Saturday, November 29, 2008

DAY2SVR: Nws Storm Prediction Center Norman Ok

ACUS02 KWNS 291711
SWODY2
SPC AC 291709

DAY 2 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
1109 AM CST SAT NOV 29 2008

VALID 301200Z - 011200Z

...THERE IS A SLGT RISK OF SVR TSTMS ACROSS PARTS OF CNTRL AND SRN
FL...

...FLORIDA/SRN GA...
A LARGE UPPER-LEVEL TROUGH OVER THE CNTRL U.S. TONIGHT WILL DEEPEN
AND CLOSE OFF OVER THE MS VALLEY SUNDAY. STRONG SOUTHWEST FLOW IS
FORECAST TO BE IN PLACE ACROSS THE GULF COAST STATES WHICH WILL
STRENGTHEN SATURDAY AS A MID-LEVEL JET MOVES NEWD ACROSS THE REGION.
AT THE SFC...A COLD FRONT WILL ADVANCE SEWD ACROSS THE FL PENINSULA
SATURDAY MORNING WITH THE FRONT MOVING INTO NCNTRL FL BY LATE
AFTERNOON. A LINE OF THUNDERSTORMS ALONG THE FRONT SHOULD BE ONGOING
IN THE FL PANHANDLE IN THE MORNING. THIS LINE SHOULD REMAIN INTACT
THROUGH THE AFTERNOON MOVING ACROSS CNTRL FL BY EARLY EVENING. OTHER
THUNDERSTORMS APPEAR LIKELY TO INITIATE AHEAD OF THE BOUNDARY ACROSS
SOUTH FLORIDA DURING THE AFTERNOON.

CONCERNING THE SEVERE POTENTIAL...A POWERFUL 100 TO 110 KT MID-LEVEL
JET IS FORECAST TO MOVE NEWD ACROSS NRN FL AND GA SATURDAY. THIS
FEATURE WILL CREATE STRONG VERTICAL SHEAR PROFILES ACROSS MOST OF
THE REGION EXCEPT FOR SOUTH FLORIDA WHERE MODERATE VERTICAL SHEAR IS
FORECAST. IN ADDITION...FORECAST SOUNDINGS SATURDAY AFTERNOON
SUGGEST PLENTY OF INSTABILITY WILL BE AVAILABLE FOR STRONG UPDRAFTS
WITH SFC DEWPOINTS REACHING THE LOWER 70S F SOUTH OF LAKE OKEECHOBEE
AND SBCAPE VALUES RANGING FROM 1500 TO 2000 J/KG. THE VERTICAL
SHEAR...INSTABILITY AND STRONG LOW-LEVEL SHEAR DUE TO A 50 TO 60 KT
LOW-LEVEL JET OVER MUCH OF FL WILL BE FAVORABLE FOR ROTATING STORMS
AND POSSIBLY A FEW TORNADOES. LCL HEIGHTS BELOW 300 METERS WILL
FURTHER AID THE TORNADO THREAT. THE TORNADO THREAT SHOULD BE
GREATEST WITH DISCRETE CELLS THAT DEVELOP AHEAD OF THE APPROACHING
LINE SATURDAY AFTERNOON. THE MAIN THREAT WITH THE SQUALL-LINE SHOULD
PREDOMINANTLY BE WIND DAMAGE DUE TO STRONG UNIDIRECTIONAL LOW-LEVEL
FLOW. HOWEVER...AN ISOLATED TORNADO CAN NOT BE RULED OUT ESPECIALLY
IF SOME ROTATING STORMS EMBEDDED IN THE LINE CAN PERSIST.

..BROYLES.. 11/29/2008

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