLY
   HIGHER -- WILL LIKELY SHIFT NEWD ACROSS PARTS OF CNTRL/WRN MA...SERN
   VT...SRN NH...AND COASTAL SRN MAINE WHERE THE ELEVATED INFLUX OF
   OCEAN-MODIFIED TRAJECTORIES WILL CONTRIBUTE TO HIGHER PW ALONG WITH
   MEAGER ELEVATED BUOYANCY. AN ISOLATED LIGHTNING STRIKE OR TWO MAY
   ACCOMPANY THE HIGHEST SNOWFALL RATES.

   ON A TEMPORARY BASIS...WEAKENING MID-LEVEL ASCENT AND THE INFLUX OF
   A MID-LEVEL DRY SLOT PER WATER VAPOR LOOPS ARE CONTRIBUTING TO A
   DECREASE IN SNOW RATES IN THE WAKE OF THE HEAVIEST SNOW -- I.E.
   ACROSS PORTIONS OF SERN NY AND NRN NJ. A SIMILAR DECREASE IN
   SNOWFALL RATES WILL EXTEND NEWD INTO SRN NEW ENGLAND INTO THE LATE
   AFTERNOON. HOWEVER...WITH SUFFICIENT LOW-LEVEL ASCENT LINGERING IN
   THESE AREAS FOR MORE SHALLOW PRECIPITATION GENERATION...LIGHT
   FREEZING RAIN/DRIZZLE AND PERHAPS LIGHT SNOW GRAINS WILL REMAIN A
   CONCERN IN THE WAKE OF THE HEAVIER SNOW. FREEZING RAIN RATES OF
   0.01-0.03 INCH/HOUR WILL BE POSSIBLE. PRECIPITATION MAY CHANGE TO
   LIQUID RAIN WHERE SFC TEMPERATURES REMAIN ABOVE 32F...SIMILAR TO
   CURRENT CONDITIONS AROUND PARTS OF THE NYC METRO AND LONG ISLAND. A
   RENEWED POTENTIAL FOR HEAVIER WINTER PRECIPITATION WILL EXIST DURING
   THE EVENING AS A MID-LEVEL VORT MAX CURRENTLY OVER THE NC/VA
   PIEDMONT AFFECTS THE AREA.

   ..COHEN.. 02/13/2014


   ATTN...WFO...GYX...BOX...BTV...OKX...ALY...BGM...

   LAT...LON   41867471 43177400 43917245 44157117 43557026 42997071
               42097166 41307303 41007390 41867471 

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Page last modified: March 20, 2014
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