MESOSCALE DISCUSSION 0008
   NWS STORM PREDICTION CENTER NORMAN OK
   1046 AM CST FRI JAN 07 2011
   
   AREAS AFFECTED...PARTS OF THE LOWER HUDSON VALLEY / FAR SWRN MA / CT
   / LONG ISLAND
   
   CONCERNING...HEAVY SNOW 
   
   VALID 071646Z - 072045Z
   
   SWATH OF PRIMARILY MODERATE SNOWFALL RATES OVER NJ AND NYC METRO
   LATE THIS MORNING IS EXPECTED TO CONSOLIDATE IN A
   NARROW/INTENSIFYING BAND OF HEAVY SNOWFALL RATES EXCEEDING 1 INCH
   PER HOUR AS IT DEVELOPS NEAR THE LOWER HUDSON VALLEY VICINITY AND
   MOVES EWD ACROSS MOST OF CT BY EARLY EVENING.  
   
   RECENT SURFACE ANALYSIS PLACES A WELL-DEFINED TROUGH EXTENDING NW-SE
   FROM THE MOHAWK VALLEY TO NRN NJ.  A COLD FRONT EXTENDS SWD FROM NJ
   TO THE TIDEWATER VICINITY WHILE A RESIDUAL BAROCLINIC ZONE IS DRAPED
   ACROSS NEW ENGLAND.  A LOW LEVEL THETA-E RIDGE EXTENDS NWWD FROM 150
   MI S BID TO THE LOWER HUDSON VALLEY.  LONG LOOP OF WATER VAPOR
   IMAGERY AT 1630Z SHOWS A PV ANOMALY BEGINNING TO EJECT NEWD FROM
   NEAR THE MASON-DIXON LINE TOWARDS THE NYC METRO.  THIS IS EMBEDDED
   WITHIN A STRONG CYCLONIC FLOW REGIME PROVIDED BY LEFT EXIT REGION OF
   A 150 KT SPEED MAX OVER THE SRN APPALACHIANS/CAROLINAS.  AS THIS
   OCCURS...LARGE SCALE ASCENT PROVIDED BY UPPER SYNOPTIC FORCING WILL
   FAVORABLY JUXTAPOSE WITH THE PREVIOUSLY DESCRIBED LOW LEVEL THETA-E
   PLUME--THEREBY ALLOWING A GREATER UPWARD VERTICAL MOTION RESPONSE. 
   ADDITIONAL LOW LEVEL FRONTOGENETIC FORCING SHOULD LEND SUPPORT IN
   THE EVENTUAL NARROWING/INTENSIFICATION OF SHALLOW CONVECTION.
   
   SUITE OF LATEST CONVECTIVE ALLOWING MODELS REINFORCES THE IDEA OF A
   BAND OF SNOW DEVELOPING BY THE 18-20Z TIMEFRAME AND MOVING W TO E
   ACROSS MUCH OF CT THROUGH 00Z.  THIS BAND WILL PROBABLY LEAD TO A
   QUICK BURST OF HEAVY SNOWFALL RATES EXCEEDING 1 INCH/HR FOR A FEW
   HOURS.  FARTHER S OVER LONG ISLAND...ALTHOUGH TEMPS HAVE WARMED INTO
   THE MID-UPPER 30S IN PLACES...COLD PROFILE ALOFT WILL PROBABLY
   SUPPORT PRIMARILY WET SNOW /PERHAPS BRIEF INTERMITTENT LIGHT
   RAIN/...ESPECIALLY DURING THE HEAVIEST PRECIP RATES.
   
   ..SMITH.. 01/07/2011
   
   
   ATTN...WFO...BOX...OKX...ALY...
   
   LAT...LON   40607362 42187379 42457360 42477330 41917222 41197166
               40787262 40607362