Area Forecast Discussion
Issued by NWS Tampa Bay Area, FL

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FXUS62 KTBW 030922
AFDTBW

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE TAMPA BAY RUSKIN FL
522 AM EDT WED JUN 3 2015

.SYNOPSIS...
09Z WATER VAPOR AND H4 RAP ANALYSIS CONTINUES TO SHOW A LONGWAVE
TROUGH IN PLACE OVER THE SOUTHEASTERN CONUS...WITH DEEP CYCLONIC
FLOW OVER THE FLORIDA PENINSULA. ALTHOUGH WATER VAPOR IS SHOWING
SOME HIGH LEVEL DRYING BEGINNING TO OVERSPREAD THE REGION...IN THE
LOWER AND MIDDLE LEVELS THERE IS STILL PLENTY OF AVAILABLE
MOISTURE. REGIONAL RADARS SHOWING A "MESSY" SITUATION THIS MORNING
WITH SEVERAL AREAS OF LIGHT SHOWERS/DRIZZLE MIGRATING ACROSS THE
REGION. THE CONTINUING DEVELOPMENT OF LIGHT SHOWERS IS NOT
UNEXPECTED TAKING INTO ACCOUNT THE MOIST COLUMN AND SIGNIFICANT
CYCLONIC FLOW (IN JUNE) TO AID IN ASCENT. THEREFORE...HAVE CHANCE
POPS REGION-WIDE TO START OUT THE MORNING. HOWEVER...MOST SPOTS
WILL ONLY SEE SOME VERY LIGHT RAIN AND/OR POCKETS OF DRIZZLE. A
MORE SOLID AREA OF LIGHT RAIN IS PIVOTING NORTHWARD FROM
HARDEE/DESOTA/HIGHLANDS COUNTIES INTO SOUTHERN POLK. THESE AREAS
WILL BE THE WET ZONES FOR THE NEXT SEVERAL HOURS. THIS POCKET OF
MORE STEADY RAIN SEEMS TO BE SUPPORTED BY A WEAK ISENTROPIC
UPGLIDE REGIME AND THE CYCLONIC FLOW ALOFT. RAP FORECAST SHOWS
THIS UPGLIDE REGIME BECOMING ILL-DEFINED THROUGH THE MORNING...SO
HOPEFULLY THIS WILL HELP TO DISSIPATE THESE SHOWERS.

AT THE SURFACE WE SEE A WEAK SURFACE TROUGH OVER THE SOUTHEAST
GULF OF MEXICO AND SOUTHERN FLORIDA PENINSULA. THE TROUGH LOOKS TO
REMAIN GENERALLY IN PLACE THE NEXT DAY OR TWO...AND THIS WILL
RESULT IN MUCH OF OUR ZONES SEEING A LOW LEVEL FLOW FROM THE EAST
OR NORTHEAST.

&&

.SHORT TERM (TODAY THROUGH THURSDAY)...
WE WILL SLOWLY SEE THE MID/UPPER TROUGH AXIS SHIFT EAST AND
NORTHEAST THROUGH THE DAY. THE AXIS WILL PASS BY MIDDAY AROUND
H5...BUT WILL TAKE UNTIL THIS EVENING TO PASS FURTHER ALOFT.
STILL...A SLOW DECREASE IN THE AMOUNT OF DEEP LAYER CYCLONIC
FLOW...AND INCREASING AMOUNTS OF DRY AIR ADVECTION ABOVE 10KFT
SHOULD HELP TO DRY OUT ANY LINGERING SYNOPTIC SUPPORTED SHOWERS.
WILL ALSO GO FROM MOSTLY CLOUDY AT MOST SPOTS TO MORE AND MORE
BREAKS OF SUN AS THE DAY PROGRESSES. LATER IN THE DAY...A
SCATTERING OF SEA-BREEZE SHOWERS & STORMS WILL ATTEMPT TO DEVELOP.
IT WILL BE A BATTLE BETWEEN THESE STORMS TRYING TO DEVELOP AND THE
DRIER AIR ARRIVING ALOFT. CURRENT FORECAST HAS 30-40% POPS AT MOST
LOCATIONS LATER THIS AFTERNOON/EARLY EVENING...BUT THIS MAY HAVE
TO BE TRIMMED BACK IF THE DRY AIR ADVECTION ENDS UP MORE
AGGRESSIVE.

THE MID/UPPER LEVEL FLOW BECOMES INCREASINGLY ZONAL IN NATURE AS
WE HEAD THROUGH TONIGHT AND INTO THE DAY ON THURSDAY. SHOULD SEE A
MUCH DRIER OVERNIGHT AND THURSDAY MORNING TIME PERIOD COMPARED TO
EARLY THIS MORNING...UNDER PARTLY CLOUDY SKIES. ONCE AGAIN
THURSDAY AFTERNOON AND EVENING WILL SEE STORMS TRYING TO FORM
ALONG THE SEA-BREEZE BUT STRUGGLING TO GROW INTO THE DRY AIR
ALOFT. THE AMOUNT OF DRY AIR WOULD SEEM TO BE ENOUGH TO REALLY
DECREASE THE COVERAGE OF STORMS...BUT WITH A FAVORABLE EASTERLY
FLOW REGIME...WILL GIVE A FEW STORMS THE BENEFIT OF THE DOUBT...SO
TO SPEAK...AND FORECAST WIDELY SCATTERED DIURNAL CONVECTION ON
THURSDAY.

