MESOSCALE DISCUSSION 0019
   NWS STORM PREDICTION CENTER NORMAN OK
   0700 PM CST TUE JAN 11 2011
   
   AREAS AFFECTED...ERN PA...NJ...SERN NY AND SRN CT
   
   CONCERNING...HEAVY SNOW 
   
   VALID 120100Z - 120600Z
   
   SNOWFALL RATES WILL GRADUALLY INCREASE THROUGH EVENING INTO THE
   EARLY MORNING FROM ERN PA AND NJ THROUGH SERN NY AND SRN CT. RATES
   LOCALLY GREATER THAN 1 INCH PER HOUR WILL BECOME POSSIBLE AFTER 03Z.
   
   
   THIS EVENING A STRONG 150+ KT UPPER JET WAS MOVING EWD THROUGH BASE
   OF TROUGH LOCATED OVER THE OH VALLEY. AGEOSTROPHIC FORCING WITHIN
   EXIT REGION OF THIS FEATURE WILL OVERTAKE BAROCLINIC ZONE OFF THE
   MID ATLANTIC SEABOARD...RESULTING IN DEEPENING OF SURFACE LOW OFF
   THE VA COAST AS IT LIFTS NWD OVERNIGHT. THE DEEPENING SURFACE LOW
   WILL BE ACCOMPANIED BY AN INCREASE IN FRONTOGENETIC FORCING AND A
   STRENGTHENING LLJ WHICH WILL AUGMENT ISENTROPIC LIFT FROM THE MID
   ATLANTIC SEABOARD NWD INTO SRN NEW ENGLAND TONIGHT. TRENDS ALREADY
   INDICATE SNOW EXPANDING IN COVERAGE FROM ERN PA INTO NJ. THE SNOW
   WILL LIKELY BECOME ORGANIZED AS BANDS LATER THIS EVENING AND
   TONIGHT. STEEPER MID-LEVEL LAPSE RATES WITHIN UPPER JET EXIT REGION
   WILL RESULT IN CONVECTIVE ENHANCEMENT WITH SOME LIGHTNING ACTIVITY
   ALSO POSSIBLE. A DEEP SUBFREEZING LAYER WHERE TEMPERATURES ARE
   MOSTLY AOA -5C WILL EXIST BENEATH THE DEVELOPING UNSTABLE LAYER
   WHICH COULD SERVE TO FURTHER AUGMENT SNOWFLAKE GROWTH THROUGH
   AGGREGATION. RATES WILL LIKELY LOCALLY EXCEED 1 INCH PER HOUR AT
   TIMES...ESPECIALLY WITHIN CONVECTIVE ELEMENTS.
   
   ..DIAL.. 01/12/2011
   
   
   ATTN...WFO...OKX...ALY...PHI...BGM...
   
   LAT...LON   40927241 40527370 39307458 39727540 41147512 41717379
               41427226 40927241