Severe Thunderstorm Warning 100, NWS Tallahassee, FL

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE TALLAHASSEE FL
152 PM EDT THU JUL 4 2002

CURRENTLY: WATER VAPOR IMAGERY SHOWS A DISTINCT SHORTWAVE DROPPING
DOWN FROM THE NORTH ACROSS NORTHERN ALABAMA. IN ADDITION...THE
LATEST MSAS DATA SHOWS A WEAK SURFACE LOW JUST NORTH OF MY CWFA. AS
A RESULT...SCATTERED TO NUMEROUS SHOWERS AND THUNDERSTORMS HAVE BEEN
ERUPTING ACROSS THE GULF WATERS FROM SOUTH OF PENSACOLA TO NORTH OF
TAMPA. RADARS ARE ALSO DETECTING SCATTERED STORMS CURENTLY
DEVELOPING JUST TO THE NORTH OF MY ALABAMA AND GEORGIA ZONES AND
HEADED SOUTH. ANTICIPATE A RATHER ACTIVE DAY AS SHORTWAVE CONTINUES
TO MOVE SOUTH AND DAYTIME HEATING ADDS FUEL TO THE FIRE.

MODELS/ZFP: IN THE UPPER LEVELS THE MODELS PROG THE SHORTWAVE AND
ASSOCIATED VORT MAX TO DROP DOWN FROM THE TN VALLEY TO THE CENTRAL
GULF COAST REGION...GENERALLY OVER THE MOBILE/PENSACOLA AREA BY
EARLY FRIDAY. DURING THE DAY ON FRIDAY ALL MODELS ARE SHOWING A WEAK
VORT LOBE DRAPED ACROSS SOME PORTION OF THE FORECAST AREA AS THIS
FEATURE SLOWLY MOVES SOUTH. BY SATURDAY AS THE VORT LOBE CONTINUES
ITS SOUTHWARD PROGRESSION MODELS ARE THEN SHOWING NVA ACROSS THE
FORECAST AREA FROM THE NORTHEAST.

AT THE SURFACE THE MODELS ARE SHOWING THE WEAK SURFACE LOW NEAR
COLUMBUS GEORGIA TO SLOWLY MOVE W OR SW WITH THE MODELS DIVERGING IN
THEIR SOLUTIONS BY MIDDAY FRIDAY. ALL MODELS SHOW A WEAK TROUGH THAT
EXTENDS FROM THE CAROLINAS AND ACROSS THE SE INTO THE CENTRAL GULF
COAST AREA...BUT MODEL WIND FIELDS SHOW A SURFACE CIRCULATION
GENERALLY OVER THE PANHANDLE AND THE ADJACENT COASTAL WATERS DURING
THE DAY ON FRIDAY. HOWEVER...BY LATE FRIDAY (00Z SAT) THE NGM HAS
THE SURFACE LOW MUCH FARTHER TO THE WEST OVER SRN LA...AS OPPOSED TO
THE AVN WHICH KEEPS THE LOW OVER THE FLORIDA PANHANDLE AND SE
ALABAMA WITH HIGHER MEAN RH VALUES NEAR THIS LOW. THIS EXPLAINS THE
VERY LOW POPS NUMBERS IN THE FWC GUIDANCE. THE ETA ONLY SHOWS A WEAK
BOUNDARY THAT EXTENDS FROM EAST GA ACROSS SRN AL AND INTO SRN LA.

TONIGHT: WILL BASE POPS MAINLY ON RADAR TRENDS...AND FROM WHAT I AM
SEEING NOW...I THINK 30-40% FOR TONIGHT LOOKS REASONABLE...BUT WILL
MONITOR RADARS UP TO THE LAST MINUTE BEFORE DECIDING.

FRIDAY: WITH THE VORT LOBE LINGERING ACROSS THE FORECAST AREA...PWS
STILL QUITE HIGH...AND WITH THE SEABREEZE CONTRIBUTION WILL USE
40-50% (40% NORTH ZONES-50% SOUTH).

FRIDAY EVENING: WILL USE 20 PERCENT ACROSS THE BOARD.

SATURDAY: MODELS QUITE A BIT DIFFERENT WITH THE ETA SHOWING THE MAIN
SURFACE LOW OVER SE ALABAMA WITH WINDS MAINTAINING A SOUTHERLY
COMPONENT OVER THE CWFA. AVN HAS THE LOW OVER THE GULF WATERS...WELL
SOUTH OF THE FLORIDA PANHANDLE...BUT WINDS STILL SE ACROSS THE
REGION. BY THIS TIME SLIGHTLY DRIER AIR HAS FILTERED INTO THE REGION
FROM THE NE AND BASED ON LOCAL SEABREEZE CLIMO...POPS IN THE 20-30%
RANGE ARE STANDARD FOR THE WIND REGIME THAT WILL BE IN PLACE BY
THEN. WILL GO 30 PERCENT ACROSS THE BOARD.

MARINE: WINDS MAINTAIN A SOUTHERLY COMPONENT AND WILL ALSO BE BELOW
CAUTION OR ADVISORY LEVELS.

FIRE WX: NO HIGHIGHTS.

EXTENDED (MONDAY THROUGH THURSDAY): MRF SHOWS THE SURFACE LOW WHICH
IS CURRENTLY JUST NORTH OF THE FORECAST AREA TO SLIDE TO THE W OR SW
AND EVENTUALLY END UP OVER THE WESTERN GULF AS HIGH PRESSURE BUILDS
FROM THE ATLANTIC MONDAY THROUGH TUESDAY. BY WEDNESDAY A FRONT
APPROACHES FROM THE NW AND IS PROGGED TO SLOW DOWN AND LIE JUST TO
THE NORTH OF MY EXTREME NORTHERN ZONES. WOULD EXPECT THAT THE THREAT
FOR SHOWERS AND STORMS WOULD BE GREATER DURING THE LATTER HALF OF
THE EXTENDED FORECAST WITH THE APPROACH OF THIS FRONT...BUT GUIDANCE
NUMBERS (MEX) ARE INDICATING EITHER A GOOD CHANCE TO LOW END OF
LIKELY CATEGORY THROUGHOUT THE ENTIRE FORECAST PERIOD...OR FOR THE
CHANCE TO DECREASE SLIGHTLY ON WED AND THU...WHICH DOESNT SEEM
REASONABLE. THEREFORE...WILL JUST GROUP THE ENTIRE EXTENDED PERIOD
TOGETHER AND KEEP A MENTION OF SCATTERED AFTERNOON AND EVENING
STORMS EACH DAY.

PRELIMINARY NUMBERS...

TLH 070/092 072/094  3523
PFN 073/090 075/090  4523
DHN 072/091 073/093  4423
ABY 071/092 072/093  3423
VLD 070/093 071/094  2423

.TLH...
.AL...NONE.
.GA...NONE.
.FL...NONE.

MOLLERE