MESOSCALE DISCUSSION 0123
   NWS STORM PREDICTION CENTER NORMAN OK
   1150 AM CST FRI FEB 08 2013
   
   AREAS AFFECTED...NRN NJ...SERN NY THROUGH SRN NEW ENGLAND
   
   CONCERNING...HEAVY SNOW 
   
   VALID 081750Z - 082145Z
   
   SUMMARY...SNOW WILL CONTINUE TO EXPAND NWD FROM NRN NJ AND SERN NY
   THROUGH SRN NEW ENGLAND. SNOWFALL INTENSITY WILL GRADUALLY INCREASE
   THROUGH THE DAY WITH RATES APPROACHING 1 INCH PER HOUR BY LATE
   AFTERNOON OR EARLY EVENING. HEAVIEST RATES /2+ INCH PER HOUR/ ARE
   EXPECTED TO EVOLVE DURING THE EVENING.
   
   DISCUSSION...EARLY THIS AFTERNOON A DEEP SURFACE LOW WAS LOCATED
   JUST OFF THE MID ATLANTIC COAST WITH A WARM FRONT EXTENDING EWD FROM
   THE LOW INTO THE WESTERN ATLANTIC. THIS AREA OF LOW PRESSURE HAS
   DEVELOPED IN ASSOCIATION WITH A VORT MAX NEAR THE CNTRL VA COAST AND
   WITHIN A COUPLED UPPER JET STRUCTURE. AN EXPANSIVE AREA OF
   PRECIPITATION IS IN PROGRESS FROM NJ INTO SRN NEW ENGLAND WITHIN
   ZONE OF ISENTROPIC ASCENT NORTH OF WARM FRONT. SNOW RATES WITHIN
   THIS AREA SHOULD GENERALLY REMAIN AOB 0.5 INCH PER HOUR THROUGH MID
   AFTERNOON. PRECIPITATION MOSTLY IN THE FORM OF RAIN OVER LONG ISLAND
   SHOULD TRANSITION TO SNOW DURING THE EVENING AS THE WARM NOSE AOB
   850 MB BEGINS TO COOL WITH THE ONSET OF COLD ADVECTION NW OF THE LOW
   CENTER.
   
   LATEST OBJECTIVE ANALYSIS INDICATES A ZONE OF STRONG 850-700 MB
   FRONTOGENETIC FORCING WITHIN DEFORMATION AXIS JUST NE OF THE LOW
   CENTER OFF THE SRN NJ COAST. THIS ZONE OF STRONG FORCING AND MID
   LEVEL ASCENT WILL DEVELOP NWD THROUGH TODAY AS THE LEAD IMPULSE
   INTERACTS WITH UPSTREAM TROUGH OVER THE GREAT LAKES AND EJECTS
   TOWARD SRN NEW ENGLAND. THEREFORE...SNOWFALL RATES WILL UNDERGO A
   SUBSTANTIAL INCREASE FROM NRN NJ INTO SRN NEW ENGLAND BY EARLY
   EVENING AS ZONE OF ASCENT DEVELOPS NWD AND DEEPENS THROUGH THE
   DENDRITIC GROWTH LAYER. THE SNOW SHOULD EVENTUALLY DEVELOP BANDED
   STRUCTURES THIS EVENING WITHIN THE NWD DEVELOPING FRONTOGENETIC
   ZONE...AND THERE IS ALSO SOME INDICATION THAT THERE COULD BE SOME
   SLANTWISE CONVECTIVE ENHANCEMENT WITHIN THE BANDS.
   
   ..DIAL.. 02/08/2013
   
   
   ATTN...WFO...BOX...OKX...ALY...PHI...
   
   LAT...LON   40807257 40387431 40557502 41387456 42317291 42637071
               41777008 41297097 40807257