Severe Thunderstorm Warning 95, NWS Tallahassee, FL

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE TALLAHASSEE FL
155 PM EDT FRI AUG 13 1999

12 UTC MODEL RUNS IN GOOD AGREEMENT THIS FORECAST PERIOD. THEY
FORECAST A SHORTWAVE (AND ASSOCIATED COLD FRONT) TO MOVE INTO THE
CWA ON SATURDAY...AND THEN QUICKLY EXIT TO THE NORTHEAST...LEAVING A
WEAK FRONT TO DIE ACROSS THE CWA THROUGH MONDAY. THERE ARE TWO
FORECAST PROBLEMS THIS PERIOD...POPS AND HEAT ADVISORIES.

IT HAS TAKEN AWHILE...BUT SCATTERED CONVECTION IS BREAKING OUT NEAR
THE OUTER EDGES OF OUR CWA. WITH SUCH HIGH CAPES...EXPECT ALMOST
HALF THE AREA TO RECEIVE RAIN...WITH A FEW BEING SEVERE (LIKE
YESTERDAY). ON SATURDAY THE SURFACE-700MB FLOW WILL BE WEAKER THAN
TODAY...THUS ALLOWING FOR A BETTER SEA BREEZE. ALSO...THERE SHOULD
BE GOOD MOISTURE FLUX CONVERGENCE AHEAD OF THE APPROACHING COLD
FRONT. WITH THIS REASONING...I WILL GO LIKELY POPS ACROSS THE
BOARD...WHICH IS QUITE A DEVIATION FROM MOS (ESPECIALLY FWC
GUIDANCE). I WILL ALSO LEAVE OUT THE TYPICAL AFTERNOON POPS WORDING
DUE TO THE UNCERTAINTY OF ANY PRE-FRONTAL ACTIVITY. AS FOR
SUNDAY...THE MODELS ARE IN GOOD AGREEMENT IN BRINGING MID-LEVEL DRY
AIR BACK INTO THE WESTERN CWA AS THE 500MB HIGH RAPIDLY REBUILDS
OVER TX. AT THIS POINT ITS TOO CLOSE A CALL AS TO WHETHER THIS WILL
INHIBIT CONVECTION AS MUCH AS FWC IS PREDICTING. WILL GO CHANCE
POPS...WITH HIGHER CHANCES EAST AND LOWER CHANCE NORTH AND WEST.

ALTHOUGH FWC/FAN GUIDANCE FORECASTS HEAT ADVISORY CRITERIA
TOMORROW...WILL LET MID SHIFT DECIDE WHETHER TO REISSUE TOMORROW. AM
CONCERNED THAT APPROACHING FRONT WILL SPAWN ENOUGH CONVECTION (AND
MID-HIGH CLOUDS) TO INHIBIT SOLAR INSOLATION. WILL UNDERCUT GUIDANCE
A LITTLE ON TEMPS AND JUST HIGHLIGHT HEAT INDICES IN THE BODY.
THANKS BHM/ATL/MIA FOR COORDINATION.

PRELIM NUMBERS:

TLH 76 95 74 94 73 262
PFN 78 92 75 92 75 262
DHN 76 95 72 96 72 262
ABY 76 95 73 93 72 262
VLD 76 95 73 95 73 262

FOURNIER