Area Forecast Discussion
Issued by NWS Tampa Bay Area, FL

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FXUS62 KTBW 040745
AFDTBW

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE TAMPA BAY RUSKIN FL
345 AM EDT WED MAY 4 2016

.SHORT TERM (TODAY - THURSDAY)...
THE FORECAST PROCESS STARTS OUT THIS MORNING WITH A BIT OF A
MIXED SIGNAL. WHILE VIRTUALLY ALL AVAILABLE MODEL GUIDANCE SHOWED
THAT BY 06Z...SIGNIFICANT CONVECTION WOULD BE ONGOING OVER THE
NORTHERN PORTIONS OF THE THE WARNING AREA AHEAD OF AN APPROACHING
COLD FRONT...WHEN 06Z CAME AROUND...CLEAR SKIES WERE BEING
OBSERVED INSTEAD OF SHOWERS AND THUNDERSTORMS. EVEN NOW AS THE
RADAR IS FINALLY INDICATING SHOWERS ARE DEVELOPING OVER THE LOOP
CURRENT AND PUSHING EAST TOWARDS THE FLORIDA PENINSULA...GOES
WATER VAPOR SATELLITE IMAGERY IS SHOWING THAT A LARGE SWATH OF DRY
MID LEVEL AIR IS POSITIONED ALONG THE FRONTAL BOUNDARY EXTENDING
FROM NORTHERN FLORIDA THROUGH THE NORTHWESTERN GULF.
NEVERTHELESS...BETTER MOISTURE TO THE SOUTH OF THIS DRY AIR AND
STRONG DIFFLUENCE ALOFT WILL MAKE SHOWERS AND STORMS HARD TO AVOID
BY LATER THIS MORNING. SO DESPITE THE SLOW START TO THE RAIN
EVENT...WIDESPREAD SHOWERS AND THUNDERSTORMS ARE STILL EXPECTED
TODAY...WITH NEARLY 100 PERCENT CHANCES FOR RAIN AT ANY POINT IN
THE WARNING AREA BY THIS EVENING. WITH 500 MB TEMPERATURES AROUND
-11C AND MODERATE SHEAR VALUES...THE POTENTIAL EXISTS FOR A FEW
STRONGER THUNDERSTORMS TODAY...WITH DAMAGING WIND GUSTS AND HEAVY
RAIN THE MOST LIKELY HAZARDS.

ANY REMAINING THUNDERSTORM ACTIVITY SHOULD BE WINDING DOWN BY SHORTLY
AFTER SUNSET TONIGHT AS THE FRONT PASSES INTO SOUTH FLORIDA. A
COOLER AND DRIER AIRMASS WILL FILL IN...WITH LOWS TONIGHT FORECAST
TO FALL INTO THE UPPER 50S AND 60S. THURSDAY WILL BE FAIRLY
BREEZY...BUT OTHERWISE PLEASANT...WITH NOTICEABLY LOWER HUMIDITY AND
HIGH TEMPERATURES IN THE UPPER 70S AND LOW 80S.

.MID/LONG TERM (THURSDAY NIGHT-TUESDAY)...
DRY MILD CONDITIONS EXPECTED DURING THE MID/LONG TERM PERIOD.
HIGH AMPLITUDE U/L BLOCKING PATTERN WILL PERSIST WITH CUT-OFF LOWS
ALONG EAST COAST AND STRONG RIDGING THROUGH THE CENTRAL PART OF THE
COUNTRY.  DEEP EAST COAST U/L LOW WITH ANOMALOUSLY LOW HEIGHTS OVER
THE MID ATLANTIC AND FLORIDA WILL GRADUALLY LIFT NORTH FRIDAY AND
SATURDAY...AND WILL BE CAPTURED BY A NORTHERN STREAM DISTURBANCE
WHICH WILL PUSH ACROSS THE GREAT LAKES SATURDAY NIGHT AND SUNDAY
CAUSING THE EAST COAST LOW TO OPEN UP AND MOVE OVER THE WESTERN
ATLANTIC.  U/L RIDGING IN ITS WAKE OVER THE GULF OF MEXICO AND LOWER
MISSISSIPPI VALLEY WILL ALLOW HEIGHTS TO BUILD SIGNIFICANTLY OVER
THE FLORIDA PENINSULA WITH INCREASING SUBSIDENCE OVER THE FORECAST
AREA.

THE WEST COAST SYSTEM WILL GRADUALLY PUSH EAST OVER THE GREAT BASIN
OVER THE WEEKEND...AND OVER THE CENTRAL PLAINS EARLY NEXT WEEK. THIS
SYSTEM WILL FINALLY BE PICKED UP BY A STRONG NORTHERN STREAM
DISTURBANCE OVER CENTRAL CANADA DURING THE MIDDLE OF NEXT WEEK
CAUSING THE LOW TO OPEN UP WITH AN U/L TROUGH EXTENDING THROUGH THE
MISSISSIPPI VALLEY.  THE U/L RIDGE OVER THE GULF OF MEXICO AND
FLORIDA WILL HOLD OVER THE REGION MONDAY AND TUESDAY.

