Area Forecast Discussion
Issued by NWS Tampa Bay Area, FL

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FXUS62 KTBW 180802
AFDTBW

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE TAMPA BAY RUSKIN FL
400 AM EDT THU SEP 18 2014

...NUMEROUS SHOWERS RETURN TO THE FORECAST FOR FRIDAY...

.SYNOPSIS...
08Z WATER VAPOR AND H4 RAP ANALYSIS SHOWS A LONGWAVE PATTERN
CONSISTING OF RIDGING OVER MUCH OF THE INTER-MOUNTAIN WEST AND
DOWNSTREAM TROUGHING INTO THE EASTERN STATES. FLORIDA PENINSULA
RESIDES ON THE SOUTHERN PERIPHERY OF THE EASTERN CONUS TROUGH.
IMPULSES ARE MOVING FAIRLY QUICKLY THROUGH THIS PATTERN AND SO THE
FORECAST WILL BE CHANGING QUICKLY AS WELL THROUGH THE NEXT 24 TO 36
HOURS. SHORTWAVE IMPULSE IS NOW PULLING EAST OF THE REGION WITH A
SWATH OF LARGE SCALE SUBSIDENCE AND RESULTING DRY AIR ALOFT NOW
PROGRESSING OVER THE NORTHERN AND CENTRAL PORTIONS OF THE PENINSULA.
THIS MORE SUPPRESSIVE ENVIRONMENT ALLOWED MUCH OF THE REGION TO DRY
OUT DURING THE SECOND HALF OF WEDNESDAY AND CONTINUE TO SEE MAINLY
DRY CONDITIONS EARLY THIS MORNING. ONLY SHOWERS ARE OCCURRING OVER
THE FAR SOUTHERN ZONES/COASTAL WATERS WITHIN A MORE FAVORABLE
MOISTURE COLUMN AND ALONG THE LEFTOVER FRONT/SURFACE TROUGH NOW DOWN
OVER FAR SOUTHERN FL.

AS MENTIONED ABOVE...WITH THE DRIER AIR ALOFT NOW FIRMLY IN PLACE...
SKIES HAVE BECOME MOSTLY CLEAR FOR ALL BUT THE FAR SOUTHERN AREAS
AROUND KFMY. PLENTY OF GROUND MOISTURE FROM THE RAIN ON WEDNESDAY
ALONG WITH A LITTLE SUPPRESSION IS ALLOWING SOME PATCHY GROUND FOG
EARLY THIS MORNING. NOT EXPECTED A WIDESPREAD EVENT...BUT A FEW MORE
FOG PRONE SPOTS MAY BRIEFLY SEE LOWERED VISIBILITIES BEFORE SUNRISE.

&&

.SHORT TERM (TODAY THROUGH FRIDAY)...
WELL...IT CERTAINLY LOOKS AS THOUGH TODAY WILL BE THE BETTER OF THE
TWO SHORT TERM DAYS IN TERMS OF SENSIBLE WEATHER...AS NUMEROUS
SHOWERS RETURN TO THE FORECAST FOR MUCH OF THE AREA FOR FRIDAY.

STARTING OUT THE DAY HERE IN WEST-CENTRAL FLORIDA ON THE BACKSIDE OF
DEPARTING UPPER LEVEL ENERGY...WITH A SWATH OF DRY AIR AND
SUPPRESSION IN PLACE. THIS PATTERN SHOULD KEEP OUR WEATHER MOSTLY
DRY / RAIN FREE THIS MORNING. ONLY EXCEPTION WILL CONTINUE TO BE
DOWN TOWARD LEE/CHARLOTTE COUNTIES WHERE A FEW SHOWERS WILL REMAIN
POSSIBLE...ESPECIALLY CLOSE TO THE COAST. TEMPERATURES WILL RISE
FROM THE UPPER 60S AND 70S AROUND SUNRISE THROUGH THE 80S DURING THE
MORNING.

THIS AFTERNOON...AS A RESULT OF THE LIGHT GRADIENT AND TERRESTRIAL
WARMING...SHOULD SEE A SEA-BREEZE CIRCULATION DEVELOP ON BOTH COASTS
OF THE PENINSULA AND MOVE INLAND. COMING TO THE END OF THE SUMMER
CONVECTION SEASON...BUT LOOKS AS THROUGH THE SEA-BREEZE TODAY WILL
FIND A GOOD ENOUGH ENVIRONMENT TO SUPPORT A FEW SCT STORMS BY THE
LATER AFTERNOON/EARLY EVENING HOURS. THIS SHOULD ESPECIALLY BE TRUE
OVER THE SOUTHERN ZONES AND AWAY FROM THE BEACHES. WOULD BE A BIT
CONCERNED ABOUT WHETHER CONVECTION COULD BE SUSTAINED IF THE CURRENT
UPPER LEVEL ENVIRONMENT WAS GOING TO LAST...BUT LOOKS AS THOUGH WE
WILL BEGIN TO SEE THE COLUMN MOISTEN BY LATER TODAY. AFTERNOON HIGH
TEMPERATURES SHOULD REACH WITHIN A COUPLE DEGREES EITHER SIDE OF 90.

