DAY3SVR: Nws Storm Prediction Center Norman Ok

ACUS03 KWNS 040733
SWODY3
SPC AC 040731

DAY 3 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
0231 AM CDT TUE SEP 04 2012

VALID 061200Z - 071200Z

...SYNOPSIS...
A COLD FRONT WILL CONTINUE MOVING ACROSS THE MIDWEST/OH VALLEY AND
INTO THE NORTHEAST THIS PERIOD...AS SHORT-WAVE TROUGHING SHIFTS
ACROSS THE AREA IN FAST WLY/CYCLONIC FLOW ALOFT.

MEANWHILE...A SECOND FRONT WILL BEGIN DIVING SEWD ACROSS THE PLAINS
AS A SHORT-WAVE TROUGH DIGS SEWD ON THE WRN FRINGE OF THE LARGER
UPPER VORTEX OVER CENTRAL CANADA. BOTH OF THESE FRONTS WILL FOCUS
ACTIVE CONVECTION THIS PERIOD.

...LOWER GREAT LAKES/UPPER OH VALLEYS SWWD INTO TN/KY...
A COLD FRONT WILL CONTINUE ADVANCING ACROSS THE MIDWEST/OH VALLEY
THIS PERIOD...REACHING THE LOWER LAKES/UPPER OH VALLEY REGION BY
LATE AFTERNOON. AHEAD OF THE FRONT...A DIURNALLY DESTABILIZING
WARM-SECTOR AIRMASS LIKELY TO SUPPORT AN INCREASE IN
LIKELY-TO-BE-ONGOING CONVECTION.

WITH MODERATE FLOW ALOFT EXPECTED ACROSS THE REGION...SOME
ORGANIZATION OF CONVECTION INTO LINES IS EXPECTED -- WITH ISOLATED
STRONGER CELLS LIKELY TO BECOME CAPABLE OF LOCALLY GUSTY WINDS AND
SOME HAIL. THIS THREAT SHOULD EXTEND INTO EARLY EVENING AS STORMS
MOVE INTO THE APPALACHIANS...BUT EXPECT CONVECTION TO DIMINISH
OVERNIGHT AS COOLING/STABILIZATION COMMENCES.

...KS/OK AND VICINITY...
WEAK/HIGH-BASED DESTABILIZATION ACROSS THE KS/OK VICINITY IS
EXPECTED DURING THE AFTERNOON...AHEAD OF THE UPPER SYSTEM DIGGING
SEWD ACROSS THE NRN HIGH PLAINS. WITH BROAD/DIFFUSE LOW PRESSURE
EXPECTED ACROSS THE AREA -- SUPPORTED BY A WEAK LEAD FEATURE ALOFT
SHIFTING ESEWD OUT OF CO -- ISOLATED/HIGH-BASED SHOWERS AND
THUNDERSTORMS SHOULD DEVELOP DURING THE AFTERNOON. AIDED BY 40 KT
MID-LEVEL WSWLYS ALOFT...A FEW STRONGER STORMS MAY EVOLVE WITH
TIME...WHICH MAY BECOME CAPABLE OF PRODUCING
ISOLATED/EVAPORATIVELY-AIDED WIND GUSTS AND/OR MARGINAL HAIL.

AS THE FRONT DIVES SEWD ACROSS THE PLAINS DURING THE EVENING AND A
SWLY LOW-LEVEL JET DEVELOPS OVER THE WARM SECTOR...STORMS WILL
LIKELY CONTINUE OVERNIGHT. GIVEN THE STRENGTH OF THIS FRONT...A FEW
STRONGER/LOCALLY SEVERE STORMS WILL LIKELY PERSIST THROUGH THE END
OF THE PERIOD. ATTM...WILL INTRODUCE ONLY A BROAD 5% THREAT
AREA...BUT UPGRADE TO SLIGHT RISK MAY BECOME NECESSARY IN LATER
FORECASTS.

..GOSS.. 09/04/2012

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