Severe Thunderstorm Warning 128, NWS Tallahassee, FL

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE TALLAHASSEE FL
140 PM EDT SUN JUL 23 2000

CURRENTLY: 17Z MSAS ANALYZED Q-STRNY BOUNDARY NEAR AN AGS-MCN-GZH
LINE. LOW PRESSURE WAS SITUATED BETWEEN CSG & MCN...W/ SURFACE
TROUGHS OVER THE NRN/NERN GULF. WINDS WERE GENERALLY W-SW 5-10
KT...VRBL & GUSTY NEAR TSTMS. WSR-88D/S SHOWED ACTIVE CONVECTIVE
CLUSTER OVER THE FL BIG BEND EXTENDING SSWWD INTO THE NE GULF. TLH
HAS RECORDED 1.33" IN THE PAST 45 MINUTES W/ STRONG CELL OVERHEAD.
CELL MOTION WAS NE AT 10-15 KT. NRN EDGE OF ACTIVITY WAS ADVANCING
INTO EXTREME S GA. AREAS VOID OF SIG CLOUD COVER/PCPN HAD WARMED
INTO THE UPPER 80S TO NEAR 90. SOME CU FORMING OVER THESE AREAS &
EXPECT SHWRS/TSTMS TO DEVELOP QUICKLY BY MID AFTN. POTENTIAL STILL
EXISTS FOR ISOLD WET MICROBURSTS/DAMAGING WINDS W/ STRONGEST TSTM
CELLS...THUS SPC HAS INCLUDED OUR CWFA IN A SLGT RISK THRU EARLY
EVE.

SHORT RANGE/ZFP: 12Z MODELS IN DECENT AGREEMENT W/ STATIONARY UPPER
RIDGE OVER 4-CORNERS OF SWRN CONUS W/ SERIES OF SHORT WAVES RIDING
OVER RIDGE INTO MEAN UPPER TROUGH WHICH MOVES SLOWLY EAST FROM LOWER
MS VALLEY INTO TN VALLEY & GULF COAST STATES. MANUAL PROGS SHOW Q-STNRY
FRONT JUST NW OF OUR CWFA W/ SERIES OF SURFACE WAVES RIDING E/NEWD
ALONG IT. THE AIRMASS SOUTH OF THIS BOUNDARY WILL REMAIN VERY MOIST
& UNSTABLE (PWATS FROM 1.8-2.0"...LI/S -2 TO -4 & UNMODIFIED CAPES
FROM 1500-2500 J/KG). SOME DIFFERENCES EVIDENT W/ RESPECT TO QPFS.
12Z AVN INITIALIZED BEST W/ CONVECTION OVER FL CWFA & AVERAGE QPFS
OF 0.50-1.00". ETA NOT TOO FAR BEHIND W/ ITS QPF SOLUTION W/
0.50-0.75". NGM DRIEST OF THREE...WHICH BUILDS 500 MB HEIGHTS OVER
ERN U.S. FROM 24-48 HRS. WILL FOLLOW AVN POPS THIS FCST W/ SLIGHT
DECREASE IN POPS ON TUE SUPPORTED BY SOME DRYING OF THE MID LEVELS
(500-700 MB). FOR TONIGHT...CHANCE-GOOD CHANCE POPS BIG BEND/S GA ZONES
BORDERING FL...LOW CHANCE ELSEWHERE. MON...CHANCE DHN & ABY AREAS...
GOOD CHANCE PAM/PFN...LIKELY VLD/TLH/CTY. MON NIGHT...SLGT CHANCE
ALL BUT TLH/VLD AREAS (30%). TUE...CHANCE DHN/ABY AREAS...GOOD
CHANCE ELSEWHERE. LITTLE DAY-TO-DAY TEMP CHANGE THRU 48 HRS W/ BLEND
OF FAN/FWC NUMBERS.

MEDIUM RANGE/EFP: 00Z MRF SHOWS SPLIT RIDGE PATTERN W/ WEAK TROUGHINESS
& DAILY SEA BREEZE CIRCULATIONS TO MAINTAIN NEAR CLIMO POPS & TEMPS.

FIRE WEATHER: MOIST ONSHORE FLOW OFF GULF & CONSIDERABLE CLOUD COVER
WITH KEEP MAXIMUM TEMPERATURES AT OR BELOW 90 DEGREES AND MINIMUM
RELATIVE HUMIDITIES ABOVE FIRE WEATHER THRESHOLDS THRU MON.

MARINE: W/ SFC BNDRY N OF MARINE AREA AND UPPER TROF SITUATED OVER
GULF...GENERALLY SWLY WINDS 10-15 KTS & SEAS 2-3 FT SHOULD DOMINATE
THE NEXT 36 HRS. WIND & SEAS HIGHER NEAR WDLY SCT-SCT TSTMS.

PRELIMINARY TEMPS/POPS FOLLOW. COMMENTS WELCOME.

TLH 071/090 071/090 4635
PFN 075/087 075/087 3525
DHN 072/090 071/091 3424
ABY 072/091 071/091 3424
VLD 072/090 071/091 3635

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

MAJ