Area Forecast Discussion
Issued by NWS Tampa Bay Area, FL

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000
FXUS62 KTBW 011950
AFDTBW

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE TAMPA BAY RUSKIN FL
350 PM EDT SUN MAY 1 2016

.SYNOPSIS...
19Z WATER VAPOR AND H4 RAP ANALYSIS SHOWS A MID/UPPER LAYER
WESTERLY FLOW PATTERN IN PLACE ACROSS THE GULF OF MEXICO AND
FLORIDA PENINSULA. SOUTHERN STREAM JET CROSSES OVER NORTHERN
MEXICO AND ACROSS THE GULF...WITH THE NOSE OF THE MAIN JETSTREAK
OVER OUR REGION. NORTHERN STREAM JET IS IN FAIRLY CLOSE
PROXIMITY...CROSSING OVER THE SOUTHERN/CENTRAL PLAINS...TO THE
MID MS AND OHIO VALLEYS. 01/12Z KTBW SOUNDING PROFILE SAMPLED
THESE WINDS ALOFT WELL...SHOWING A DEEP LAYER WEST FLOW ABOVE
700MB.

AT THE SURFACE...ATLANTIC HIGH PRESSURE CONTINUES TO RIDGE BACK TO
THE WEST OVER THE FLORIDA PENINSULA AND EASTERN GULF OF MEXICO. A
COMPLEX FRONTAL SYSTEM REMAINS WELL TO OUR NORTH AND NORTHWEST
FROM SOUTHERN TEXAS TO THE LOWER MS VALLEY AND NORTHEAST INTO THE
OHIO VALLEY. CLUSTERS OF SHOWERS AND STORMS ARE FORMING AND
ONGOING IN ADVANCE OF THIS FRONT...BUT WILL ALSO REMAIN WELL
REMOVED FROM OUR FORECAST AREA. THE ONLY IMPACT FROM THESE STORMS
THAT WE MAY SEE SOME INCREASE IN HIGH CLOUDS LATER THIS EVENING OR
OVERNIGHT ACROSS THE NORTHERN NATURE COAST ZONES ASSOCIATED WITH
ANVIL BLOWOFF ADVECTING DOWNSTREAM IN THE SYNOPTIC UPPER FLOW.

SEA-BREEZE HAS FORMED ALONG THE COAST AND WE ARE NOW SEEING THE
CONVERGENCE ZONE BETWEEN THIS WEST-COAST SEA-BREEZE AND THE
FLORIDA EAST COAST SEA-BREEZE SET UP ALONG AND JUST EAST OF THE
I-75 CORRIDOR. MID-AFTERNOON VISIBLE SATELLITE IMAGERY IS SHOWING
THE CUMULUS FIELD IN THIS REGION BECOMING A BIT MORE DEFINED.
ALTHOUGH...AS OF NOW...NOT SEEING ANYTHING ON RADAR AS THESE
COLUMNS ARE SHALLOW AND STILL TRAPPED UNDERNEATH A STRONG CAPPING
SUBSIDENCE INVERSION SHOWN WELL ON THE MORNING 12Z KTBW SOUNDING.
THIS CAPPING INVERSION WILL HOLD BACK MUCH OF THE CONVECTION THIS
EVENING. HOWEVER...WHERE MOISTURE POOLING IS GREATEST ALONG THE
CONVERGING SEA-BREEZE BOUNDARIES...ML CAPE MAY BECOME SUFFICIENT
TO BRIEFLY OVERCOME THIS CAPPING LAYER AND SUPPORT ISOLATED TO
WIDELY SCT STORMS AFTER 21Z. THE LAST FEW RUNS OF THE HRRR ARE
ALREADY WAY TO AGGRESSIVE WITH CONVECTION COMPARED TO
REALITY...SO UNFORTUNATELY CAN NOT USE THIS USUALLY RELIABLE
GUIDANCE TO HELP WITH THE SHORT TERM CONVECTIVE TRENDS. FEEL THE
CURRENT FORECAST IS THE BEST COURSE OF ACTION FOR NOW. EXPECT A
FEW STORMS TO FINALLY BREAK THIS CAP WITHIN THE ZONE DESCRIBED
ABOVE...MOST LIKELY INITIATING BETWEEN 21-22Z...AND THEN LINGER
FOR A FEW HOURS THIS EVENING BEFORE DISSIPATING.

