Severe Thunderstorm Warning 75, NWS Tampa Bay, FL

WEST CENTRAL AND SOUTHWEST FLORIDA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE TAMPA BAY AREA - RUSKIN FL
200 PM EDT SAT AUG 26 2000

NOT MUCH CHANGE TO RECENT THINKING ON THIS PACKAGE.  IN GENERAL...
THE FARTHER N ONE GETS THE LESSER PROBABILITY OF ANY DECENT
RAINFALL...AND EVEN THE SW CORNER MAY BECOME RELATIVELY DRY IN
TIME.  MORE ON THIS IN THE EXTENDED DISC...

ONCE AGAIN...THE ETA/AVN ARE IN GOOD AGREEMENT THROUGH THE FIRST
48H.  THE NGM HAS TRENDED AWAY FROM IT'S SOLN OF MOVING THE TUTT
AXIS NW...BUT STILL TRIES TO DO IT (WHY?) DESPITE THE STRENGTHENING
NNW FLOW AROUND CUTTING-OFF LOW DIVING INTO THE S MID ATLC STATES.
IN THAT VEIN...HAVE BOUNCED IT'S SOLN ONE MORE TIME.

SHORT TERM...TONIGHT...STILL APPEARS THAT BEST CHC FOR PCPN (AND
LONGEST DURATION) WILL BE IN THE SW WHERE UPR JET DIVERGENCE
INTERSECTS ACTIVITY MOVING WNW ALONG ECSB/FRONT PORTION OF TUTT
AXIS.  ELSW...SCT TO WDLY SCT LATE AFTN/ERLY EVE CONVECTION WILL
END...FOLLOWED BY FAIR SKIES.

SUN...TONGUE OF LOWER MEAN RH REMAINS/MOVES ACRS THE N CWFA (ALSO
SHOWN BY LOWER PCP WATER VALUES)...AND MSTR GRDLY INCREASES FARTHER
S.  HOWEVER...MOST AREAS ARE UNDER SUBSIDENCE BETWEEN WKNG SHEAR
AXIS IN THE SE U.S. AND TUTT LOW.  AVN ACTUALLY APPEARS TOO DRY ESP
S...SO WILL BLEND THE AVN/ETA AND LEAVE GOOD CHC POPS S (AS WELL AS
MORE CLDS).

SUN NIGHT...PROBABLY A CARBON COPY OF TONIGHT...AND PERHAPS DRIER
BASED ON SOUTHWARD MIGRATION OF DRY TONGUE.

MON...HERE'S WHERE THE ETA/AVN DIVERGE.  THE AVN SHOVES THE DRY AIR
THRU THE ENTIRE CWFA AND REALLY PINS THE TUTT LOW OVER THE
BAHAMAS. THE ETA SEEMS TO MERGE MOISTURE FROM THE WAVE MOVING OFF
THE CAROLINA COAST WITH THE TROPICAL MOISTURE.  IN ANY CASE...H50-
H25 NW FLOW WILL CONTINUE TO HOLD EVERYTHING IN CHECK.

SYNOPTICALLY...THE AVN MAKES THE MOST SENSE.  HOWEVER...WILL ACCOUNT
FOR CLIMO AND THE PSBLTY THAT IT IS OVERDOING THE STRENGTH/DEPTH OF
THE MID ATLC SYS AND LEAVE PSNY/CHC POPS EVERYWHERE.  THIS IS...
HOWEVER...A MORE OPTIMISTIC CHANGE TO THE CURRENT EFP.

EXTENDED...HERE'S WHERE IT GETS INTERESTING.  THE BIG QUESTION
REMAINS:  HOW QUICKLY WILL THE SRN MID ATLC CUTOFF ERODE...ALLOWING
(AT LONG LAST) MID-SOUTH RIDGE TO OVERSPREAD AREA?  THE 12Z AVN HAS
CHANGED IT'S TUNE FROM THE 00Z MRF. WE'VE MODIFIED THE MRF
SOLN FOR NOW AS THE 12Z AVN HAS COME IN LINE WITH THE ECMWF IN
MAINTAINING IMPRINT OF MID ATLC CUTOFF (AND HENCE H50-H25 N FLOW).

THIS WOULD TEND TO INHIBIT RAPID SFC LOW DVLPMT AND KEEP IT'S TRACK
TO OUR E.  PER COORD W/NCEP...WILL BACK EFP TO CLIMO WX (PCLDY...
SCT POPS) THRU THE PERIOD.

MARINE:  LOOKIN' QUIET FOR THE SHORT TERM.  FOR THE EFP...I'VE
GREATLY MODIFIED THE MRF SOLN IN FAVOR OF THE NEW AVN/ECMWF...AND
WILL CARRY NO MORE THAN 15 KT (FROM THE NE) ATTM.

HOPEFULLY...WE CAN HONE IN ON THE MIDWEEK WX AS THE SOLUTION BECOMES
MORE EVIDENT.

FIRE WX:  NO PROBLEMS.

PRELIM NUMBERS:
TPA BB 074/091/074/091 2324
FMY TT 073/090/073/090 5545 88

.TBW...NONE.

GOLDSMITH