MESOSCALE DISCUSSION 0029
   NWS STORM PREDICTION CENTER NORMAN OK
   1129 PM CST MON JAN 17 2011
   
   AREAS AFFECTED...LOWER DELAWARE RIVER VALLEY...SERN PA
   
   CONCERNING...FREEZING RAIN 
   
   VALID 180529Z - 181130Z
   
   PRECIPITATION RATES ARE EXPECTED TO INCREASE AFTER 06Z ACROSS SERN
   PA AND THE LOWER DELAWARE RIVER VALLEY...INCLUDING THE PHILADELPHIA
   METRO AREA. P-TYPE WILL TRANSITION FROM SNOW TO FZRA BY EARLY
   MORNING...WITH LIQUID PRECIPITATION RATES OF 0.05-0.10 IN/HR.
   
   A SWATH OF WINTRY-MIXED PRECIPITATION OVER DELMARVA WILL CONTINUE
   EXPANDING NWD INTO THE LOWER DELAWARE RIVER VALLEY AND SERN PA. 05Z
   SFC OBJECTIVE ANALYSIS INDICATES THE SFC FREEZING LINE IS POSITIONED
   FROM 15 NE ACY TO 30 SSW DOV...WITH LIGHT-MODERATE SNOW ALREADY
   BEING OBSERVED OVER MUCH OF NJ AND SERN PA. AN EVENTUAL TRANSITION
   TO FZRA IS EXPECTED TO OCCUR BY 06Z AS LOW-LEVEL WAA STRENGTHENS
   ATOP SUB-FREEZING SFC TEMPERATURES. STRONG ISENTROPIC ASCENT WITH
   40-50 KT LOW-LEVEL WINDS WILL YIELD INCREASING PRECIPITATION RATES
   OVER THE AREA. WITH TIME...THE SFC FREEZING LINE IS EXPECTED TO
   SHIFT SLIGHTLY NWD...WITH A TRANSITION TO RAIN FORECAST TO OCCUR
   OVER NJ...NRN DEL...AND PORTIONS OF SERN PA BY 12Z.
   
   ..ROGERS.. 01/18/2011
   
   
   ATTN...WFO...PHI...CTP...LWX...
   
   LAT...LON   39687511 39507572 39517621 39667688 39957734 40497690
               40967560 40977504 40717457 40207444 39687511