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01/31/2011

TWO PART STORM STARTS LATE TONIGHT & LASTS THROUGH WEDNESDAY

THE GOOD NEWS IS THAT WE STARTED OFF THIS WORK WEEK ON A QUIET NOTE WEATHER WISE TODAY, AND DRY WEATHER WILL RETURN LATER THIS WEEK FOR THURSDAY AND FRIDAY.

THE BAD NEWS IS THAT WE'VE GOT SOME VERY MESSY WEATHER TO DEAL WITH IN BETWEEN. A TWO-PART STORM WILL AFFECT US THE NEXT COUPLE OF DAYS...THE SAME SYSTEM THAT WILL PRODUCE A WIDE SWATH OF PRECIP ALL THE WAY FROM THE ROCKIES AND PLAIN STATES THROUGH THE MIDWEST AND INTO THE MID-ATLANTIC AND NORTHEAST STATES. THE FIRST BATCH OF PRECIP WILL WILL COME OUT LATE TONIGHT AND LAST INTO TOMORROW. THE PRECIP WITH THIS FIRST PULSE WILL BE DRIVEN PRIMARILY FROM WARM ADVECTION, AND UPWARD MOTION DUE TO BEING IN THE RIGHT REAR QUADRANT OF AN EXITING JET STREAK THROUGH SOUTHEASTERN CANADA. THERE ARE ESSENTIALLY NO HEIGHT FALLS AND PVA WITH SYSTEM #1. FROM THE SOUTHERN QUARTER OF PA AND THE SOUTHERN THIRD OF NJ ON SOUTHWARD, SNOW AMOUNTS WITH THIS FIRST PIECE WILL BE ON THE LIGHT SIDE...GENERALLY AN INCH OR SO (EVEN LESS FARTHER SOUTH) FOLLOWED BY A BIT OF SLEET AND FREEZING RAIN.

THE FARTHER NORTH YOU GO, THE MORE SNOW THERE WILL BE WITH THIS FRONT END FEATURE. WHILE 2-4" AMOUNTS WILL BE COMMON ACROSS THE NORTHERN 2/3 OF PA, NORTHERN NJ, SOUTHERN NY, AND INTO NEW ENGLAND, A FEW SPOTS MAY PICK UP AS MUCH AS 5 OR 6 INCHES. AS THE SNOW IS CONTINUING INTO TOMORROW, WARMING WILL BE OCCURRING ALOFT, AND THE SNOW/SLEET LINE WILL MAKE SOME PROGRESS NORTHWARD. THEN, WE DO EXPECT A DISTINCT BREAK IN THE ACTION BETWEEN PART 1 AND PART 2. AT THE VERY LEAST, THE PRECIP WILL DWINDLE TO A BIT OF FREEZING DRIZZLE, FLURRIES, A FEW ICE PELLETS, ETC., DEPENDING ON WHERE YOU ARE IN THE NORTH TO SOUTH GRADIENT AREA.

IT IS POSSIBLE THAT THE PRECIP JUST TOTALLY SHUTS OFF FOR AWHILE, AS THE NAM IS SUGGESTING. THE BOTTOM LINE IS THAT THERE WILL BE A 6-9 HOUR PERIOD WITH NOT MUCH HAPPENING, BEFORE THE PRECIP RELOADS WITH ROUND #2.

THE PRECIP IN THAT SECOND BATCH DOES LOOK HEAVIER, MORE EXTENSIVE, AND OF LONGER DURATION THAT THE FIRST ROUND. THERE IS VERY LITTLE DOUBT THAT FROM ABOUT PITTSBURGH SOUTH AND WEST THIS WILL BE MAINLY RAIN. IT ALSO LOOKS LIKE A MAINLY RAIN EVENT FROM AROUND BALTIMORE AND WASHINGTON ON SOUTH AND EAST, AND SOMEWHAT UP THE COASTAL PLAIN TO THE JERSEY SHORE. MEANWHILE, ON THE OTHER SIDE OF THE COIN, YOU PROBABLY DON'T HAVE TO GO TOO FAR NORTH OF THE PA-NY BORDER, THE MIDDLE HUDSON VALLEY, AND THE CT-MA LINE TO GET INTO A ZONE WHERE MOST OR ALL OF THE PRECIP FALLS AS SNOW. ACCUMULATIONS UP NORTH WILL RAMP UP QUICKLY INTO A 6-12" AREA AND THEN A 12-18 STRIP.

 IN BETWEEN THE TWO EXTREMES, WE DO EXPECT A LOT OF ICE, WITH ALSO A LITTLE MORE SNOW FARTHER NORTH AND AN EVENTUAL CHANGEOVER TO PLAIN RAIN SOUTH OF A CERTAIN POINT. WE DO FEEL THAT THE FARTHER NORTH YOU GO, THE DEEPER THE COLD LAYER WILL BE AND THE BETTER THE CHANCE IS THAT THE PRECIP WILL FALL AS SLEET AS OPPOSED TO FREEZING RAIN. THERE WILL LIKELY BE A NARROW STRIP WHERE THE ICING IS REALLY BAD FROM SOMEWHERE IN CENTRAL OR SOUTHCENTRAL PA OVER TO THE LEHIGH VALLEY, INTO NJ, AND TOWARD THE NYC AREA.

THE PRECIP WILL COME TO AND END FROM WEST TO EAST WEDNESDAY AFTERNOON. WITH A SECONDARY LOW TAKING OVER, ANY WARMING AT THE SURFACE WILL BE CUT OFF AT THE PASS AT LEAST FROM I-80 NORTHWARD, AND PERHAPS FROM THE PA TURNPIKE NORTHWARD. FARTHER SOUTH, WE DO EXPECT A BRIEF SPIKE IN TEMPS BEFORE THE COLDER AIR MOVES BACK IN. THURSDAY AND FRIDAY DEFINITELY LOOK COLDER.

Posted by Lee Goldberg on January 31, 2011 | Permalink

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Comments

do you think the ice on tue night and wed will cause wide spread power outages.thank you

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