NYC NWS forecasts explosive development
Posted by JAC on 1/25/2011, 1:45 pm
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE NEW YORK NY
104 PM EST TUE JAN 25 2011

.NEAR TERM /THROUGH TONIGHT/...
HAVE UPGRADED ENTIRE AREA TO A WINTER STORM WATCH FOR WEDNESDAY
AFTERNOON INTO WEDNESDAY NIGHT. BASED ON 12Z MODEL SUITE...MODELS
CONVERGING ON EXPLOSIVE DEVELOPMENT OF LOW PRESSURE AS IT TRACKS
NE FROM THE CAROLINAS WEDNESDAY AFTERNOON AND THEN OVER THE 40/70
BENCHMARK WEDNESDAY NIGHT. DUE TO THE IMMENSE AMOUNT OF CONVECTION
WITH THIS DEVELOPING LOW OVER THE GULF THIS AFTERNOON THERE IS
SOME UNCERTAINTY IN THE MODELS HANDLING OF THE TRACK OF THIS
SYSTEM. BUT BASED ON QPF/LIFT POTENTIAL AND EXPECTED THERMAL
FIELDS BELIEVE WATCH IS WARRANTED AT THIS TIME.

.SHORT TERM /WEDNESDAY THROUGH THURSDAY/...
AS HIGH PRES RETREATS TO THE N ON WED...A COASTAL STORM WILL TAKE
SHAPE OFF THE NORTH CAROLINA COAST. MODELS ARE IN DECENT AGREEMENT
THAT IT TRACKS NE OVER OR JUST OUTSIDE THE 40N 70W BENCHMARK AND
THEN INTO THE NORTHERN ATLANTIC. THIS TRACK NORMALLY MEANS AN ALL
SNOW EVENT FOR THE MAJORITY OF THE AREA...HOWEVER SOME OF THE
GUIDANCE IS INDICATING WARMING ALOFT WITH A MIX/CHANGEOVER AT THE
COAST. THE SREF IS THE WARMEST AND WAS DISREGARDED. THE NAM KEEPS
THE WHOLE EVENT SNOW ACROSS THE ENTIRE CWA...WHILE THE GFS DOES
INDICATE ABOUT A 6 HOUR PERIOD OF SN/PL/RA MIX IN NJ/NYC/LI...POSSIBLY
COASTAL CT.

SINCE CONFIDENCE OF REACHING 6 INCHES OF SNOW...IS AT LEAST 50
PERCENT ACROSS INTERIOR SOUTHERN CT...MOST OF THE LOWER HUDSON
COUNTY AND WESTERN PASSAIC...HAVE ISSUED A WINTER STORM WATCH FOR
THESE AREAS. THIS MAY NEED TO BE EXTENDED FURTHER SOUTH LATER
TODAY...BUT THE DURATION AND TIMING OF THE MIXED PRECIP IS WHAT IS
TROUBLING. TOTAL QPF IS ALSO STILL UNCERTAIN...SEE HYDRO SECTION
FOR DETAILS.

WAA PRECIP SHOULD RUSH IN FROM THE SOUTH BY EARLY AFTERNOON WED.
PRECIP IS EXPECTED TO BEGIN AS LIGHT SNOW EVERYWHERE...THEN THE
BEST TIMING FOR THE MIX IS BETWEEN 7PM AND 1AM. EVENING RUSH ON
WED AND THU MORNING COULD BE TREACHEROUS. COLD AIR RUSHES BACK IN
ON A N-NW FLOW AS THE STORM DEPARTS CHANGING THE PRECIP BACK TO
ALL SNOW ACROSS THE ENTIRE CWA. IT APPEARS THAT IF WARNING
CRITERIA WILL BE MET AT THE COAST...IT WILL BE ON THE BACK SIDE OF
THE STORM WHEN THE HEAVIEST PRECIP IS EXPECT TO OCCUR...AGAIN
BETWEEN 7PM AND 1AM...BUT THIS WILL BE DEPENDENT ON THE TIMING OF
THE CHANGEOVER BACK TO SNOW.

FORECAST IS LOW TO MODERATE AT THIS TIME.

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Thursday 1/27 System - JAC, 1/24/2011, 7:32 am
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