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657
FXUS62 KTBW 021547
AFDTBW

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE TAMPA BAY RUSKIN FL
1130 AM EDT TUE SEP 2 2014

.UPDATE (REST OF TODAY AND TONIGHT)...
15Z WATER VAPOR AND H4 RAP ANALYSIS SHOW THE MAIN NORTHERN STREAM
FLOW FAR TO OUR NORTH ALONG THE CANADIAN BORDER AND OVER TOP AN
ELONGATED WEST TO EAST ORIENTED UPPER RIDGE EXTENDING ACROSS THE
SOUTHERN TIER OF THE CONUS. OUR FORECAST AREA RESIDES UNDER THIS
LARGE UPPER RIDGE...HOWEVER A TUTT FEATURE RETROGRADING WESTWARD
OVER THE BAHAMAS IS BEGINNING TO ERODE THE RIDGE TO OUR SOUTH
AND EAST...AND WILL BEGIN TO BREAK DOWN THE RIDGE OVER OUR HEADS
TONIGHT.

02/12Z SOUNDING PROFILE SHOWS THE INFLUENCE OF THE UPPER RIDGE
OVERHEAD WITH A SUBSIDENCE INVERSION SIGNATURE AROUND 750MB. ABOVE
THIS LAYER IT ON THE DRY SIDE. THE RESULTING PW IS LOW AROUND
1.7"...WHICH IS BELOW AVERAGE FOR EARLY SEPTEMBER...BUT NOT AN
EXTREME VALUE. WE HAVE SEEN A BIT OF COOLING IN THE MID-LEVELS SINCE
MONDAY...POSSIBLY THE VERY BEGINNING INFLUENCE OF THE APPROACHING
TUTT. WILL EXPECT TO SEE ANOTHER DEGREE OR 2 OF COOLING IN THE
MID-LEVELS OVER THE NEXT 24 TO 36 HOURS AS THE TUTT PASSES JUST TO
OUR SOUTH. THIS COOLING ALONG WITH OUR EVENTUAL POSITION ON THE
EASTERN PERIPHERY OF THE TUTT (FAVORED FOR UPWARD MOTION AND
CONVECTION) MAY LEAD TO ENHANCED CONVECTION LATER IN THE WEEK.

BACK TO TODAY. SOME MIXED SIGNALS REGARDING CONVECTIVE TIMING AND
EVOLUTION FOR THE AFTERNOON AND EVENING. HIRES CONVECTION ALLOWING
MODELS ARE KIND OF SPLIT...WITH A FEW MEMBERS RATHER ACTIVE ALONG
THE I-75 CORRIDOR LATER TODAY...AND A FEW MEMBERS WHO HAVE TROUBLE
GENERATING MUCH CONVECTION...AND ESPECIALLY DEEP CONVECTION. MORE
THAN LIKELY IT IS DIFFERING WAYS THE GUIDANCE IS HANDLING THE
SUBSIDENCE OF THE UPPER RIDGE RESULTING IN THE DIFFERENCES. AM
TENDING TO SIDE ON THE MORE ACTIVE CONVECTION SOLUTIONS. THE
SUBSIDENCE INVERSION IS THERE...BUT IS NOT REALLY PRONOUNCED. GIVEN
THE WEAKNESS OF THE OVERALL SUBSIDENCE AND THE EASTERLY FLOW BEING
FAVORED FOR ENHANCED CONVERGENCE/UPDRAFTS ALONG THE FLORIDA WEST
COAST WILL KEEP HIGH END CHANCE POPS IN THE FORECAST ALONG THE
ENTIRE I-75 CORRIDOR. SIMILAR TO THE PAST FEW DAYS...THE STORMS ARE
LIKELY TO BREAK OUT FIRST DURING THE EARLY/MID AFTERNOON DOWN TOWARD
FORT MYERS AND OVER THE INTERIOR SOUTH (HIGHLANDS/DESOTO/HARDEE
COUNTIES)...AND THEN MIGRATE/EVOLVE NORTH AND WEST INTO THE TAMPA
BAY AREA AND NATURE COAST DURING THE LATE AFTERNOON/EARLY EVENING.

THE EASTERLY FLOW JUST ABOVE THE SURFACE IS 8-10 KNOTS THIS
AFTERNOON WHICH WILL SLOW THE INLAND PROPAGATION OF THE
SEA-BREEZE...BUT NOT STOP IT. THEREFORE...WOULD EXPECT THE BREEZE TO
BE SET UP NEAR OR JUST INSIDE OF I-75 BY LATE AFTERNOON...AND IT
WILL BE THIS ZONE WHERE STORMS WILL IGNITE AS THE EAST COAST
SEA-BREEZE ARRIVES AND INTERACTS.

STORM MOTION WILL BE WESTWARD AFTER INITIATION...SO MARINERS SHOULD
BE AWARE OF THE WEATHER OVER LAND TO THEIR EAST AND BE PREPARED FOR
STORMS TO RAPIDLY DEVELOP AND MOVE OFFSHORE LATER TODAY. THE
ACTIVITY WILL ALL PUSH OFFSHORE WITHIN A COUPLE HOURS OF SUNSET AND
PROVIDE THE REGION WITH A MOSTLY DRY AND SEASONABLE OVERNIGHT
PERIOD.

&&

.AVIATION...
VFR CONDITIONS PREVAIL ACROSS THE REGION LATE THIS MORNING.
BEGINNING TO SEE THE FIRST OF A CU FIELD BEGIN TO DEVELOP. SCT
SHOWERS AND STORMS WILL BE MOVING EAST TO WEST ACROSS THE PENINSULA
DURING THE AFTERNOON. KFMY/KRSW/KPGD WILL BE FIRST TO SEE THE STORMS
IN THE VICINITY BY MID AFTERNOON. FURTHER NORTH AROUND THE TAMPA BAY
TERMINALS STORMS ARE LIKELY TO BE LATER IN THE AFTERNOON AND EVENING
HOURS. AWAY FROM ANY STORMS...VFR CONDITIONS WILL PREVAIL THROUGH
THE TAF PERIOD.

&&

.MARINE...
EAST SOUTHEAST WINDS LESS THAN 15 KNOTS AND SEAS 2 FEET OF LESS
WILL CONTINUE INTO NEXT WEEK AS HIGH PRESSURE OVER THE ATLANTIC
RIDGES WEST OVER THE FLORIDA PENINSULA. THE SEA BREEZE WILL SET UP
ALONG THE COASTLINE EACH DAY TURNING THE WINDS TO AN ONSHORE FLOW
OUT OF THE SOUTHWEST THROUGH NORTHWEST DIRECTION. SCATTERED SHOWERS
AND STORMS WILL BE POSSIBLE EACH DAY DEVELOPING OVER LAND AND THEN
PUSHING WESTWARD OVER THE COASTAL WATERS DURING THE EVENING HOURS.
THE ONLY EXPECTED HAZARD WILL BE GUSTY WINDS AND HIGHER SEAS IN THE
VICINITY OF THUNDERSTORMS.

&&

.PRELIMINARY POINT TEMPS/POPS...
TPA  91  76  91  76 /  50  30  40  30
FMY  93  74  91  74 /  50  10  50  20
GIF  93  74  92  74 /  40  10  40  10
SRQ  92  75  91  73 /  50  30  50  30
BKV  93  72  93  71 /  50  20  40  30
SPG  92  79  90  78 /  50  30  40  30

&&

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

&&

$$

UPDATE/AVIATION...MROCZKA
MARINE...WYNN






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