Severe Thunderstorm Warning 23, NWS Tampa Bay, FL

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE TAMPA BAY-RUSKIN FL
252 PM EDT WED APR 28 1999

CURRENTLY NUMEROUS OUTFLOW BNDRYS NOTED ON SATL LOOP COMBINING WITH
SUFFICIENT MSTR AND INSTABILITY PWS 1.5 AND LIS -8 IS RESULTING
IN A LARGE AREA OF SHOWERS AND THUNDERSTORMS OVER MY INTERIOR ZONES
FROM LAKE PLACID NORTH TO HAINES CITY. IN ADDITION LARGE CLUSTERS OF
TSTMS ONGOING OVER THE NERN GULF WATERS. AS THE AFTERNOON CONTINUES
EXPECT TO SEE THE BEST AREAL COVERAGE OF STORMS TO CONTINUE OVER MY
INTERIOR ZONES...AND WOULD SUGGEST AT LEAST GOOD CHANCE CATEGORY
MENTION INTO THE EARLY EVENING HOURS. AS FOR MY COASTAL ZONES OUTFLOW
BNDRYS FROM GULF ACTIVITY IN CONJUNCTION WITH WCSB BNDRY MAY HELP TO
FIRE OFF CONVECTION ALONG THE IMMEDIATE COASTAL LOCATIONS LATER THIS
AFTERNOON AND WOULD RECOMMEND AT LEAST CHANCE CATEGORY POPS FOR THE
EVENING HOURS.

FOR TONIGHT...ALL CONVECTION SHOULD BEGIN TO WIND DOWN AFTER SUNSET
WITH LOSS OF SFC HTG AND WITH NVA MOVING INTO THE FA ON BACK SIDE OF
WEAK SHORT WAVE TROUGH MOVG EWD. SKIES SHOULD BECOME PARTLY CLOUDY
LATE TONIGHT AND WITH ADDED GROUND MOISTURE FROM THIS AFTERNOONS
PRECIP WILL LIKELY SEE AREAS OF FOG AND LOW CLOUDS DEVELOP AND
MENTION IN ZONES LOOKS IN ORDER.

FCST...HIGH AMPLIFIED PATTERN WITH OMEGA TYPE BLOCK OVER THE CENTRAL
U.S. WILL CONTINUE THRU THIS FCST CYCLE. ALL SHORT RANGE MODELS ARE
IN RELATIVELY GOOD AGREEMENT WITH THIS SCENARIO THRU 36 HRS...THEN
SOME SUBTLE DIFFERENCES ARE NOTED. CLOSED LOW OVER THE SW U.S. WILL
AMPLIFY SOME WHILE CLOSED LOW OVER THE UPR MS VALLEY MOVES SEWD WITH
ENERGY FROM CANADIAN MARITIMES CLOSED LOW DROPPING SWWD INTO THIS
LOW AND FORMING A CLOSED LOW OVER THE SERN GULF STATES VCNTY SC/GA
BORDER BY 12Z ON FRIDAY WITH A WEAK SFC REFLECTION EAST OF KJAX.
AVN/NGM AGREE ON THIS WHILE ETA KEEPS THIS TROUGH MORE OPENED UP AND
MOVES IT FURTHER EAST. WITH THE OMEGA BLOCKING TYPE PATTERN ALREADY
IN PLACE I CANT SEE WHY ETA WOULD BE SO PROGRESSIVE THUS WILL LEAN
TOWARD AVN/NGM SOLUTION IN THIS PACKAGE. WITH LITTLE OVERALL CHANGES
TO STABILITY OR MSTR PARAMETERS...THE THREAT OF SHOWERS AND TSTMS
WILL CONTINUE ON THURSDAY WITH HIGHEST POPS CONTINUING TO RESIDE OVER
MY INTERIOR ZONES WHERE E/W COAST SEA BREEZE AND OUTFLOW BNDRY
COLLISION TAKE PLACE. AS FOR TEMPS PREFER WARMER LOOKING FAN MINS TO
ACCOUNT FOR LIGHT WESTERLY FLOW OFF THE GULF...AND BLEND OF FAN/FWC
WITH MAXS.

EXTENDED...ON FRIDAY THE WEATHER MAY BECOME VERY INTERESTING ACRS MY
NRN INTO N-CENTRAL FA AS CLOSED UPR AND SFC LOWS WITH TRAILING FRONT
BEGINS TO AFFECT THE REGION. ATTM SOME STRONG TSTMS MAY BE POSSIBLE
AS COLD POOL ALOFT WITH UPR LOW WORKS IT WAY SOUTH INTO THE FA. IN
ADDITION COOLER TEMPS ARE EXPECTED DUE TO CLOUDS AND PRECIP.

MARINE...CONTINUED SOUTHWEST TO WESTERLY FLOW AROUND 10 KNOTS SHOULD
DO IT THROUGH THURSDAY WITH PM SEA BREEZE DVLPG. NO HIGHLIGHTS ARE
NEEDED.

TPA BB 071/086 070/082 064 57343
FMY BB 070/088 070/085 066 57343
LAL TT 070/090 069/086 065 57564

MCMICHAEL