&&

.LONG TERM (THURSDAY NIGHT - TUESDAY)...
AT THE START OF THE LONG TERM PERIOD...A SPLIT FLOW UPPER LEVEL
PATTERN WILL FEATURE A PERSISTENT CUT-OFF LOW/TROUGH OVER THE
SOUTHEASTERN CONUS WITH WEAK RIDGING OVER THE SOUTHERN PLAINS AND
WESTERN ATLANTIC. THESE FEATURES WILL GENERALLY HOLD IN PLACE
THROUGH EARLY NEXT WEEK UNTIL A DEEPER LONG WAVE TROUGH SWEEPS INTO
THE GREAT LAKES AND MIDWEST AND FINALLY WASHES OUT THE SOUTHERN
STREAM PATTERN. AT THE SURFACE...THE SUBTROPICAL RIDGE WILL BE
POSITIONED WELL EAST OF FLORIDA OVER THE OPEN ATLANTIC...DISRUPTED
BY AN INVERTED TROUGH THAT IS FORECAST TO BE JUST OFF THE CAROLINA
COAST THURSDAY EVENING...AND WILL TRAVEL NORTH ALONG THE GULF STREAM
THROUGH THE FIRST HALF OF THE WEEKEND. WEAK GENERALLY EASTERLY TO
SOUTHEASTERLY LOW LEVEL FLOW WILL ALLOW FOR SEA BREEZES TO DEVELOP
EACH AFTERNOON THROUGH MONDAY. THESE SEA BREEZE BOUNDARIES WILL BE
ABLE TO UTILIZE AMPLE MOISTURE (PRECIPITABLE WATER VALUES OF 1.5
INCHES OR MORE FROM INTERSTATE 4 SOUTHWARD) TO PRODUCE SCATTERED
SHOWERS AND THUNDERSTORMS ACROSS THE AREA EACH AFTERNOON AND EARLY
EVENING...GRADUALLY TAPERING OFF OVERNIGHT. BY TUESDAY...THE
SUBTROPICAL SURFACE RIDGE WILL BUILD BACK INTO THE REGION WITH THE
RIDGE AXIS POSITIONED JUST NORTH OF FLORIDA...RESULTING IN SOUTHERLY
FLOW. THIS WILL BRING A BOOST IN ATMOSPHERIC COLUMN MOISTURE...WITH
PRECIPITABLE WATER VALUES OF UP TO 2 INCHES...AND NUMEROUS
THUNDERSTORMS EXPECTED OVER THE INTERIOR TUESDAY AFTERNOON.

TEMPERATURES WILL REMAIN NEAR TO A COUPLE OF DEGREES ABOVE
NORMAL...WITH HIGHS IN THE UPPER 80S AND LOW 90S...AND LOWS RANGING
FROM THE UPPER 60S TO UPPER 70S.

&&

.AVIATION...
GENERAL VFR CONDITIONS BEING OBSERVED ACROSS WEST-CENTRAL AND
SOUTHWEST FLORIDA EARLY THIS MORNING UNDERNEATH A BKN-OVC MID
LEVEL CLOUD DECK. IF THIS MID-LEVEL DECK CAN HOLD THROUGH
SUNRISE...AND BELIEVE IT WILL...THEN IT SHOULD PREVENT ANY
SIGNIFICANT CIG/VIS ISSUES. BEST SHOWER CHANCES THIS MORNING WILL
BE ACROSS SOUTHWEST FLORIDA...WITH ALL TERMINALS SEEING THE RISK
FOR A BRIEF THUNDERSTORM LATER IN THE AFTERNOON/EVENING.

&&

.MARINE...
A WEAK SURFACE TROUGH WILL REMAIN IN PLACE OVER THE SOUTHEAST GULF
OF MEXICO THROUGH THE NEXT SEVERAL DAYS. OVERALL THE GRADIENT FOR
OUR FORECAST WATER TO THE NORTH OF THIS TROUGH WILL BE WEAK AND
WINDS AND SEAS ARE EXPECTED TO BE LOW INTO THE UPCOMING WEEKEND.

&&

.FIRE WEATHER...
A WEAK GRADIENT WILL PROVIDE LIGHT WINDS TO THE REGION TODAY.
RELATIVE HUMIDITY VALUES WILL REMAIN WELL ABOVE CRITICAL LEVELS
THE NEXT SEVERAL DAYS PREVENTING ANY SIGNIFICANT FIRE WEATHER
CONCERNS.

FOG IMPACT...NO SIGNIFICANT FOG IS EXPECTED THROUGH AT LEAST
THURSDAY.

&&

.PRELIMINARY POINT TEMPS/POPS...
TPA  88  74  91  75 /  40  20  30  30
FMY  88  72  91  74 /  60  20  40  30
GIF  89  71  91  73 /  30  20  40  20
SRQ  86  72  88  74 /  30  20  20  30
BKV  89  69  91  70 /  30  30  30  30
SPG  87  75  90  77 /  40  20  20  30

&&

.TBW WATCHES/WARNINGS/ADVISORIES...
FL...NONE.
GULF WATERS...NONE.
&&

$$

SHORT TERM/AVIATION/MARINE/FIRE WEATHER...14/MROCZKA
LONG TERM...18/FLEMING
DECISION SUPPORT...18/FLEMING


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