SPC AC 041940
DAY 1 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
0140 PM CST FRI DEC 04 2009
VALID 042000Z - 051200Z
...THERE IS A SLGT RISK OF SVR TSTMS ACROSS THE SOUTHERN HALF OF THE
FL PENINSULA...
...SOUTH FL...
ADJUSTED THE ONGOING SLIGHT RISK TO INCORPORATE MORE OF THE SOUTHERN
FL PENINSULA...BUT FEW CHANGES TO PRIOR OUTLOOK REASONING WITH THE
PRIMARY SEVERE THREAT STILL EXPECTED LATER TONIGHT. SHOWERS WITH
SOME LIGHTNING PRODUCING CONVECTION SHOULD GRADUALLY BECOME MORE
COMMON INTO TONIGHT...WITH THE BULK OF THIS OCCURRING TO THE NORTH
OF A GRADUALLY NORTHWARD RETREATING FRONTAL BOUNDARY ACROSS THE FL
PENINSULA AHEAD OF AN AMPLIFYING SOUTHERN STREAM SHORTWAVE TROUGH
FROM TX TO THE CENTRAL GULF COAST STATES. BUT AS THE UPPER SYSTEM
APPROACHES/DEEP LAYER WIND FIELDS STRENGTHEN AND A MOIST/POTENTIALLY
UNSTABLE AIRMASS RETURNS NORTHWARD OVER SOUTHERN
PENINSULA...POTENTIAL FOR SURFACE BASED STORMS CAPABLE OF DAMAGING
WINDS/FEW TORNADOES WILL INCREASE MAINLY LATE TONIGHT/EARLY
SATURDAY.
..GUYER.. 12/04/2009
.PREV DISCUSSION... /ISSUED 1020 AM CST FRI DEC 04 2009/
...FLORIDA...
VIGOROUS UPPER TROUGH AND ASSOCIATED STRENGTHENING POLAR JET WILL
TRANSLATE EWD FROM CURRENT LOCATION SRN PLAINS ACROSS THE SERN
STATES BY LATER TONIGHT. LOW LEVEL RESPONSE WILL BE FOR FRONTAL BAND
ACROSS S FL TO BEGIN RETURNING NWD THIS AFTERNOON AS A WARM FRONT
POSSIBLY REACHING AS FAR N AS A TPA-MLB LINE OVERNIGHT.
IT NOW APPEARS THAT THE STRONG JET DYNAMICS COUPLED WITH THE INFLUX
OF THE VERY MOIST/MARGINALLY UNSTABLE AIRMASS FROM THE SERN GULF OF
MEXICO WILL PROVIDE THE INGREDIENTS FOR A CONDITIONAL THREAT OF
SEVERE THUNDERSTORMS ALONG AND S OF WARM FRONT PRIOR TO THE END OF
THE PERIOD...POSSIBLY BY 06Z.
GIVEN THE POTENTIAL FOR STRONG LOW LEVEL SHEAR UPWARDS TO 40KT IN
THE SFC-1KM LAYER VICINITY OF THE WARM FRONT ALONG WITH 60KT OF DEEP
LAYER SHEAR AS THE STRONG POLAR JET CROSSES THE FL PANHANDLE/SRN GA
OVERNIGHT...SUPERCELLS INCLUDING POSSIBLE TORNADOES WILL BECOME A
CONCERN TONIGHT. PRIMARY THREAT EXPECTED TO BE AFTER 06Z WITH THE
APPROACH OF THE GULF SURFACE WAVE.
BY AND SHORTLY AFTER 12Z A MORE ORGANIZED SQUALL LINE WILL POSSIBLY
BE MOVING INLAND ACROSS S FL AS SURFACE LOW WILL QUICKLY BE
REDEVELOPING OFF THE SERN COAST OVER THE WARM GULF STREAM WATERS
WITH WINDS QUICKLY VEERING TO WESTERLY DURING THE MORNING.
CLICK TO GET WUUS01 PTSDY1 PRODUCT
NOTE: THE NEXT DAY 1 OUTLOOK IS SCHEDULED BY 0100Z
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