Area Forecast Discussion
Issued by NWS Tampa Bay Area, FL

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FXUS62 KTBW 251904
AFDTBW

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE TAMPA BAY RUSKIN FL
304 PM EDT SAT APR 25 2015

.SYNOPSIS...
19Z WATER VAPOR AND H4 RAP ANALYSIS SHOWING A BROAD RIDGING
PATTERN IN PLACE OVER THE EASTERN GULF OF MEXICO AND FLORIDA
PENINSULA. UPPER LEVEL SHORTWAVE PASSING TO OUR NORTH WILL ACT TO
FLATTEN THE FLOW TO A MORE ZONAL CONFIGURATION BY THIS EVENING AND
THROUGH THE DAY ON SUNDAY. 12Z KTBW SOUNDING PROFILE SHOWED WE
STILL HAVE THE INFLUENCE OF THE RIDGE OVERHEAD WITH A FAIRLY WELL
DEFINED SUBSIDENCE INVERSION SHOWING UP AROUND 800MB. THE
RESULTING CAP IS PRETTY STRONG (AT LEAST OVER THE CENTRAL AND
SOUTHERN ZONES) AND SINCE WE WILL NOT BE SEEING MUCH IN THE WAY OF
HEIGHT FALLS...IT WILL TAKE CONSIDERABLE SURFACE HEATING TO
OVERCOME THIS INHIBITION. THE KJAX SOUNDING STILL SHOWED A BIT OF
A CAP...BUT NOT AS IMPRESSIVE...SO THE INHIBITION DOES WEAKEN
SOMEWHAT TOWARD OUR FAR NORTHERN ZONES.

AT THE SURFACE...
FLOW IS TURNING TO THE SOUTH AND SOUTHWEST AS THE GRADIENT BEGINS
TO TIGHTEN BETWEEN HIGH PRESSURE RIDGING THROUGH THE FLORIDA
STRAITS...AND LOW PRESSURE/WARM FRONTAL FEATURE PASSING WELL TO
OUR NORTH. THE UPPER ENERGY PASSING OVER THE SOUTHEAST CONUS
COMBINED WITH THE LIFT ASSOCIATED WITH THE WARM FRONT IS RESULTING
IN SEVERAL ROUNDS OF STRONG TO SEVERE THUNDERSTORMS ALONG THE
I-10 CORRIDOR OF FLORIDA UP INTO GA. HOWEVER...APPEARS THIS
INCLEMENT WEATHER WILL REMAIN TO THE NORTH OF OUR FORECAST ZONES.

&&

.SHORT TERM...
REST OF TODAY...
SEA BREEZE BOUNDARY PUSHED VERY QUICKLY INLAND TODAY ON THE
STRENGTH OF THE SYNOPTIC SOUTHWESTERLY FLOW. SAW JUST A FEW BRIEF
SHOWERS POP UP ALONG THIS BOUNDARY TO THE SOUTH OF THE I-4
CORRIDOR...BUT THESE ARE NOW EXITING THE FORECAST AREA TOWARD THE
FLORIDA I-95 CORRIDOR. SUBSIDENCE AND THE CAPPING ALOFT WILL
GENERALLY NOW RESULT IN A DRY AND BREEZY REST OF THE AFTERNOON
AND EVENING ACROSS WEST CENTRAL AND SOUTHWEST FLORIDA.

TONIGHT...
MAJORITY OF DIURNAL CONVECTION WILL BE OVER TOWARD THE I-95
CORRIDOR THIS EVENING WITH JUST A SLIGHT CHANCE OF A SHOWER OR
STORM OVER OUR FAR INLAND AREAS...AND THAT THREAT WILL BE ENDING
FAIRLY EARLY. WILL BE A WARM AND HUMID OVERNIGHT PERIOD WITH
STEADY SOUTHWEST FLOW OFF THE GULF OF MEXICO. LATE AT NIGHT WILL
SEE A FRONTAL BOUNDARY SAGGING SOUTHWARD ACROSS AL/GA. THE LOW
LEVEL FLOW AHEAD OF THIS BOUNDARY OVER THE NORTHEAST GULF BETWEEN
1000-850MB BECOMES SLIGHTLY CONVERGENT IN NATURE USING STREAMLINE
ANALYSIS. USUALLY SPEAKING IT DOES NOT TAKE MUCH IN THE WAY OF
FORCING/TRIGGER WITHIN SW FLOW TO GET SOME SHOWERS GOING OVER THE
WATER. THEREFORE WOULD EXPECT THIS LOWER LEVEL FOCUS TO SUPPORT
THE DEVELOPMENT OF A FEW SCT SHOWERS AND PERHAPS A THUNDERSTORM
AFTER MIDNIGHT...THAT WOULD THEN TRANSLATE TOWARD THE NATURE
COAST LATE AT NIGHT. MAY EVEN SEE A FEW SHOWERS AS FAR SOUTH AS
THE TAMPA BAY AREA TOWARD DAWN. WILL HAVE LOW END CHANCE POPS FOR
THE NATURE COAST AND NORTHERN MARINE ZONES...AND A SLIGHT CHANCE
20% POP FURTHER SOUTH TO TAMPA BAY.

