Area Forecast Discussion
Issued by NWS Tampa Bay Area, FL

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000
FXUS62 KTBW 301554
AFDTBW

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE TAMPA BAY RUSKIN FL
1154 AM EDT SAT APR 30 2016

.SYNOPSIS...
15Z WATER VAPOR AND H4 RAP ANALYSIS SHOWS A COMPLEX UPPER LEVEL
PATTERN OVER THE CONUS...HIGHLIGHTED BY LONGWAVE TROUGHING OVER THE
INTER-MOUNTAIN WEST AND CENTRAL PLAINS. WITHIN THIS TROUGH WE FIND
SEVERAL DISTINCT LOBES OF ENERGY/CLOSED LOWS...ONE EJECTING
THROUGH THE CENTRAL PLAINS BRINGING ABUNDANT RAIN/STORMS FROM THE
UPPER WEST TO THE MS VALLEY...AND A SECOND PIVOTING THROUGH THE
FOUR-CORNERS REGION. DOWNSTREAM FROM ALL THIS INCLEMENT
ACTIVITY...THE FLOW RIDGES UP OVER MUCH OF THE EASTERN
SEABOARD...INCLUDING THE FLORIDA PENINSULA. WV IMAGERY DOES SHOW
PLENTY OF HIGH LEVEL MOISTURE ARRIVING OVER THE EASTERN GULF/FL
PENINSULA ALONG THE NOSE OF A SOUTHERN STREAM JETSTREAK. THESE
CLOUDS ARE GENERALLY ABOVE 20-25KFT...AND WILL CONTINUE TO FILTER
THE SUN AT TIMES THROUGH THE REMAINDER OF THE DAY.

DROP BELOW THIS CIRRUS LEVEL AND THE COLUMN OVER THE PENINSULA IS
GENERALLY QUITE DRY. THIS WAS SHOWN NICELY IN THE 30/12Z KTBW
SOUNDING PROFILE. THE SUBSIDENCE INVERSION ASSOCIATED WITH THE RIDGE
OVERHEAD WAS SAMPLED IN THE VICINITY OF 700MB...WITH A MARKED DROP
IN DEWPOINT/RH ABOVE THIS LEVEL.

AT THE SURFACE...HIGH PRESSURE CONTINUES TO RIDGE BACK ACROSS THE
FLORIDA PENINSULA FROM THE WESTERN ATLANTIC. THE PRESSURE GRADIENT
AROUND THIS RIDGE IS PROVIDING A GENERALLY LIGHT SOUTHEAST
SYNOPTIC FLOW. DESPITE THE ABUNDANT HIGH CLOUDS...WE ARE STILL
EXPERIENCING SUFFICIENT INSOLATION FOR A DECENT TEMPERATURE RISE.
MOST SPOTS ARE NOW INTO THE LOWER 80S AS OF THE WRITING OF THIS
DISCUSSION. A LITTLE FURTHER TEMP RISE AND WE SHOULD BEGIN TO SEE
OUR WINDS VEER ONSHORE NEAR THE COAST WITH SEA- BREEZE
DEVELOPMENT. THIS TURNING SHOULD COMMENCE BETWEEN 16-18Z.

&&

.SHORT TERM (REST OF TODAY THROUGH SUNDAY)...
THE WEATHER WILL CONTINUE WARM AND BENIGN ACROSS THE FORECAST AREA
FOR THE NEXT FEW HOURS...AS WE WAIT FOR THE SEA-BREEZE TO DEVELOP.
ONCE THE SEA-BREEZE BEGINS TO MAKE SOME PROGRESS INLAND...THE
POTENTIAL FOR ISOLATED SHOWERS TO DEVELOP WILL INCREASE. MOST SPOTS
WILL BE DRY TODAY...ESPECIALLY THE FURTHER SOUTH FROM THE I-4
CORRIDOR ONE TRAVELS. THE DRY AIR AND SUPPRESSION ARE DEEPEST AND
STRONGEST OVER THE SOUTHERN HALF OF THE PENINSULA...AND ANY
CONVECTION THAT DOES DEVELOP SHOULD BE QUITE ISOLATED AND BRIEF IN
NATURE. THE ATMOSPHERIC COLUMN IS SLIGHTLY "MORE FAVORABLE" NORTH OF
I-4...BUT "MORE FAVORABLE" IS STILL NOT FAVORABLE. THERE IS
PLENTY OF DRY AIR OVER OUR NORTHERN ZONES FOR UPDRAFTS TO BATTLE.
STILL THE POTENTIAL FOR A FEW SUSTAINED UPDRAFTS TO THE NORTH AND
EAST OF THE TAMPA BAY AREA DOES EXIST AS WE HEAD DEEPER INTO THE
AFTERNOON/EARLY EVENING...AND CONVERGENCE BETWEEN THE EAST COAST
AND WEST COAST SEA-BREEZE CIRCULATIONS IS AT A MAXIMUM. THE
POTENTIAL WILL ALSO SHIFT INLAND QUICKLY WITH THE PROGRESSION OF
THE WEST COAST SEA-BREEZE. HAVE GONE WITH A 20-30% POP OVER THE
NORTHERN HALF OF THE AREA...ALTHOUGH ALONG THE COAST...THE RAIN
CHANCES ONLY BRIEFLY OCCUR...AND THEN DECREASE AFTER MID-
AFTERNOON BEHIND THE SEA- BREEZE.