&&

.SHORT TERM (TONIGHT THROUGH MONDAY)...
TONIGHT...WITH THE LATE START TO THE ISOLATED CONVECTION...WOULD
ANTICIPATE THE CELLS THAT DO DEVELOP TO LINGERING FOR A FEW HOURS
PAST SUNSET. WILL KEEP A LOW CHANCE POP IN THE FORECAST FOR THIS
FAVORED CONVERGENCE ZONE UNTIL 03Z...AND THEN ALLOW THE REST OF
THE OVERNIGHT TO BE DRY REGION-WIDE. A FEW POCKETS OF FOG ARE
QUITE LIKELY IN THE HOURS BEFORE DAWN...BUT NEITHER THE SREF OR
STATISTICAL GUIDANCE ARE SUGGESTING WE WILL HAVE ANY SIGNIFICANT
VIS ISSUES FOR THE MORNING COMMUTE. GIVEN THAT THE COVERAGE OF
RAINFALL TODAY SHOULD BE LOW...WOULD AGREE WITH THE NWP. LOW
TEMPERATURES TONIGHT WILL BE SEASONABLY WARM WITH UPPER 60S INLAND
AND LOWER 70S ALONG THE COAST.

MONDAY...
OVERALL THE SYNOPTIC PATTERN IS NOT ALL THAT DIFFERENT FROM
TODAY. THE MOST INFLUENTIAL DIFFERENCE MAY BE THAT THE MID/UPPER
LEVEL ENVIRONMENT IS SLIGHTLY MORE MOIST AND HENCE A BIT LESS
HOSTILE TOWARD DEEP CONVECTION. ALSO...THERE DOES STILL SEEM TO BE
A HINT OF THE CAPPING INVERSION IN THE FORECAST SOUNDINGS...BUT AT
LEAST FOR NOW...IT APPEARS LESS DRAMATIC. BOTH OF THESE FACTORS
SHOULD CONTRIBUTE TO A BIT HIGHER COVERAGE OF LATE DAY STORMS
ACROSS THE SAME FAVORED CONVERGENCE ZONE RUNNING ALONG AND JUST
EAST OF THE I-75 CORRIDOR. INHERITED FORECAST HAS 30-40% POPS IN
THIS ZONE...AND THEN TAPERS RAIN CHANCES BACK TO 10-20% AT THE
COAST. BASED ON THE EXTENT OF THE 12Z GUIDANCE CYCLE...DO NOT SEE
MUCH REASON TO MAKE SIGNIFICANT CHANGES. ANY CONVECTION ON MONDAY
WILL AGAIN BE SUPPRESSED BY THE ENVIRONMENT ALOFT UNTIL LATE IN
THE AFTERNOON OR EARLY EVENING...WHICH SHOULD AGAIN ALLOW
LOCATIONS AWAY FROM THE IMMEDIATE COAST TO PUSH 90 FOR HIGH
TEMPERATURES. AT THE BEACHES TEMPS HOLD IN THE 80S WITH THE
DEVELOPMENT ONSHORE FLOW DURING THE AFTERNOON.

ENJOY YOUR SUNDAY EVENING EVERYONE!

&&

.MID/LONG TERM (TUESDAY THROUGH NEXT SUNDAY)...
A SLOW MOVING FRONTAL BOUNDARY WILL BE POSITIONED TO THE NORTH OF
THE AREA LATE MONDAY INTO TUESDAY. SOUTH OF THIS BOUNDARY...THERE
WILL BE A GRADUAL INCREASE IN LOW AND MID-LEVEL MOISTURE ACROSS
THE FLORIDA PENINSULA AS WINDS BECOME MORE SW AS SURFACE RIDGE
BEGINS TO PUSH EAST. INCREASING MOISTURE AND COOLER TEMPERATURES
ALOFT (H5 TEMPS AROUND -12C) SHOULD CREATE AN ENVIRONMENT
FAVORABLE FOR FAIRLY DECENT COVERAGE OF AFTN SHOWERS AND STORMS
ALONG SEABREEZE/BOUNDARY COLLISIONS. HIGH TEMPERATURES WILL REMAIN
WARM WITH MID TO UPPER 80S AREA WIDE.

LATE TUESDAY INTO WEDNESDAY A STRONG UPPER LEVEL LOW WILL PUSH OUT
OF THE GREAT LAKES HELPING TO INDUCE SIGNIFICANT TROUGHING ACROSS
THE EASTERN UNITED STATES FOR THE REST OF THE WEEK. AT THE SAME
TIME...ANOTHER SHORTWAVE ACROSS THE CENTRAL PLAINS IS FORECAST TO
MOVE SE INTO THE DEEP SOUTH. THIS SHORTWAVE WILL BE THE CATALYST FOR
GIVING THIS FRONT THE PUSH IT NEEDS TO CLEAR OUT OF THE SOUTHEASTERN
U.S. DEPENDING ON THE INTENSITY OF THIS SHORTWAVE...SOME STRONG TO
SEVERE THUNDERSTORM POTENTIAL MAY EXIST...THOUGH UNCERTAINTY REMAINS
AS TO THE TIMING AND INTENSITY OF BOTH SURFACE AND UPPER LEVEL
FEATURES SO STAY TUNED. EITHER WAY...SHOWERS AND THUNDERSTORMS WILL
BE LIKELY ACROSS THE AREA AS THE FRONT PUSHES THROUGH WEDNESDAY.

