Severe Thunderstorm Warning 74, NWS Tampa Bay, FL

WEST CENTRAL AND SOUTHWEST FLORIDA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE TAMPA BAY AREA - RUSKIN
319 AM EST FRI DEC 13 2002

CURRENTLY...88D RETURNS INDICATE A LARGE AREA OF RAIN WITH A FEW
EMBEDDED THUNDERSTORMS OVER THE EASTERN GULF WATERS...SPREADING
ONSHORE OVER THE FA FROM SARASOTA NORTH EARLY THIS MORNING. LATEST
MSAS SFC ANALYSIS SHOWS DOUBLE STRUCTURE LOW PRESSURE AREA ONE OVER
SOUTHWEST MS AND ANOTHER DEEPENING LOW OVER THE GULF WATERS JUST SW
OF AQQ WITH A WARM FRONT EXTENDING E-SEWD FROM IT ACROSS THE S-
CENTRAL PENINSULA.

SHORT TERM...(TODAY-SUN)...GFS/ETA INITIALIZED FEATURES VERY WELL
THIS MORNING AND ARE VERY SIMILAR THROUGH THE FORECAST PERIOD...SO A
BLEND WILL BE USED. UPPER TROUGH OVER TX/LA WILL MOVE E-NEWD THROUGH
THE LOWER MS TODAY...THROUGH THE TN VALLEY TONIGHT AND INTO THE NERN
STATES ON SATURDAY. AS THE UPPER TROUGH LIFT NEWD ATTENDANT SFC LOW
WILL REDEVELOP OFF THE MID ATLANTIC THROUGH THE PERIOD. NORTHWARD
MOVING WARM FRONT MENTIONED ABOVE IN COMBINATION WITH DIVERGENT FLOW
ALOFT FROM UPPER JET WILL RESULT GOOD ISENTROPIC LIFT ACROSS THE FA
TODAY RESULTING IN CATEGORICAL POPS AND THE THREAT OF LOCALLY HEAVY
RAINS. IN ADDITION TO THE RAIN INCREASING LOW/MID LEVEL WIND FIELDS
CREATING HIGH HELICITY VALUES AND NORTHWARD MOVING WARM FRONT MAY
SUPPORT A BRIEF PERIOD OF STRONG TO SEVERE STORMS TOWARD SUNRISE THIS
MORNING. HOWEVER SIMILAR TO THE LAST RAIN EVENT...THE NEGATING FACTOR
FOR WILL BE THE AMOUNT OF INSTABILITY PRESENT. IF THE GREATER
INSTABILITY PRESENTLY TO THE SOUTH CAN GET IN HERE THEN A FEW PULSE-
SEVERE STORMS OR EVEN BRIEF TORNADOES OR MARINE WATERSPOUTS WILL BE
POSSIBLE. SEEING THAT LAPS LI TRENDS ARE SHOW INCREASING
INSTABILITY...WILL WORD FOR A FEW STRONG STORMS IN THE ZONES...AND
WILL HIT ON THE RISKS IN THE HWO LATER THIS MORNING.

