Wednesday, December 1, 2010

DAY1SVR: Day 1 Convective Outlook

ACUS01 KWNS 011947
SWODY1
SPC AC 011945

DAY 1 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
0145 PM CST WED DEC 01 2010

VALID 012000Z - 021200Z

...NO SVR TSTM AREAS FORECAST...

.CHANGE TO PREV FORECAST...

1. REMOVE SLIGHT RISK FROM MID-ATLANTIC REGION...

NARROW BAND OF CONVECTION CONTINUES TO PROGRESS EWD THROUGH HUDSON
VALLEY/SE NY AND WRN LONG ISLAND AT 19Z ALONG A STRONG COLD FRONT.
MESOANALYSIS DEPICTS A NARROW WEDGE OF MID-50S SURFACE DEW POINTS
AHEAD OF THIS BAND AS FAR E AS WRN MA...CNTRL CT AND ERN LONG
ISLAND...PROVIDING JUST ENOUGH THERMAL BUOYANCY FOR NON-ZERO THREAT
FOR A CONVECTIVELY-INDUCED DAMAGING WIND REPORT. GIVEN THAT THE
STRONGEST WIND GUSTS WERE GRADIENT-DERIVED /ISALLOBARIC COMPONENT/
AHEAD OF THE CONVECTION AND THE INCREASINGLY STABLE BOUNDARY LAYER
WITH EWD EXTENT...EXPECT THAT CONVECTIVELY-ENHANCED WIND DAMAGE
THREAT WILL BE LIMITED IN AREAL COVERAGE LATE THIS AFTERNOON. WILL
MAINTAIN A LOW SEVERE WIND PROBABILITY INTO WRN MA...CT AND ERN LONG
ISLAND...BUT HAVE ELECTED TO REMOVE THE SLIGHT RISK FOR THIS REASON.

..RACY/MEAD/GARNER.. 12/01/2010

.PREV DISCUSSION... /ISSUED 1015 AM CST WED DEC 01 2010/

...MID ATLANTIC COAST/SRN NEW ENGLAND...

INTENSE VORTICITY MAXIMUM AND ASSOCIATED 100+ KT MIDLEVEL JET STREAK
OVER THE TN VALLEY INTO CNTRL/SRN APPALACHIANS WILL CONTINUE TO LIFT
NEWD WITH A CORRIDOR OF 200+ M/12 HR HEIGHT FALLS OVERSPREADING THE
REGION THROUGH THE PERIOD. AT THE SURFACE...STRENGTHENING COLD
FRONT FROM THE LEE OF LAKE ONTARIO SWD TO CHESAPEAKE BAY AND FAR ERN
NC AS OF 15Z WILL SURGE EWD TO OFF THE MID ATLANTIC COAST BY
AFTERNOON...AND EVENTUALLY THROUGH MUCH OF NEW ENGLAND BY THU
MORNING.

12Z OBSERVED SOUNDINGS AND CURRENT SURFACE OBSERVATIONS INDICATE
THAT COLD FRONT IS NOW INTERACTING WITH THE REMAINING ONSHORE AXIS
OF HIGHER THETA-E AIR OVER ERN NC INTO THE TIDEWATER REGION...WITH A
COMPARABLY COOLER AND DRIER BOUNDARY LAYER PRESENT AHEAD OF THE
FRONT NWD INTO THE HUDSON VALLEY. A SMALL TEMPORAL/SPATIAL RISK FOR
LOCALLY DAMAGING WIND GUSTS WILL BE POSSIBLE FOR THE NEXT HOUR OR SO
OVER DE PERHAPS INTO SERN PA/SRN NJ WHERE CONVECTION HAS RECENTLY
INTENSIFIED ALONG THE NRN EDGE OF LOW-LEVEL MOIST AXIS.
ELSEWHERE...ISOLATED STRONG WIND GUSTS WILL BE POSSIBLE WITH THE
PASSAGE OF FORCED CONVECTIVE BAND ALONG THE FRONT...THOUGH THE
STABLE BOUNDARY LAYER CONDITIONS SHOULD PRECLUDE A MORE SUBSTANTIAL
SEVERE THREAT.

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