SWODY1
SPC AC 091239
DAY 1 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
0739 AM CDT TUE SEP 09 2008
VALID 091300Z - 101200Z
...THERE IS A SLGT RISK OF SVR TSTMS OVER SOUTH FL...
...THERE IS A SLGT RISK OF SVR TSTMS ACROSS PARTS OF NEW
ENGLAND...NY/PA...AND SOUTHWARD ACROSS VA/NC...
...NEW ENGLAND...
MORNING SATELLITE IMAGERY SHOWS A PROGRESSIVE SHORTWAVE TROUGH OVER
THE GREAT LAKES. THIS FEATURE WILL TRACK EASTWARD TODAY AS THE
ASSOCIATED 80-90 KNOT MID LEVEL JET MAX ROTATES ACROSS NY/PA AND NEW
ENGLAND. A BAND OF STRONG CONVECTION HAS BEEN INCREASING IN
COVERAGE OVERNIGHT AHEAD OF SURFACE COLD FRONT FROM MD/PA INTO
VT/NH. REFER TO MESOSCALE DISCUSSION NUMBER 2236 FOR FURTHER
DETAILS. EARLY VISIBLE SATELLITE IMAGES SUGGEST THAT WIDESPREAD
CLOUDS WILL LIMIT DAYTIME HEATING AHEAD OF THIS LINE...KEEPING
AFTERNOON CAPE VALUES AOB 750 J/KG OVER NEW ENGLAND.
NEVERTHELESS...STRONG LARGE SCALE FORCING ALONG/AHEAD OF FRONT WILL
MAINTAIN ORGANIZED CONVECTION THROUGH THE DAY AS STORMS MOVE
EASTWARD AND OFFSHORE. FORECAST SOUNDINGS INDICATE 35-50 KNOTS OF
EFFECTIVE SHEAR...WHICH INDICATES SOME THREAT OF SUPERCELL STORM
STRUCTURES. DAMAGING WINDS APPEAR TO BE THE MAIN SEVERE THREAT
TODAY OVER THIS REGION...BUT HAIL AND ISOLATED TORNADOES WILL ALSO
BE POSSIBLE IN STRONGEST CELLS. THREAT IS EXPECTED TO DIMINISH
AFTER SUNSET AS STORMS MOVE OFFSHORE AND DIURNAL COOLING OCCURS.
...DELMARVA TO NC...
FARTHER SOUTH FROM THE DELMARVA SOUTHWARD INTO NC...POCKETS OF
STRONG HEATING ARE MORE LIKELY. SURFACE DEWPOINTS WELL INTO THE 60S
AND LOWER 70S WILL YIELD MLCAPE VALUES OF 1000-2000 J/KG.
HOWEVER...WEAKER MID LEVEL FLOW FARTHER SOUTH WILL TEND TO DIMINISH
THE ORGANIZED NATURE OF THE CONVECTION AND MAY RESULT IN MORE WIDELY
SCATTERED SEVERE REPORTS. AGAIN...DAMAGING WINDS SHOULD BE THE MAIN
THREAT.
...LA/AR INTO SOUTHERN APPALACHIANS...
AFTERNOON THUNDERSTORMS WILL BE POSSIBLE TODAY ALONG/AHEAD OF COLD
FRONT ALL THE WAY SOUTHWESTWARD INTO PARTS OF AR/LA. WHILE
ORGANIZED SEVERE STORMS ARE NOT ANTICIPATED...A FEW CELLS MAY
PRODUCE LOCALLY GUSTY WINDS AND HAIL.
...FL...
HURRICANE IKE IS FORECAST TO MOVE ACROSS WESTERN CUBA AND INTO THE
GULF OF MEXICO LATER TODAY. PORTIONS OF FAR SOUTH FL AND THE KEYS
WILL REMAIN IN AT LEAST MARGINALLY FAVORABLE WIND FIELDS FOR
EMBEDDED SUPERCELLS AND ISOLATED TORNADOES. RISK OF TORNADOES
SHOULD DIMINISH AFTER DARK AS DIURNAL HEATING CYCLE ENDS AND
VERTICAL SHEAR OVER FL WEAKENS.
..HART/JEWELL.. 09/09/2008
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