TONIGHT...FEW ISOLATED MID EVENING SHOWERS ALONG AND NORTH OF THE
I-4 CORRIDOR SHOULD DISSIPATE WITHIN A COUPLE HOUR OF SUNSET...AND
SET UP A DRY AND SEASONABLY WARM OVERNIGHT PERIOD. WINDS WILL
RETURN TO THE SOUTHEAST AS THE SEA-BREEZE SHUTS DOWN AND BECOME
LIGHT BY LATE EVENING.

SUNDAY... MORE OF THE SAME FOR THE SECOND HALF OF THE WEEKEND.
ALTHOUGH THE UPPER RIDGE AXIS SHIFT A BIT TO THE EAST...OVERALL
THE SYNOPTIC SETUP IS VERY SIMILAR TOMORROW. PLENTY OF DRY MID-
LEVEL AIR TO CONTEND WITH...WITH THE GREATEST SUPPRESSION AND MOST
HOSTILE ENVIRONMENT TOWARD DEEP CONVECTION EXISTING OVER THE
SOUTHERN HALF OF THE FORECAST AREA. WITH THE NOSE OF THE SOUTHERN
STREAM JET NEARBY...WOULD ANTICIPATE BOUTS OF HIGH LEVEL CIRRUS
CONTINUING TO INVADE OUR SKIES AND FILTER THE SUN FROM TIME TO
TIME. FOR THAT REASON...WILL CALL IT A MIX OF SUN AND CLOUDS. ONCE
THE SEA-BREEZE FORMS...A FEW ISOLATED SHOWERS CAN BE EXPECTED AWAY
FROM THE COAST...MAINLY NORTH OF THE I-4 CORRIDOR.
HOWEVER...COVERAGE OF ANY SHOWERS WILL NOT BE GREAT AND SHOULD
HAVE LIMITED (IF ANY) IMPACT TO PLANNED OUTDOOR ACTIVITIES.

&&

.AVIATION...
VFR CONDITIONS PREVAIL ACROSS WEST-CENTRAL AND SOUTHWEST FLORIDA.
JUST A SLIGHT CHANCE OF A BRIEF SHOWER OR STORM AT KLAL AFTER
20Z. LIGHT WINDS SHIFT SOUTHWEST WITH THE SEA- BREEZE FOR
KSRQ/KPIE/KTPA THIS AFTERNOON...BEFORE SHIFTING BACK TO THE
SOUTHEAST LATE IN THE EVENING. THE BEST POTENTIAL FOR ANY PATCHY
FOG EARLY SUNDAY MORNING WILL BE NORTH OF THE I-4 CORRIDOR AND FOR
NOW WILL LEAVE ANY MENTION OF VIS RESTRICTIONS OUT OF THE FORECAST
TERMINALS.

&&

.MARINE...
A RIDGE OF WEAK HIGH PRESSURE WILL RESIDE ACROSS FLORIDA AND THE
EASTERN GULF OF MEXICO THROUGH THE EARLY PART OF THE WEEK...THEN
SLIDE EAST AS A COLD FRONT APPROACHES WEDNESDAY INTO THURSDAY. NO
SIGNIFICANT MARINE HAZARDS ARE ANTICIPATED BEFORE THE APPROACH OF
THIS MID-WEEK FRONT.

&&

.PRELIMINARY POINT TEMPS/POPS...
TPA  89  72  89  72 /  10  10   0  10
FMY  89  69  89  71 /  10   0  10   0
GIF  89  69  91  70 /  10  10  10  10
SRQ  84  70  84  70 /   0   0   0   0
BKV  89  67  88  66 /  30  20  10   0
SPG  87  72  87  74 /   0   0   0   0

&&

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

&&

$$

SYNOPSIS/SHORT TERM/AVIATION/MARINE...MROCZKA



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