FXUS62 KTBW 010901
AFDTBW
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE TAMPA BAY RUSKIN FL
401 AM EST TUE DEC 1 2009
.SHORT TERM (TODAY THROUGH THURSDAY)...A COMPLEX WEATHER PATTERN IS
FORECAST TO TAKE SHAPE ON WEDNESDAY AS A SURFACE LOW DEVELOPS IN
THE WESTERN GULF AND LIFTS NE THROUGH THURSDAY. TODAY THROUGH
WEDNESDAY EVENING WILL BE SORT OF A TRANSITION DAY WITH THE MID
LEVEL RIDGE BEING PUSHED EASTWARD AS THE MID LEVEL TROUGH MOVES
INTO THE NORTHERN GULF. THE ASSOCIATED SURFACE LOW MOVING NEWD
THROUGH THE SOUTHERN STATES WILL DRAG A COLD THROUGH THE AREA BY
LATE WEDNESDAY AND INTO THURSDAY. THE HEAVIEST RAINFALL AND
STRONGEST DYNAMICS WILL REMAIN NORTH OF OUR AREA CLOSER TO THE
CENTER OF THE SYSTEM BUT LATEST GUIDANCE IS SHOWING SOME
POTENTIAL FOR SOME STRONG AND/OR MARGINALLY SEVERE STORMS ALONG
THE FRONT.
FOR TODAY THROUGH WEDNESDAY NIGHT...A WEAK AND DISSIPATING SURFACE
FRONT ASSOCIATED WITH A SYSTEM WELL EAST OF THE NEW ENGLAND COAST
IS CURRENTLY STRETCHED ACROSS THE PENINSULA. THIS WILL GIVE US
SOME EXCESS CLOUD COVER OVER THE REGION BUT MOST LIKELY WILL NOT
PRODUCE ANY RAINFALL. GFS IS A BIT TOO MOIST WITH THIS FRONT
SHOWING SOME RAINFALL ALONG THE NATURE COAST THIS MORNING. FAVORED
THE NAM WHICH BREAKS THIS FRONT DOWN THROUGH THE DAY. REGARDLESS
OF THIS FRONTAL BOUNDARY...SURFACE FLOW WILL GRADUALLY VEER
THROUGH TOMORROW AFTERNOON WITH A TIGHTENING PRESSURE GRADIENT
BETWEEN THE LOW TO THE WEST AND THE HIGH TO THE NORTHEAST. BREEZY
CONDITIONS WILL ENSUE WEDNESDAY INCREASING INTO THE 10-15KT ACROSS
THE REGION AND STRONGER OVER THE GULF. STRONG AND PERSISTENT WINDS
WILL WILL INCREASE THE COASTAL FLOOD THREAT FROM HILLSBOROUGH
NORTHWARD WITH TIDES RUNNING 1-3FT ABOVE NORMAL FOR SOUTH FACING
SHORES. BY WED AFTERNOON THE FRONTAL SYSTEM WILL LIFT NORTH OF THE
REGION. GUIDANCE KEEPS MOISTURE ALONG THE WARM FRONT NORTH OF THE
AREA SO NOT ANTICIPATING MUCH PRECIP BEFORE THE COLD FRONT MOVES
IN WED NIGHT.
FOR WED NIGHT THROUGH THURSDAY...SHOWERS AND THUNDERSTORMS ALONG
AND JUST AHEAD OF THE COLD FRONT WILL BEGIN TO PUSH INTO THE
NATURE COAST LATE WED AND SPREAD SOUTHWARD THROUGH THE MORNING ON
THURSDAY. GFS HAS BEEN PRETTY AGGRESSIVE WITH THIS SYSTEM BRINGING
INTO THE AREA WELL AHEAD OF THE NAM AND ECMWF WITH A MORE
SOUTHERLY POSITION. THE GFS HAS HAD A SOMEWHAT DIFFICULT TIME WITH
THIS SYSTEM SO HAVE FAVORED THE MORE CONSISTENT ECMWF AND NAM.
WITH THAT BEING SAID...TRIMMED THE SURFACE DOWN SLIGHTLY AND
BUMPED UP POPS LATE WEDNESDAY AND EARLY THURSDAY. FORECASTED
DYNAMICS HAVE COME UP A BIT MORE IMPRESSIVE SHOWING BETTER LIFT
AHEAD OF THE FRONT. A LOT WILL BE DEPEND ON HOW MUCH DAY TIME
HEATING WE CAN GET ON WEDNESDAY WHICH WOULD HELP INCREASE THE
SEVERE THREAT. FOR NOW...WILL MAINTAIN A CHANCE FOR THUNDERSTORMS
AND CANNOT RULE OUT AN ISOLATED TORNADO DUE TO STRONG
SPEED/DIRECTIONAL SHEAR ALONG THE FRONT.