BY LATER THIS AFTERNOON FLOW WILL BECOME UNIDIRECTIONAL WITH LESS
SHEAR...SO THE THREAT OF SEVERE WILL DIMINISH. IN ADDITION A COLD
FRONT WILL BE MOVING THROUGH THE REGION WITH DRIER AIR MOVING IN FROM
THE NORTH...SO RAIN CHANCES WILL BE DECREASING DURING THE AFTERNOON
HOURS AS WELL. RATHER TIGHT GRADIENT WILL SUPPORT BREEZY CONDITIONS
TODAY THROUGH SATURDAY AND WILL WORD FOR IN THE ZONES. EVEN WITH THE
DRIER AIR FILTERING IN LATER TODAY AND TONIGHT A VERY STRONG
SUBTROPICAL JET ALOFT WILL CONTINUE TO TRANSPORT MID/HIGH LEVEL
MOISTURE INTO THE FA FROM THE GULF...SO WILL WORD FOR A GOOD DEAL OF
MID/HIGH CLOUDS ALL ZONES TONIGHT THROUGH SATURDAY ESPECIALLY CENTRAL
AND SOUTHERN ZONES...THEN A BIT MORE SUNSHINE EXPECTED EVERYWHERE ON
SUNDAY AS THE JET AXIS SAGS FURTHER SOUTH TAKING THE CLOUDS WITH IT
AS SFC HIGH PRESSURE BUILDS IN. CAA EXPECTED IN THE WAKE OF THE
FRONT...BUT WITH FLOW ALOFT REMAINING OUT OF THE SW-W AS WEAK
TROUGHING PERSISTS OVER THE GULF...TEMPS LIKELY TO BE ONLY SLIGHTLY
BELOW SEASONAL LEVELS THROUGH THE PERIOD...WITH COLDEST READINGS
(NEAR FREEZING POSSIBLE) FAR NORTH SATURDAY NIGHT INTO SUNDAY
MORNING. THE MAV/MET/FWC NUMBERS ARE FAIRLY CLOSE AND ACCEPTED AND A
BLEND WILL BE USED.

EXTENDED(MON-THURS)...SFC HIGH PRESSURE OVER THE STATE ON MONDAY WILL
RESULT IN DRY AND SLIGHTLY BELOW SEASONAL LEVEL TEMPS CONTINUING. BY
TUESDAY THE HIGH SHIFTS EASTWARD ALLOWING AN EASTERLY FLOW TO DEVELOP
ACROSS THE FA WITH A SLOW MODERATING TREND EXPECTED. A REINFORCING
SFC HIGH WILL BUILD FROM NEW ENGLAND SOUTH TO THE GULF ON WEDNESDAY
AND THURSDAY. THIS WILL KEEP AN E-SELY FLOW OVER THE REGION WITH
SLOWLY INCREASING MOISTURE LEVELS...BUT NO POPS EXPECTED JUST YET.

MARINE...C-MAN SITES REPORTING E-SE WINDS IN THE 15-20 KNOT RANGE...
WHILE OFFSHORE BUOYS INDICATING WINDS 20-25 KNOTS WITH GUST AS HIGH
AS 44 KNOTS AT BUOY 42003 DURING THE LAST HOUR. CURRENT AND PROGD
GRADIENT SUPPORTS HOISTING SCA ALL LEGS EXCEPT WILL KEEP SCEC OVER
THE BAY WATERS. GFS WINDS ARE TO STRONG...SO WILL USE A BLEND OF THE
ETA/NGM. E-SELY FLOW WILL SHIFT TO THE WEST THIS AFTERNOON...THEN NW
TONIGHT AND SATURDAY. FLOW WILL WEAKEN AND SHIFT INTO THE NORTH ON
SUNDAY...THEN BECOME NE-E ON TUESDAY.

FIRE WEATHER...NO CONCERNS TODAY.

PRELIMINARY #S
BKV 073/048 062/037 9-00
TPA 072/053 065/045 8100
GIF 074/054 066/045 8100
SRQ 074/057 067/045 8100
FMY 076/058 069/049 7100

.TBW...SMALL CRAFT ADVISORY BONITA BEACH TO SUWANNEE RIVER OUT 60 NM.
       SMALL CRAFT EXERCISE CAUTION TAMPA BAY.

MCMICHAEL

FLZ039-042-043-048>052-055>057-060>062-065-131630-

HAZARDOUS WEATHER OUTLOOK
NATIONAL WEATHER SERVICE TAMPA BAY AREA - RUSKIN FL
505  AM EST FRI DEC 13 2002

THIS HAZARDOUS WEATHER OUTLOOK IS FOR WEST CENTRAL AND SOUTHWEST
FLORIDA.

.DAY ONE...TODAY:

...LOCALLY HEAVY RAINFALL LIKELY EARLY TODAY...
...ISOLATED STRONG TO SEVERE THUNDERSTORMS POSSIBLE EARLY TODAY...
...SMALL CRAFT ADVISORY ON THE GULF WATERS...