AT THE SURFACE...A SECONDARY COLD FRONT WILL PUSH SOUTH OF THE
FORECAST AREA THURSDAY NIGHT WITH UNSEASONABLY DRIER COOLER AIR
ADVECTING ACROSS THE REGION.  THIS MAY BE THE LAST SHOT OF COOLISH
WEATHER BEFORE THE HEAT OF SUMMER BEGINS TO SET IN.  SURFACE HIGH
PRESSURE WILL BUILD OVER THE LOWER MISSISSIPPI VALLEY AND FLORIDA IN
THE WAKE OF THE COLD FRONT FRIDAY WITH TEMPERATURES ABOUT 10 DEGREES
BELOW CLIMATIC NORMALS...AND DEW POINTS DROPPING INTO THE MID 40S
NORTH TO THE LOWER 50S SOUTH. THE SURFACE HIGH WILL SLOWLY SLIDE
OVER THE NORTHEAST GULF OF MEXICO OVER THE WEEKEND WITH TEMPERATURES
MODERATING SEVERAL DEGREES EACH DAY.  THE SURFACE HIGH WILL SHIFT
EAST OF FLORIDA EARLY NEXT WEEK WITH BOUNDARY LAYER WINDS BECOMING
EAST TO SOUTHEAST ALLOWING L/L MOISTURE TO INCREASE WITH DEW POINTS
CLIMBING BACK INTO THE 60S.

&&

.AVIATION...
MOSTLY VFR CONDITIONS ARE PERSISTING SO FAR EARLY THIS
MORNING...THOUGH OCCASIONAL MVFR OR BRIEF IFR CEILINGS AND
VISIBILITIES HAVE BEEN BREAKING THROUGH. THROUGH
SUNRISE...INCREASING ATMOSPHERIC MOISTURE IS EXPECTED TO RESULT
IN MORE WIDESPREAD MVFR CEILINGS...WITH ISOLATED POCKETS OF IFR.
WIDESPREAD THUNDERSTORMS ARE FORECAST TO DEVELOP AND MOVE INTO THE
AREA THROUGH THE REST OF THE MORNING AND TRAVEL SOUTH THROUGHOUT
THE DAY BEFORE EXITING THIS EVENING...WITH EXTENDED PERIODS OF
REDUCED FLIGHT CATEGORIES EXPECTED.

&&

.MARINE...
AN APPROACHING COLD FRONT WILL MOVE THROUGH THE COASTAL WATERS TODAY
WITH WIDESPREAD THUNDERSTORMS AND BUILDING WINDS AND SEAS. BEHIND
THE FRONT NORTHWEST WINDS ARE EXPECTED TO REACH SMALL CRAFT EXERCISE
CAUTION LEVELS AND WILL AT TIMES APPROACH ADVISORY THRESHOLDS
THROUGH THURSDAY EVENING. CONDITIONS WILL IMPROVE ON FRIDAY AS HIGH
PRESSURE BUILDS IN FROM THE NORTHWEST.

&&

.FIRE WEATHER...
WIDESPREAD THUNDERSTORMS WILL MOVE THROUGH TODAY ASSOCIATED WITH A
PASSING COLD FRONT. DRIER AIR WILL FILL IN BEHIND THE FRONT...WITH
RELATIVE HUMIDITY PERCENTAGES DROPPING INTO THE MID TO UPPER 30S ON
THURSDAY AND FRIDAY AFTERNOONS...AND LOW 30S AND UPPER 20S SATURDAY
AFTERNOON. BREEZY WINDS THURSDAY COULD CONTRIBUTE TO LOCALIZED RED
FLAG CONDITIONS...WHILE SEVERAL HOURS OF LOW RH ON SATURDAY COULD
TRIGGER A RED FLAG WARNING FOR COUNTIES THAT SEE ERC VALUES CLIMBING
TO 37 OR HIGHER.

&&

.PRELIMINARY POINT TEMPS/POPS...
TPA  79  67  78  61 / 100  10  10   0
FMY  82  68  84  61 / 100  50  10  10
GIF  79  63  78  57 / 100  20  10   0
SRQ  79  69  80  61 / 100  20  10   0
BKV  80  61  77  51 /  90  10  10   0
SPG  79  69  78  64 / 100  10  10   0

&&

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

$$

SHORT TERM/AVIATION/MARINE/FIRE WEATHER...18/FLEMING
MID TERM/LONG TERM/DECISION SUPPORT...13/OGLESBY



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