TOWARDS THE END OF THE PERIOD THE QUESTION IS HOW THE FRONT WILL
BEHAVE AFTER IT PUSHES SOUTH OF THE CWA. GFS AND ECMWF KEEP THE
FRONT LINGERING CLOSE TO THE SOUTHERN THIRD OF OUR CWA SO WILL
MAINTAIN 40 POPS WITH A CHANCE OF SHOWERS.
.LONG TERM (THURSDAY NIGHT THROUGH MONDAY)...CONSIDERABLE CHANGES
IN MODEL GUIDANCE MAKE THIS EXTENDED PERIOD A BIT UNCERTAIN. WHILE
YESTERDAY THE GFS SOLUTIONS WERE SHOWING A FAIRLY SIGNIFICANT
INTRUSION OF DRY AND COOL AIR IN THE WAKE OF THE MID WEEK
SYSTEM...THE 00Z RUNS TONIGHT ARE QUITE A BIT DIFFERENT. THE
GENERAL CONSENSUS SEEMS TO BE THAT THE FRONT WILL CLEAR THE AREA
DURING THE MIDWEEK BUT STALL OUT ACROSS FAR SOUTHERN FLORIDA BY
EARLY FRIDAY AND REMAIN THERE AS A STATIONARY BOUNDARY. MEANWHILE
A VERY STRONG SHORTWAVE TROUGH WILL KICK OUT AROUND THE BASE OF
LONGWAVE TROUGH CENTERED ACROSS THE LAKES AND MISSISSIPPI VALLEY.
AS THIS SHORTWAVE EJECTS TOWARDS THE GULF LATE FRIDAY...ANOTHER
ROUND OF SURFACE CYCLOGENESIS IS FORECAST TO OCCUR IN THE
NORTHWESTERN GULF. THIS WILL INTERACT WITH THE STATIONARY BOUNDARY
TO PRODUCE ANOTHER ROUND OF ACTIVE WEATHER BY FRIDAY NIGHT AND
SATURDAY WITH THIS LOW TRACK BEING MUCH FARTHER SOUTH THAN THE
PREVIOUS ONE. SINCE PREVIOUS RUNS SHOWED HIGH PRESSURE AND COLD
TEMPERATURES FRIDAY NIGHT...THE NEW SOLUTION OF
CLOUDS...RAIN...AND TEMPS IN THE 50S AND 60S IS SIGNIFICANTLY
DIFFERENT. TRENDED THE GRIDS SHARPLY TOWARDS THE NEW EXTENDED GFS
SOLUTION INCLUDING TRYING TO BLEND THE PREVIOUS FORECAST WITH NEW
GUIDANCE. THIS WAS DIFFICULT AT BEST GIVEN THE DISPARITY BUT
LEANED TOWARDS THE NEW SOLUTIONS AS POSSIBLE. BY SUNDAY THE GFS
SHOWS THE HIGH PRESSURE BUILDING IN AND SO STUCK WITH THE COOLER
TEMPS DURING THAT TIME PERIOD.
&&
.AVIATION...DISCUSSION FOR 06Z TAFS. VFR EXPECTED OUTSIDE OF BRIEF
PATCHY MVFR FOG AROUND SUNRISE.
&&
.MARINE...A SURFACE LOW DEVELOPING IN THE WESTERN GULF WILL TRACK
NE THROUGH THURSDAY WITH A COLD FRONT DRAGGING EASTWARD. SURFACE
FLOW AHEAD OF THIS SYSTEM WILL VEER TO A MORE SOUTHERLY FLOW AND
INCREASE TO THE 15-20KT RANGE IN THE NEAR AND OFF SHORE WATERS BY
WEDNESDAY. SEAS WILL GRADUALLY BUILD TO THE 7-10FT RANGE BY
WEDNESDAY EVENING. SHOWERS AND THUNDERSTORM ACTIVITY WILL START
INCREASING IN THE COASTAL WATERS STARTING WEDNESDAY NIGHT AND
LASTING THROUGH THURSDAY AFTERNOON. SCA WILL MOST LIKELY BE NEEDED
BY TOMORROW.
&&
.FIRE WEATHER...NO FIRE WEATHER CONCERNS.
&&
.PRELIMINARY POINT TEMPS/POPS...
TPA 79 65 77 65 / 20 10 50 70
FMY 81 66 81 69 / 10 10 40 70
GIF 77 65 79 65 / 10 10 40 70
SRQ 78 67 77 66 / 10 10 50 70
BKV 76 64 78 59 / 20 10 50 70
SPG 80 67 76 66 / 20 10 50 70
&&
.TBW WATCHES/WARNINGS/ADVISORIES...
FL...COASTAL FLOOD WATCH FROM WEDNESDAY MORNING THROUGH THURSDAY
MORNING FOR CITRUS-HERNANDO-HILLSBOROUGH-LEVY-PASCO-
PINELLAS.
GULF WATERS...NONE.
&&
$$
SHORT TERM/MARINE/FIRE WEATHER...20/BARRON
LONG TERM/AVIATION...35/JOHNSON
