DAY1SVR: Day 1 Convective Outlook

ACUS01 KWNS 021236
SWODY1
SPC AC 021234

DAY 1 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
0734 AM CDT TUE OCT 02 2012

VALID 021300Z - 031200Z

...NO SVR TSTM AREAS FORECAST...

...SYNOPSIS...
AN UPPER-LEVEL TROUGH POSITIONED OVER THE MID/LOWER MS VALLEY WILL
MOVE VERY LITTLE TODAY...WHILE FARTHER W...A STRONG SHORTWAVE TROUGH
AND ASSOCIATED SURFACE COLD FRONT WILL DIG SWD INTO THE NRN ROCKIES.
AN OCCLUDED SURFACE CYCLONE LOCATED OVER THE KY/IND BORDER THIS
MORNING WILL WEAKEN SIGNIFICANTLY DURING THE DAY AS IT LIFTS NWD
TOWARD LAKE MI. MEANWHILE...A COLD FRONT EXTENDING SWD INTO THE ERN
GULF OF MEXICO WILL GRADUALLY SHIFT EWD ACROSS SC/GA/NRN FL...WHILE
A WARM FRONT MOVES N THROUGH THE MID-ATLANTIC REGION.

...MID/UPPER OH VALLEY SEWD INTO THE CAROLINAS...
A BROKEN BAND OF SHOWERS AND ISOLATED THUNDERSTORMS EXTENDS SWD FROM
THE CNTRL APPALACHIANS INTO NRN FL THIS MORNING...WHILE PRE-FRONTAL
STORM CLUSTERS ARE MOVING NWD ACROSS NC. SELY SURFACE WINDS
JUXTAPOSED WITH A 30 KT LOW-LEVEL SLY JET IS YIELDING SUFFICIENT
LOW-LEVEL VERTICAL WIND SHEAR FOR ROTATING STORMS OVER VA INTO THE
CAROLINAS. THIS SHEAR COMBINED WITH WEAK BUOYANCY WILL RESULT IN A
VERY MARGINAL THREAT FOR AN ISOLATED/BRIEF TORNADO THROUGH LATE
MORNING...BUT THE THREAT WILL QUICKLY SUBSIDE AS THE LOW-LEVEL JET
EXPERIENCES RAPID WEAKENING BY MID-DAY. OTHERWISE...PW VALUES FROM
1.75-2.0 INCHES...MLCAPE VALUES RANGING FROM 500-1500 J/KG AND 30 KT
MEAN SWLY DEEP-LAYER FLOW MAY SUPPORT THE DEVELOPMENT OF A FEW
STRONG/SVR MULTICELLS POSING A THREAT FOR ISOLATED DAMAGING WIND
GUSTS DURING THE AFTERNOON.

FARTHER N OVER THE MID/UPPER OH VALLEY...WEAK SURFACE LOW PRESSURE
WILL SLOWLY MOVE N ACROSS THE AREA DURING THE AFTERNOON. AS THIS
OCCURS...MID TO UPPER 60S SURFACE DEWPOINTS ARE FORECAST TO ADVECT
NWD INTO THE REGION...AND WILL AID IN MUCAPE VALUES AROUND 500 J/KG
AS TEMPERATURES WARM INTO THE 70S. THIS ENVIRONMENT IS EXPECTED TO
SUPPORT ISOLATED THUNDERSTORM CLUSTERS SPREADING N-NEWD ACROSS WV
AND OH DURING THE AFTERNOON AND EVENING. DESPITE SURFACE WINDS
REMAINING BACKED OUT OF THE E-SE...SPEEDS THROUGH THE LOWEST 1-2 KM
AGL WILL BE WEAK AS THE LOW-LEVEL CYCLONE FILLS...WHICH IS EXPECTED
TO PRECLUDE A MORE SUBSTANTIAL THREAT FOR TORNADOES.
OTHERWISE...DEEP-LAYER VERTICAL WIND SHEAR WILL BE STRONG ACROSS THE
REGION /0-6 KM BULK WIND DIFFERENCE NEAR 60 KT/...AND WILL FAVOR THE
POTENTIAL FOR ORGANIZED THUNDERSTORM DEVELOPMENT. HOWEVER...THE
THREAT FOR MORE THAN AN ISOLATED DAMAGING WIND GUST IS EXPECTED TO
BE LOW DUE TO WEAK FORCING FOR ASCENT AND MARGINAL CAPE/LAPSE RATES.

..GARNER/THOMPSON.. 10/02/2012

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