MESOSCALE DISCUSSION 0045 NWS STORM PREDICTION CENTER NORMAN OK 0328 AM CST TUE JAN 27 2015 AREAS AFFECTED...SERN NY...CT...RI...MA...SRN NH AND SERN ME CONCERNING...BLIZZARD VALID 270928Z - 271430Z SUMMARY...HEAVIEST SNOW BANDS WITH OCCASIONAL RATES OF 2+ INCHES PER HOUR WILL PERSIST THROUGH THE EARLY MORNING FROM ERN LONG ISLAND NWD THROUGH ERN CT...RI INTO PARTS OF CNTRL AND ERN MA. FARTHER NORTH SNOW WILL GRADUALLY INCREASE WITH OCCASIONAL 2+ INCHES PER HOUR RATES FROM SRN NH THROUGH ERN MAINE THROUGH 15Z. IMMEDIATELY SURROUNDING THE HEAVIEST BANDS...SNOWFALL RATES UP TO 1 INCH PER HOUR AT TIMES WILL PERSIST NEXT SEVERAL HOURS. DISCUSSION...AS OF 09Z THE HEAVIEST SNOW BANDS WITH RATES OF 2+ INCHES PER HOUR HAVE REORGANIZED FROM ERN LONG ISLAND NWD THROUGH ERN CT...RI INTO CNTRL/ERN MA AND SERN NH. THIS BAND OF SNOW IS ASSOCIATED WITH A ZONE OF LOW-MID LEVEL FRONTOGENETIC FORCING AND DEEP-LAYER ASCENT ALONG A N-S ORIENTED DEFORMATION AXIS. WV IMAGERY AND RAP ANALYSIS SHOW A COMPACT VORTICITY MAXIMUM JUST SOUTH OF LONG ISLAND SITUATED WITHIN THE LEFT EXIT REGION OF A STRONG UPPER JET OVER THE WRN ATLANTIC. AS THESE FEATURES CONTINUE NWD...ZONE OF STRONGEST ASCENT WILL GRADUALLY DEVELOP THROUGH SERN NEW ENGLAND INCLUDING SERN MAINE THROUGH THE EARLY MORNING. IN ADDITION TO HEAVY SNOW...THE NELY LLJ IS EXPECTED TO INCREASE TO 70+ KT OVER SERN NEW ENGLAND WITHIN GRADIENT ZONE BETWEEN THE NWD-MOVING OFFSHORE SFC LOW AND HIGH PRESSURE OVER SERN CANADA. SFC WINDS WILL CONTINUE TO GUST IN EXCESS OF 50 KT IN THIS REGION. AREA OF HIGHER REFLECTIVITY NEAR NANTUCKET APPEARS TO INDICATE A HEAVY WET SNOW AS A WARM NOSE ALOFT ADVECTS WWD ALONG THE INTENSE LLJ. SOME OF THIS SNOW MIGHT OCCASIONALLY MIX WITH SLEET FROM NANTUCKET ISLAND AND POSSIBLY NWD TO ERN CAPE COD...BUT THE PREDOMINANT PRECIPITATION TYPE WILL PROBABLY REMAIN SNOW. WEST OF THE HEAVY SNOW BAND FROM NRN NJ THROUGH NEW YORK CITY INTO WRN CT AND WRN MA...SNOWFALL RATES ARE EXPECTED TO REMAIN GENERALLY LESS THAN 1 INCH PER HOUR.
Posted on: Tue, 27 Jan 2015 10:47:04 +0000
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