MESOSCALE DISCUSSION 0113
   NWS STORM PREDICTION CENTER NORMAN OK
   0955 AM CST SAT FEB 02 2013
   
   AREAS AFFECTED...JEFFERSON COUNTY NY INCLUDING THE WATERTOWN AREA
   
   CONCERNING...HEAVY SNOW 
   
   VALID 021555Z - 022200Z
   
   SUMMARY...SNOW RATES OF 2 IN/HR ARE ANTICIPATED IN A LAKE EFFECT
   SNOW BAND OVER JEFFERSON COUNTY NY THROUGH THE AFTERNOON...AFFECTING
   THE WATERTOWN AREA.
   
   DISCUSSION...BUF/TYX 0.5-DEGREE REFLECTIVITY DATA DEPICT A SHALLOW
   REFLECTIVITY BAND BECOMING BETTER DEFINED OVER LAKE
   ONTARIO...ORIENTED WSW-ENE. THIS BAND REPRESENTS A WAVY LAKE EFFECT
   HEAVY SNOW BAND THAT EXTENDS DOWNWIND OF THE LAKESHORE INTO
   JEFFERSON COUNTY NY...AND RECENT WATERTOWN OBS INDICATE MODERATE TO
   HEAVY SNOW ONGOING. MESOSCALE ASCENT SUPPORTING THIS BAND EMANATES
   FROM /1/ THE RELATIVELY LONG OVER-LAKE FETCH LENGTH CONTRIBUTING TO
   MODESTLY DEEP CONVECTIVE BOUNDARY LAYERS -- REACHING 7-9 KFT PER
   FORECAST SOUNDINGS -- AND /2/ WARM ADVECTION IN ADVANCE OF A
   MID-LEVEL SHORTWAVE TROUGH MANIFESTED IN A WEAKLY VERTICALLY VEERING
   WIND PROFILE WITHIN THE LOWEST 1.5 KM AGL PER BUF VWP. THE
   ISALLOBARIC RESPONSE TO PRESSURE FALLS DRIVEN BY THE WARM ADVECTION
   WILL YIELD A TENDENCY FOR THE SNOW BAND TO GRADUALLY SHIFT NWD
   TOWARD THE ST. LAWRENCE RIVER THROUGH MID-AFTERNOON.
   THEREAFTER...SLIGHT LOW-LEVEL VEERING SHOULD PROMOTE A SWD
   PROGRESSION OF THE BAND BY LATE THIS AFTERNOON. THESE
   CHARACTERISTICS ARE ILLUSTRATED BY THE CONSENSUS AMONGST
   HIGH-RESOLUTION WRF GUIDANCE...WHICH SUGGESTS THAT 2-IN/HR SNOW
   RATES WILL BE LIKELY...MAINLY IMPACTING JEFFERSON COUNTY.
   
   ..COHEN/CARBIN.. 02/02/2013
   
   
   ATTN...WFO...BUF...
   
   LAT...LON   44097630 44187614 44177592 44077577 43897582 43767593
               43737615 43827631 44097630