SUNDAY...
SURFACE FRONT SETTLES DOWN TOWARD THE I-10 CORRIDOR BY LATE IN THE
DAY. THIS BOUNDARY ALONG WITH SOME SUBTLE UPPER LEVEL SHORTWAVE
ENERGY PASSING THROUGH THE SOUTHEAST CONUS SUGGESTS THE BEST RAIN
CHANCES...IN THE FORM OF SCT SHOWERS / ISOLATED STORMS WILL EXIST
TO THE NORTH OF THE I-4 CORRIDOR. FURTHER SOUTH WHERE THERE WILL
BE LITTLE TO NO SYNOPTIC FORCING FOR LIFT...IT WOULD TAKE THE
SEA-BREEZE TO FORCE CONVECTION...AND EXPECTING THE STRONG
SOUTHWEST FLOW IN THE BL TO PREVENT MUCH OF A DEFINED SEA-BREEZE
FROM FORMING. SO...FORECAST WILL FEATURE CHANCE 30-50% POPS WITH
MOSTLY CLOUDY SKIES NORTH OF THE I-4 CORRIDOR AND SLIGHT CHANCE
20% POPS AND PARTLY CLOUDY FURTHER SOUTH TO AROUND SARASOTA.
FINALLY WILL KEEP RAIN MENTION OUT OF THE FORECAST FOR THE FAR
SOUTH AROUND FORT MYERS. THIS FAR SOUTHERN ZONES WILL HAVE TO WAIT
UNTIL MONDAY...WHEN THE FRONT IS IN CLOSER PROXIMITY...TO SEE
THEIR SHOWER/STORM CHANCES INCREASE.

&&

.LONG TERM (MONDAY THROUGH NEXT SATURDAY)...
AN UPPER LOW INITIALLY NEAR THE FOUR CORNERS AREA TRACKS EAST
THROUGH TUE WITH ZONAL FLOW ALOFT THE GULF REGION...ALLOWING A
FRONTAL BOUNDARY TO MEANDER WEST TO EAST ACROSS FL AND THE
ADJACENT WATERS. BY LATE TUE OR EARLY WED THE UPPER LOW/TROUGH HAS
REACHED THE MISSISSIPPI VALLEY AND SAGGED SOUTH INTO THE GULF...
FORMING A SURFACE LOW IN THE CENTRAL GULF OR GULF COAST. THESE TWO
FEATURES MOVE EAST...WITH A COLD FRONT TRAILING THE SURFACE LOW...
ACROSS THE LOWER EASTERN SEABOARD AND OUT OVER THE ATLANTIC DURING
THU OR EARLY FRI. FOR THE END OF THE PERIOD DEEP LAYER RIDGING
BUILDS IN THE MID CONUS AND BEGINS TO WORK EAST.

THE GLOBAL MODELS CONTINUE IS HAVE DIFFERING SOLUTIONS AND ARE
SUSPECTED OF OVER DOING SOME ELEMENTS. THE ECMWF IS MORE
ROBUST...FASTER...AND WITH A MORE NORTHERLY TRACK THAN THE GFS. IN
ANY CASE THE FORECAST THINKING IS FOR A MOIST TO WET EARLY AND MID
WEEK THEN DRYING OUT GOING TOWARD THE WEEKEND. THE HIGHEST COVERAGE
AND BEST ODDS OF STRONG STORMS AND SOME FLOODING WILL BE TUE INTO
WED. TEMPERATURES NEAR TO ABOVE NORMAL WILL DROP TO NEAR NORMAL BY
THE WEEKEND...THANKS IN PART TO CLOUD COVER...RAINFALL...AND DRIER
COOLER AIR MOVING IN BY THE END OF THE WEEK.

