SWODY1
SPC AC 251924
DAY 1 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
0124 PM CST TUE JAN 25 2011
VALID 252000Z - 261200Z
...THERE IS A SLGT RISK OF SVR TSTMS ACROSS THE FL PENINSULA THROUGH
TONIGHT...
...CENTRAL/N FL THIS AFTERNOON/EVENING...
AN EXTENSIVE PRE-FRONTAL SQUALL LINE CONTINUES TO EVOLVE OVER THE
CENTRAL/ERN GULF OF MEXICO...IN ADVANCE OF THE MIDLEVEL WAVE
APPROACHING THE LOWER MS VALLEY. THE LEAD BOWING SEGMENTS WITHIN
THE LARGER CONVECTIVE BAND ARE EXPECTED TO REACH THE COAST N OF
TAMPA BAY AROUND 2030Z. MEANWHILE...SURFACE TEMPERATURES HAVE
WARMED INTO THE MID-UPPER 70S WITH DEWPOINTS IN THE LOW-MID
60S...AND MLCAPE HAS LIKEWISE INCREASED TO 500-1000 J/KG. THE
DESTABILIZATION AND A CONCURRENT GRADUAL INCREASE IN VERTICAL SHEAR
WILL MAINTAIN THE ERN GULF SQUALL LINE ACROSS N/CENTRAL FL THIS
AFTERNOON INTO THIS EVENING...AND MAY SUPPORT ISOLATED STORM
DEVELOPMENT INLAND LATER THIS AFTERNOON. GIVEN THE ORGANIZED
CONVECTIVE STRUCTURES ALREADY OBSERVED OFFSHORE AND FAVORABLE TIMING
WITH THE DIURNAL CYCLE...WILL INTRODUCE 30% DAMAGING WIND
PROBABILITIES IN ADVANCE OF THE CONVECTION ACROSS N/CENTRAL FL.
LOCAL VWP/S ALREADY SHOW SUFFICIENT VERTICAL SHEAR FOR SUPERCELLS
WITH CURVED HODOGRAPHS AND 0-1 KM SRH AOA 250 M2/S2 ACROSS CENTRAL
AND N FL. FAVORABLE VERTICAL SHEAR WILL LIKELY BE MAINTAINED OVER
THIS AREA THROUGH THE AFTERNOON...WITH SOME MESOSCALE ENHANCEMENT
POSSIBLE IN ASSOCIATION WITH AN APPARENT MCV MOVING ENEWD OVER THE
FL BIG BEND. THE ENVIRONMENT APPEARS FAVORABLE FOR BOTH EMBEDDED
SUPERCELLS AND QLCS MESOVORTICES WHICH WILL POSE A THREAT FOR A
COUPLE OF TORNADOES.
THE REMAINDER OF THE OUTLOOK SCENARIO FROM 1630Z APPEARS ON TRACK
WITH NO ADDITIONAL CHANGES NECESSARY.
..THOMPSON.. 01/25/2011
.PREV DISCUSSION... /ISSUED 1010 AM CST TUE JAN 25 2011/
...FL...
SRN BRANCH S/W TROUGH WILL PROGRESS EWD ACROSS LWR MS VLY/NRN GULF
OF MEXICO THIS AFTERNOON TO SERN STATES BY 12Z WED AS IT CONTINUES
TO DEEPEN. SURFACE LOW ALONG THE SERN LA/SRN MS COAST WILL DEVELOP
ENEWD ALONG STRENGTHENING BAROCLINIC ZONE DEVELOPING NWD THROUGH NRN
FL/SRN GA BY LATE THIS AFTERNOON INTO TONIGHT.
GULF MOISTURE IS SPREADING NWD THRU FL PENINSULA ON STRENGTHENING
LOW LEVEL SLY FLOW WITH 850 WINDS TO 35-40KT BY MID AFTERNOON
CENTRAL FL PENINSULA NWD.
WITH INCREASING THUNDERSTORMS NOTED OVER NERN GULF AND LATEST
MESOSCALE MODEL GUIDANCE IT STILL APPEARS THERE IS THE POTENTIAL FOR
TWO DISTINCT TSTM REGIMES DURING THE DAY ONE PERIOD. THE DOMINANT
AND MOST PROBABLE REGIME WILL BE THE DEVELOPMENT OF A SQUALL LINE
AHEAD OF THE SYNOPTIC COLD FRONT WHICH WILL PROGRESS FROM THE NERN
GULF OF MEXICO EWD THROUGH AT LEAST THE NRN HALF OF THE PENINSULA
BETWEEN 00-06Z. BASED ON THE HIGHER RESOLUTION MODEL DATA
SETS...CONVECTIVE MODE WILL LIKELY BE LINEAR QLCS WITH THE POTENTIAL
FOR EMBEDDED BOWING STRUCTURES CAPABLE OF DAMAGING WIND GUSTS AND
PERHAPS A BRIEF TORNADO OR TWO.
THERE REMAINS UNCERTAINTY OF THE POTENTIALLY MORE SIGNIFICANT SECOND
REGIME WHICH COULD DEVELOP BY LATER THIS AFTERNOON OVER THE FL
PENINSULA WHERE HEATING WILL BE SUFFICIENT TO SUPPORT SURFACE BASED
THUNDERSTORMS. FORECAST SOUNDING DATA INDICATE LITTLE CAP WILL
REMAIN ONCE TEMPS WARM INTO THE MID 70S AND DEWPOINTS RISE INTO THE
MID 60S. AT THAT POINT MLCAPE OF 500-1000 J PER KG/ AIR MASS
COINCIDENT WITH 40-45 KT OF DEEP WLY SHEAR AND 0-1 KM SRH OF 150-250
M2/S2 WOULD BE SUPPORTIVE OF MORE DISCRETE STORM MODES INCLUDING
SUPERCELLS CAPABLE OF DAMAGING WINDS AND A FEW TORNADOES BY LATER
THIS AFTERNOON.
..COASTAL CAROLINAS...
MODEL GUIDANCE REMAINS CONSISTENT IN INDICATING THAT THE
TRACK OF THE DEVELOPING SURFACE LOW WILL REMAIN ALONG INTENSIFYING
COASTAL BOUNDARY WITH ANY MEANINGFUL INSTABILITY LIKELY REMAINING
OFFSHORE. HOWEVER WILL MAINTAIN LOW PROPS OF SEVERE VICINITY OUTER
BANKS AS SOME ELEVATED INSTABILITY INDICATED IN THE MODEL FORECAST
SOUNDINGS NEAR THE END OF THE PERIOD.
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