MESOSCALE DISCUSSION 2612 NWS STORM PREDICTION CENTER NORMAN OK 1123 AM CST SUN DEC 14 2003 AREAS AFFECTED...PORTIONS NRN NJ...ERN AND COASTAL NY...CT...MA...VT...NH...RI CONCERNING...HEAVY SNOW AND SLEET VALID 141723Z - 142145Z CORRECTED FOR HEADER/TEXT TYPOS PARALLEL AREAS OF HEAVY SNOW AND SNOW CHANGING TO SLEET SHOULD SPREAD NEWD ACROSS DISCUSSION AREA THROUGH AT LEAST 21Z. SNOW SHOULD CHANGE TO RAIN NEAR COAST FROM SRN/ERN LONG ISLAND TO CAPE COD...WITH SLEET JUST N OF NWD-DRIFTING FREEZING LINE OVER PORTIONS SERN NY AND SRN NEW ENGLAND. HEAVY SNOW WITH RATES NEAR 2 INCHES/HOUR...LOCALLY HIGHER -- EXPECTED FARTHER N AND NW. LOW ANALYZED AT 16Z INVOF COASTAL NC/VA BORDER IS FCST TO MOVE NEWD THIS AFTERNOON...FOLLOWING ISALLOBARIC FALL AXIS AND WEAK/CO-LOCATED SFC TROUGH ANALYZED OVER COASTAL DELMARVA/SRN NJ. AS DEEPENING CYCLONE APPROACHES THERE WILL BE PRONOUNCED INCREASES IN LOW LEVEL FRONTOGENESIS...ALONG WITH WAA/ISENTROPIC ASCENT...ABOVE BOUNDARY LAYER. RAPID INCREASE IN LOW LEVEL FORCING APPEARS WELL PROGGED BY RUC ASCENT FCST IN 285-288 K ISENTROPIC LAYER. ASSOCIATED WARMING ALONG COAST FROM LONG ISLAND TO CAPE COD MAY 1. LIFT FREEZING LINE NWWD INTO PORTIONS LONG ISLAND...SRN RI AND SERN MA NEAR A LGA-PYM LINE BY 21Z...CAUSING SNOW TO CHANGE TO RAIN E OF THAT LINE. 2. WARM 700-900 MB LAYER ENOUGH -- JUST N OF SFC FREEZING LINE -- TO MELT SNOW GENERATED AT HIGHER LEVELS. THAT PRECIP THEN WOULD FREEZE AGAIN JUST ABOVE SFC TO FORM SLEET AS SUGGESTED BY THERMODYNAMIC STRATIFICATION OF MODIFIED OKX RAOB AND RUC SOUNDINGS. ATTM EXPECT RESULTING SLOW-SLEET TRANSITION AS FAR INLAND AS NEAR POU-ORH-BOS LINE. STILL FARTHER INLAND...INCREASINGLY HEAVY SNOW IS EXPECTED WITH 2-3 INCH/HOUR RATES BECOMING COMMON FROM ALB-UCA CORRIDOR ENEWD AND NEWD WITH TIME...ACROSS ADIRONDACKS AND NRN MA...NRN HUDSON/CHAMPLAIN/NRN CT RIVER VALLEYS...AND ADJOINING WHITE/GREEN MTNS OF VT/NH. ..EDWARDS.. 12/14/2003 ATTN...WFO...BOX...OKX...GYX...BTV...ALY...BGM...BUF... 40687403 41237280 41937098 42067006 41506987 41117023 40567344 40597399 44607390 44407244 44097149 43317111 42697081 42407101 42427226 42407358 41887476 42367539 43187533 44187500
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