&&

.AVIATION...
SEA BREEZE BOUNDARY HAS PUSHED WELL INLAND LEAVING ALL THE
TERMINALS OF WEST CENTRAL AND SOUTHWEST FLORIDA WITH PREVAILING
VFR CONDITIONS AND LITTLE TO NO CHANCE OF RAIN THE REMAINDER OF
THE DAY. WINDS WILL BE STEADY AND GUSTY AT TIMES FROM THE
SOUTHWEST...WITH THE WINDS BECOME LESS GUSTY AFTER SUNSET. A
BRIEF PERIOD OF MVFR CIGS WILL BE POSSIBLE FOR KSRQ/KPIE/KTPA AND
KLAL EARLY SUNDAY MORNING...HOWEVER POTENTIAL IS LOW ENOUGH AT
THIS POINT TO LEAVE MENTION OUT OF THE CURRENT TAF PACKAGE.

&&

.MARINE...
THE GRADIENT TIGHTENS TODAY ACROSS THE EASTERN GULF OF MEXICO
BETWEEN LOW PRESSURE PASSING TO OUR NORTH AND A RIDGE OF HIGH
PRESSURE THROUGH THE FLORIDA STRAITS. THE GRADIENT WILL BE
TIGHTEST TO THE NORTH OF ENGLEWOOD WHERE CAUTIONARY LEVEL WINDS
ARE EXPECTED TO DEVELOP TONIGHT INTO EARLY SUNDAY MORNING. WINDS
AND SEAS WILL CONTINUE TO FLIRT WITH CAUTIONARY LEVELS THROUGH THE
DAY ON SUNDAY AS A FRONT SLOWLY APPROACHES FROM THE NORTH. THIS
FRONT WILL LIKELY DROP INTO THE NORTHEAST GULF OF MEXICO AND STALL
DURING THE EARLY PORTION OF NEXT WEEK.

&&

.FIRE WEATHER...
SOUTH TO SOUTHWEST WINDS ACROSS WEST CENTRAL AND SOUTHWEST FLORIDA
WILL CONTINUE THROUGH SUNDAY BETWEEN HIGH PRESSURE TO OUR SOUTH AND
A FRONTAL BOUNDARY SINKING SOUTH AND EVENTUALLY STALLING ACROSS
NORTH FLORIDA DURING SUNDAY. WILL SEE AN INCREASING CHANCE OF SHOWERS
AND THUNDERSTORMS ON SUNDAY MAINLY NORTH OF THE I-4 CORRIDOR. AS THIS
FRONT SINKS FURTHER SOUTH INTO THE STATE ON MONDAY...BETTER RAIN
CHANCES WILL ALSO EXPAND SOUTH TO INCLUDE THE REMAINDER OF WEST
CENTRAL AND SOUTHWEST FLORIDA. RELATIVE HUMIDITY VALUES WILL
REMAIN WELL ABOVE CRITICAL LEVELS THROUGH THE EARLY PORTION OF
NEXT WEEK AND OTHER THAN HIGH DISPERSION INDICES SUNDAY
AFTERNOON...NO SIGNIFICANT FIRE WEATHER CONCERNS ARE ANTICIPATED.

FOG POTENTIAL...A FEW AREAS OF LATE NIGHT FOG ARE POSSIBLE TONIGHT
AWAY FROM THE IMMEDIATE COAST...HOWEVER NO SIGNIFICANT FOG IS
EXPECTED THROUGH THE WEEKEND.

&&

.PRELIMINARY POINT TEMPS/POPS...
TPA  77  86  76  83 /  10  30  40  50
FMY  76  90  77  91 /   0  10  10  40
GIF  73  88  73  86 /   0  20  40  50
SRQ  77  84  76  85 /   0  20  40  50
BKV  71  87  70  85 /  20  30  40  50
SPG  77  85  76  83 /  10  20  40  50

&&

.TBW WATCHES/WARNINGS/ADVISORIES...
FL...BEACH HAZARDS STATEMENT THROUGH SUNDAY EVENING FOR COASTAL
     CHARLOTTE-COASTAL LEE-COASTAL MANATEE-COASTAL
     SARASOTA-PINELLAS.

GULF WATERS...NONE.

&&

$$

SHORT TERM/AVIATION/MARINE/FIRE WEATHER...14/MROCZKA
LONG TERM...09/RUDE
DECISION SUPPORT...09/RUDE


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