A STORM SYSTEM DEVELOPING OVER THE NORTHERN GULF THIS MORNING WILL
TRACK NORTHEAST INTO THE LOWER MISSISSIPPI VALLEY THROUGH TONIGHT.
A WARM FRONT ASSOCIATED WITH THIS SYSTEM WILL MOVE NORTH OF THE
TAMPA BAY AREA THROUGH THIS AFTERNOON. THIS FRONT COMBINED WITH
ABUNDANT MOISTURE AND AN UPPER LEVEL JET MOVING ACROSS THE GULF WILL
SUPPORT RAIN...SOME LOCALLY HEAVY THROUGH THE EARLY AFTERNOON HOURS.

THIS HEAVY RAIN MAY CAUSE MINOR FLOODING OF POOR DRAINAGE AND LOW
LYING AREAS. SMALL STREAMS MAY BRIEFLY EXCEED BANK FULL. AREA
RAINFALL WILL RANGE FROM 1 TO 2 INCHES...BUT LOCAL AMOUNTS UP TO 3
INCHES WILL BE POSSIBLE WHERE HEAVIER BANDS DEVELOP.

IN ADDITION TO THE HEAVY RAINS...AN INCREASINGLY WARM AND HUMID AIR
MASS COMBINED WITH FAVORABLE WIND SHEAR WILL INCREASE THE THREAT OF
STRONG TO SEVERE THUNDERSTORMS WITH DAMAGING WINDS AND POSSIBLE
SHORT LIVED TORNADOES OR MARINE WATERSPOUTS.

BY EARLY AFTERNOON THE THREAT FOR SEVERE WEATHER WILL BE DECREASING
HOWEVER A COLD FRONT MOVING THROUGH THE REGION MAY FIRE OFF
ADDITIONAL STORMS MAINLY FROM THE TAMPA BAY AREA SOUTH.

SEVERAL RIVERS ACROSS WEST CENTRAL FLORIDA ARE NEAR OR JUST ABOVE
FLOOD STAGE...AND ANY ADDITIONAL RAINFALL THROUGH LATE TODAY MAY
CAUSE STAGES TO RISE EVEN FURTHER.

RESIDENTS OF WEST CENTRAL AND SOUTHWEST FLORIDA ARE URGED TO REMAIN
ALERT TO RAPIDLY CHANGING WEATHER CONDITIONS TODAY...AND BE PREPARED
TO SEEK SAFETY SHOULD THREATENING WEATHER APPROACH. RESIDENTS LIVING
ALONG RIVERS AND FASTER FLOWING STREAMS SHOULD REMAIN ALERT TO ANY
RAPID RISES IN WATER LEVELS...AND SHOULD TAKE IMMEDIATE ACTION IF
FLOODING BE OBSERVED.

FOR MARINE INTERESTS...SOUTHWEST WINDS OF 20 TO 25 KNOTS WITH HIGHER
GUSTS WITH SEAS OF 6 TO 8 FEET WILL MAKE FOR VERY ROUGH BOATING
CONDITIONS TODAY AND A SMALL CRAFT ADVISORY IS IN EFFECT FOR THE NEAR
AND OFFSHORE WATERS...WHILE SMALL CRAFT EXERCISE CAUTION IS IN EFFECT
OVER THE TAMPA BAY.

STAY TUNED TO NOAA WEATHER RADIO OR YOUR LOCAL MEDIA OUTLETS FOR
ADDITIONAL STATEMENTS AND OR WARNING SHOULD THEY BECOME NECESSARY.

.DAYS TWO THROUGH SEVEN...SATURDAY THROUGH THURSDAY:

HAZARDOUS WEATHER IS NOT EXPECTED.

.SPOTTER CALL TO ACTION STATEMENT...

SPOTTER ACTIVATION MAY BE REQUIRED THIS MORNING.

FOR ADDITIONAL WEATHER INFORMATION, CHECK OUR WEB SITE AT
HTTP://WWW.SRH.NOAA.GOV/TBW

JCM