TONIGHT WILL SEE OUR NEXT "WEATHER MAKER" BEGINNING TO APPROACH FROM
THE WEST IN THE FORM OF A DECENT SHORTWAVE TROUGH DIGGING DOWN THE
BACKSIDE OF THE MAIN LONGWAVE TROUGH...AND SPREADING OUR ACROSS THE
NORTHEAST GULF OF MEXICO. AHEAD OF THIS SHORTWAVE...GFS/ECMWF SHOW A
DECENT SWATH OF DEEP LAYER SYNOPTIC SUPPORT / Q-VECTOR CONVERGENCE
OVER THE EASTERN GULF OF MEXICO. IN ADDITION...THE REGION WILL COME
INCREASINGLY UNDER AN AREA OF UPPER LEVEL DIFFLUENCE WITHIN THE
ENTRANCE REGION OF JET ENERGY ALONG THE SHORTWAVE HEIGHT GRADIENT.
THEREFORE...FOR THIS TIME OF YEAR...WE LOOK TO HAVE HEALTHY SYNOPTIC
SUPPORT FOR LIFT. THIS LIFT WILL BE ALIGNED OVER A REGION OF LOWER
LEVEL FOCUS /CONVERGENCE ASSOCIATED WITH THE SURFACE REFLECTION OF
THE ENERGY PASSING ALOFT. WITH ALL THIS IN MIND...SEE LITTLE REASON
WHY NUMEROUS SHOWERS/STORMS WILL NOT BE BREAKING OUT OVER THE
EASTERN GULF DURING THE SECOND HALF OF THE NIGHT AND PROGRESSION
TOWARD THE FL WEST COAST. WILL KEEP THE HIGHEST RAIN CHANCES OFF THE
COAST DURING THE OVERNIGHT...BU DO NOT THINK IT WILL TAKE LONG AFTER
SUNRISE TO SEE THE SHOWERS COMING ASHORE (IF IT WAITS THAT LONG).

FRIDAY IS LOOKING LIKE AN UNSETTLED AND MOSTLY CLOUDY DAY WITH
PLENTY OF SHOWER ACTIVITY. WILL NOT BE RAINING THE WHOLE DAY...BUT
OUTDOOR ACTIVITIES LOOK TO ALMOST CERTAINLY BE IMPACTED. THE SWATH
OF Q-VECTOR CONVERGENCE AND UPPER LEVEL DIFFLUENCE ARRIVE OVER THE
PENINSULA AS THE UPPER LEVEL SHORTWAVE ENERGY AMPLIFIES OVER THE
EASTERN GULF. HAVE RAIN CHANCES QUICKLY INCREASING DURING THE
MORNING HOURS AND REACHING CATEGORICAL LEVELS FOR THE SECOND HALF OF
THE DAY. BEST MOISTURE/SYNOPTIC SUPPORT WILL ALIGN OVER THE CENTRAL
AND SOUTHERN PORTIONS OF THE AREA...HOWEVER...FEEL THE GUIDANCE IS
UNDERDONE OVER THE NATURE COAST...AND HAVE ALLOWED LIKELY POPS EVEN
FOR THESE ZONES. JUST CAN NOT SEE WITH THE ENERGY ALOFT...AND THE
TIME OF YEAR...THAT WE WILL NOT SUPPORT NUMEROUS SHOWERS TO THE
NORTH OF THE I-4 CORRIDOR. WITH ALL THE CLOUDS AND
SHOWERS...TEMPERATURES SHOULD BE HELD DOWN IN THE 80S. IF THE
SHOWERS ARE NUMEROUS ENOUGH AND START EARLY ENOUGH...THEN SOME SPOTS
MAY HAVE TROUBLE GETTING OUT OF THE LOWER 80S.

