Morning NWS Discussions
Posted by JAC on 1/24/2011, 7:37 am
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE TAUNTON MA
437 AM EST MON JAN 24 2011

WHAT IS CERTAIN IS A CLOSED LOW SYS IN THE NERN GULF 0Z WED WILL
SIMULTANEOUSLY DEEPEN AND LIFT NWD INTO THE OUTER BANKS BY 18Z WED
AND ACRS THE BENCHMARK AROUND 6Z THURS. THE COMBINATION OF STRONG
UPR LVL DIV AIDED BY A COUPLING OF LEFT EXIT/RIGHT ENTRANCE RGNS OF
H3 JET AXES...STRONG ISENTROPIC LIFT OF WARM AND MOIST AIR...COUPLED
SFC AND UPR LVL JET AXES LENDING TO STRONG AGEO VERTICAL CIRC...AND
CONSEQUENTIAL TROWAL STRUCTURE PARENTED WITH MID-LVL FRONTOGENESIS
SHOULD LEND TO A VERY IMPRESSIVE AND DEEP COASTAL STORM SYSTEM. IT
IS EXPECTED THAT AN INITIAL STRATIFORM PRECIP SHIELD WILL OVERSPREAD
THE RGN WITH A LATER AREA OF FAVORABLE HEAVIER PRECIP DVLPMNT ALONG
THE NW QUADRANT OF THE ATTENDANT SFC LOW AS IT PASSES SOUTH OF THE
NEW ENG COASTLINE. LATEST TRENDS HIGHLIGHT THIS AREA OF HEAVIER PRECIP
DVLPMNT TO COME ASHORE BUT TO REMAIN MORESO IN THE WARM SECTOR OF
THE STORM.

SOME FINAL CONCERNS FOCUS UPON THE FACT OF HOW DEEP THIS SYS WILL
BECOME RESULTING IN VERY STRONG AND GUSTY WINDS...ESPECIALLY FOR
MARINE AREAS. THERE IS SOME FORETHOUGH TO THE POSSIBILITY FOR
COASTAL FLOODING...BUT WILL FOCUS ON THIS DETAIL AS A BETTER HANDLE
ON THE FCST IS OBTAINED.





AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE NEW YORK NY
630 AM EST MON JAN 24 2011

.LONG TERM /TUESDAY NIGHT THROUGH SUNDAY/...
MEDIUM RANGE MODEL GUIDANCE IS COMING INTO FOCUS RE THE
COASTAL STORM PROGGED TO IMPACT THE AREA TUE NIGHT INTO THU...AS A
VIGOROUS SRN STREAM SHORTWAVE TRAVERSING THE DEEP SOUTH BECOMES
NEGATIVELY TILTED AND MOVES NE UP THE SOUTHEAST AND MID ATLANTIC
COASTS. USED A BLEND OF THE 00Z GFS AND 23/12Z ECWMF FOR THIS
FORECAST...WITH ASSOCIATED PRIMARY SFC LOW PRESSURE ALONG THE NE
GULF COAST REDEVELOPING ALONG A LOW LEVEL BAROCLINIC ZONE ALONG THE
CAROLINA COASTS TUE NIGHT INTO WED...THEN MOVING OFF THE SRN MID
ATLANTIC COAST WED NIGHT AND PASS JUST SE OF LONG ISLAND LATE WED
NIGHT INTO EARLY THU MORNING.

PRECIP SHOULD BEGIN LATE TUE NIGHT OR EARLY WED MORNING...BEGINNING
AS SNOW...BUT THEN TRANSITIONING TO PRIMARILY RAIN AT THE COAST AND
A WINTRY MIX INLAND AS WARMER AIR STARTS TO WORK IN ALOFT...WITH TOP
DOWN PARTIAL THICKNESS P-TYPE ALGORITHMS IN GENERAL AGREEMENT.
ANY ACCUMULATIONS DURING THE DAY ON WED LOOK TO BE MINOR AND
CONFINED MORE TO THE INTERIOR...ESPECIALLY THE HIGHER ELEVATIONS.

THE HEAVIEST PRECIP SHOULD OCCUR WED NIGHT...MAINLY VIA STRONG
ISENTROPIC LIFT ACROSS EASTERN SECTIONS AS A 50-60 KT EASTERLY LLJ
OVERRIDES A WARM FRONTAL BOUNDARY EXTENDING NE FROM THE SFC LOW
TOWARD CAPE COD AND THE ISLANDS...AND VIA FRONTOGENETICALLY FORCED
BANDING ACROSS WESTERN SECTIONS WELL NW OF THE SFC LOW.
MEANWHILE...LOW LEVEL FLOW SHOULD STRENGTHEN AND BACK NE-N AS THE
SFC LOW APPROACHES...WITH SFC TEMPS DROPPING BELOW FREEZING AND
ALLOWING PRECIP TO TRANSITION BACK TO SNOW...WITH AT LEAST A
TRANSITIONAL PERIOD OF FREEZING RAIN POSSIBLE ACROSS MOST OF THE
INTERIOR. THIS PERIOD OF ICING COULD BE MORE PROLONGED ACROSS SE CT
AS THE AFOREMENTIONED LLJ CONTINUES TO TRANSPORT WARMER AIR IN ALOFT
FOR A GOOD PART OF WED NIGHT.

WHEN ALL IS SAID/DONE...THERE IS GOOD POTENTIAL FOR SIGNIFICANT
SNOWFALL ACROSS MUCH OF THE INTERIOR...AND SIGNIFICANT ICING FOR
SOUTHEAST CT. LESSER SNOWFALL AMOUNTS ARE MORE LIKELY FOR NYC AND
LONG ISLAND...BUT IT WOULD NOT TAKE MUCH DEVIATION FROM THE ABOVE
SCENARIO TO BRING MORE SIGNIFICANT SNOWFALL/ICING FARTHER SOUTH TO
THESE AREAS AS WELL...AS HPC WWD FORECAST SUGGESTS.



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