MESOSCALE DISCUSSION 0268
   NWS STORM PREDICTION CENTER NORMAN OK
   1158 AM CDT THU MAR 24 2011
   
   AREAS AFFECTED...SIERRAS OF ERN CA AND EXTREME W-CNTRL NV
   
   CONCERNING...HEAVY SNOW 
   
   VALID 241658Z - 242100Z
   
   SNOWFALL RATES OF 2 IN/HR ARE EXPECTED TO DEVELOP OVER THE SIERRAS
   OF ERN CA AND FAR W-CNTRL NV THIS AFTERNOON AND CONTINUE INTO THIS
   EVENING.
   
   DEEP-LAYER LOW PRESSURE CENTERED OFF THE COAST OF CA/ORE WILL SHIFT
   EWD THIS AFTERNOON INTO TONIGHT. RUC ANALYSIS AND SATELLITE-DERIVED
   WINDS DEPICT A CORE OF STRONG DEEP-LAYER FLOW WITHIN THE SRN
   SEMICIRCLE OF THE LOW /500-MB WIND SPEEDS OF 70 TO 80 KT AND 700-MB
   WIND SPEEDS OF 50 TO 60 KT/ APPROACHING THE COAST OF NRN CA. AS
   STRONG SWLY TO WLY LOW/MID-LEVEL FLOW IMPINGES ON THE SIERRAS AND
   INTERACTS WITH A PLUME OF DEEP-LAYER PACIFIC MOISTURE WRAPPING
   AROUND THE LOW...SNOWFALL RATES OF 2 IN/HR ARE EXPECTED TO DEVELOP
   OVER THE NRN SIERRAS EARLY THIS AFTERNOON /ACCORDING TO 09Z SREF
   GUIDANCE AND RECENT RUNS OF THE EXPERIMENTAL HRRR/. THIS WILL OCCUR
   DUE TO SUBFREEZING TEMPERATURES THROUGHOUT THE TROPOSPHERE. LOCALLY
   HIGHER RATES WILL BE POSSIBLE WITHIN A BAND OF HEAVIER SNOW
   ASSOCIATED WITH A SEWD-MOVING COLD FRONT. THE SNOW IS EXPECTED TO
   PERSIST FOR MUCH OF THE AFTERNOON INTO THIS EVENING. HOWEVER...THE
   PRIMARY FOCUS FOR HIGHER RATES WILL GRADUALLY SHIFT SWD WITH
   TIME...AS THE CORE OF STRONGEST LOW/MID-LEVEL FLOW SINKS SWD.
   
   ..COHEN.. 03/24/2011
   
   
   ATTN...WFO...VEF...REV...HNX...STO...
   
   LAT...LON   38422038 39352096 39972157 40512181 40812169 40022062
               39111982 37661878 36981841 36291821 35981831 36011854
               36251874 36701907 37141934 38422038