&&

.LONG TERM (SATURDAY THROUGH NEXT WEDNESDAY)...
THE PERIOD BEGINS WITH AN UPPER TROUGH OVER THE SOUTHEAST U.S. AND
EASTERN GULF WHILE HIGH PRESSURE OFFSHORE NEW ENGLAND SPRAWLS
SOUTHWARD TO THE GULF AND FL...WITH AN INVERTED TROUGH EAST OF THE
STATE. DURING THE WEEKEND A SHORT WAVE TROUGH SLIDES OUT OF CANADA
TO THE GREAT LAKES REGION...DEEPENING AS IT DOES...WITH THE UPPER
TROUGH BECOMING A BROAD CLOSED LOW OVER FL...SPINNING THE SURFACE
TOUGH INTO A LOW EAST OF THE GA/FL COAST. THESE TWO FEATURES TRACK
NORTHEASTWARD TOWARD THE END OF THE WEEKEND AS THE GREAT LAKES
TROUGH BEGINS TO DROP DOWN TO THE GULF COAST.

FOR THE EARLY PART OF NEXT WEEK THE GREAT LAKES-GULF COAST TROUGH
SLIDES OUT OVER ATLANTIC COASTAL WATERS AS DEEP LAYER RIDGING
BUILDS OVER THE MISSISSIPPI RIVER VALLEY THEN MOVES EAST...PUSHING
A FRONTAL BOUNDARY ACROSS THE GULF COASTAL AND SOUTHEASTERN STATES
AND INTO THE EAST GULF AND FL.

THE TROUGHINESS OVER THE WEEKEND FOLLOWED BY THE FRONTAL BOUNDARY
SAGGING IN WILL MAINTAIN A MOIST ATMOSPHERE WITH ISOLATED TO
SCATTERED SHOWERS AND STORMS. THERE WILL BE SOME MINOR VARIATION IN
TEMPERATURES BUT WITHIN A DEGREE OR TWO OF NORMAL.

&&

.AVIATION...
PATCHY FOG HAS DEVELOPED EARLY THIS MORNING ACROSS THE INTERIOR.
HAVE SEEN PROLONGED IFR OR LOWER VISIBILITIES AT KLAL AND THIS IS
LIKELY TO CONTINUE THROUGH SUNRISE. MAY SEE A BRIEF PERIOD OF VIS
RESTRICTIONS AROUND KPGD AS WELL TOWARD DAWN. ONCE ANY EARLY MORNING
FOG BURNS OFF WILL EXPECT PREVAILING VFR CONDITIONS FOR ALL
TERMINALS THROUGH THE DAY. WILL BE A FEW STORMS AROUND TODAY...WITH
THE BEST CHANCES FROM KPGD TO KFMY/KRSW. PREVAILING VFR CONDITIONS
SHOULD CONTINUE INTO THE EVENING HOURS AWAY FROM ANY SCT STORMS.
THEREAFTER...HEADING INTO FRIDAY...NUMEROUS SHOWERS/AREAS OF RAIN
LOOK TO BE IN THE FORECAST FOR ALL TERMINALS...AND LIKELY WILL BE
ACCOMPANIED BY PERIODS OF MVFR RESTRICTIONS.

&&

.MARINE...
A WEAK FRONT IS NOW STALLED SOUTH OF THE FORECAST WATERS WITH A VERY
WEAK GRADIENT IN PLACE OVER THE EASTERN GULF OF MEXICO. THIS WILL
RESULT IN LIGHT WINDS AND SEAS OVER THE WATERS THROUGH THIS EVENING.
WINDS BECOME EASTERLY ON FRIDAY AND MAY INCREASE TO NEAR CAUTIONARY
LEVELS AT TIMES FRIDAY AFTERNOON INTO EARLY SATURDAY...ESPECIALLY TO
THE NORTH OF ENGLEWOOD. IN ADDITION...SHOWERS AND STORMS LOOK TO
ONCE AGAIN BECOME NUMEROUS IN NATURE OVERNIGHT INTO FRIDAY.

&&

.FIRE WEATHER...
NO SIGNIFICANT FIRE WEATHER CONCERNS ARE EXPECTED THROUGH THE
UPCOMING WEEKEND. RAIN CHANCES WILL BE LOWER TODAY...BUT BECOME
LIKELY ONCE AGAIN FOR FRIDAY.

PATCHY GROUND FOG THIS MORNING WILL BURN OFF WITHIN A FEW HOURS OF
SUNRISE...AND IS NOT EXPECTED TO BE REPEATED TONIGHT INTO FRIDAY
MORNING.

&&

.PRELIMINARY POINT TEMPS/POPS...
TPA  89  75  84  71 /  30  30  80  30
FMY  90  74  88  72 /  50  30  80  30
GIF  91  73  86  70 /  40  30  80  30
SRQ  89  73  87  71 /  30  30  80  30
BKV  91  71  84  67 /  30  20  70  30
SPG  89  77  84  73 /  30  30  80  30

&&

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

&&

$$

SYNOPSIS/SHORT TERM/AVIATION/MARINE/FIRE WX...MROCZKA
LONG TERM...RUDE




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