THE UPPER LEVEL PATTERN CONTINUES TO AMPLIFY THROUGHOUT THE REST OF
THE WEEK BEHIND THE FRONT AND COOLER...DRIER CONTINENTAL AIR WILL
FILTER IN TO THE PENINSULA BEGINNING THURSDAY AND CONTINUING THROUGH
THE WEEKEND. PLEASANT WEATHER EXPECTED THU-SAT WITH TEMPERATURES
NEAR OR SLIGHTLY BELOW NORMAL WITH NO RAIN AND LIMITED CLOUD COVER.
HIGH TEMPERATURES EXPECTED BETWEEN UPPER 70S TO LOW/MID 80S FROM
NORTH TO SOUTH WITH OVERNIGHT LOWS MID/UPPER 50S...LOW/MID 60S
CLOSER TO THE COAST. TEMPERATURES LOOK TO BEGIN MODERATING LATE IN
THE WEEKEND INTO EARLY NEXT WEEK.

&&

.AVIATION...
01/18Z CYCLE. PREVAILING VFR WITH SCT-BKN CUMULUS FIELD NOW IN
PLACE. LIGHT SE TO EAST WINDS BEGINNING TO SHIFT ONSHORE ALONG
THE COAST...AND WILL SEE THIS SHIFT REACH KPIE/KTPA IN NEXT COUPLE
OF HOURS. ISOLATED SHOWERS/STORMS ALONG THE SEA- BREEZE LATE
AFTERNOON/EARLY EVENING. BEST POTENTIAL FOR A BRIEF SHOWER BETWEEN
20-00Z FOR KPGD/KFMY/KRSW...AND ADDED VCTS TO THESE TERMINALS.
SOME POTENTIAL FOR ISOLATED STORMS TO MIGRATE CLOSER TO TAMPA BAY
TERMINALS AFTER 00Z...BUT CONFIDENCE NOT GREAT ENOUGH TO INCLUDE
IN CURRENT TAF ISSUANCE.

&&

.MARINE...
ATLANTIC HIGH PRESSURE WILL RIDGE ACROSS FLORIDA INTO
THE EASTERN GULF OF MEXICO THROUGH EARLY NEXT WEEK. THIS RIDGE
WILL SLIDE TO THE EAST AS A COLD FRONT ENTERS THE GULF AND MOVES
ACROSS THE FORECAST WATERS WEDNESDAY. WINDS SHIFT NORTH BEHIND
THIS FRONT AND MAY APPROACH ADVISORY LEVELS FOR A TIME WEDNESDAY
NIGHT INTO THURSDAY. HIGH PRESSURE THEN BUILDS OVER THE REGION BY
THE BEGINNING OF NEXT WEEKEND.

&&

.FIRE WEATHER...
HIGH PRESSURE WILL CONTINUE TO CONTROL OUR WEATHER THROUGH THE
EARLY PORTION OF THE WEEK. NO SIGNIFICANT FIRE WEATHER CONCERNS
ARE ANTICIPATED THE NEXT COUPLE OF DAYS AS RELATIVE HUMIDITY
VALUES REMAIN GENERALLY ABOVE CRITICAL LEVELS...AND WINDS REMAIN
GENERALLY LIGHT. ALTHOUGH A FEW ISOLATED TO SCATTERED SHOWERS
ARE POSSIBLE THE NEXT FEW AFTERNOONS...THE NEXT POTENTIAL FOR
WIDESPREAD WETTING RAINS WILL NOT ARRIVE UNTIL THE PASSAGE OF
A COLD FRONT SCHEDULED TO ARRIVE DURING WEDNESDAY. A MUCH DRIER
AIRMASS ARRIVES ACROSS THE STATE FOR THE END OF THE WEEK IN THE
WAKE OF THIS FRONT.

FOG POTENTIAL...PATCHY FOG POSSIBLE EARLY MONDAY MORNING AWAY
FROM THE COAST...HOWEVER NO SIGNIFICANT AREAS OF FOG OR
VISIBILITY RESTRICTIONS ARE ANTICIPATED THROUGH TUESDAY.

&&

.PRELIMINARY POINT TEMPS/POPS...
TPA  74  87  74  86 /  20  10  10  30
FMY  71  88  73  88 /  20  30  20  20
GIF  71  90  71  89 /  10  30  30  40
SRQ  72  83  72  84 /  10  10  10  20
BKV  68  88  68  87 /  20  20  20  30
SPG  74  86  75  85 /  10  10  10  30

&&

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

&&

$$

SYNOPSIS/SHORT TERM/AVIATION/MARINE/FIRE WX...MROCZKA
MID TERM/LONG TERM/DECISION SUPPORT...MCKAUGHAN



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