Area Forecast Discussion
Issued by NWS Tampa Bay Area, FL

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000
FXUS62 KTBW 220825
AFDTBW

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE TAMPA BAY RUSKIN FL
425 AM EDT WED OCT 22 2014

.SHORT TERM (TODAY - THURSDAY)...
CURRENTLY AT THE SURFACE...A WEAK COLD FRONT EXTENDS FROM AN AREA OF
LOW PRESSURE OFF THE MID-ATLANTIC COAST SOUTHWESTWARD INTO NORTHEAST
FLORIDA AND THROUGH THE NATURE COAST AND INTO THE EASTERN GULF OF
MEXICO. WELL TO THE SOUTHWEST OF THE AREA...TROPICAL DEPRESSION 9 IS
LOCATED IN THE BAY OF CAMPECHE...WITH TROUGHING EXTENDING
EAST-NORTHEASTWARD AND INTO THE FLORIDA STRAIGHTS. INFRARED
SATELLITE IMAGERY SHOWS CLEAR SKIES ACROSS FAR NORTHERN ZONES...WITH
MOSTLY CLOUDY OR CLOUDY SKIES ACROSS CENTRAL AND SOUTHERN LOCALES.
MEANWHILE...RADAR IMAGERY SHOWS SOME ISOLATED SHOWERS OFF THE
SOUTHWEST FLORIDA COAST. MAIN SHORT TERM CONCERN FOR TODAY REVOLVES
AROUND POPS.

TODAY...
THE SURFACE COLD FRONT WILL PUSH STEADILY SOUTHWARD THROUGH THE
DAY...REACHING FAR SOUTHERN ZONES BY THIS EVENING. THE DEEPEST LAYER
MOISTURE WILL REMAIN ACROSS FAR SOUTHERN LOCALES THROUGH THE
DAY...WITH COLUMN MOISTURE DECREASING ACROSS NORTHERN AND CENTRAL
AREAS AS THE COLD FRONT SHIFTS SOUTHWARD. THE CONVECTION ALLOWING
MODELS ARE IN GOOD AGREEMENT SHOWING RAIN FREE CONDITIONS THROUGH
THE MORNING HOURS...WITH ISOLATED TO SCATTERED SHOWERS AND
THUNDERSTORMS DEVELOPING ACROSS SOUTHERN AREAS THIS AFTERNOON AS THE
COLD FRONT AND DEEP LAYER MOISTURE GRADIENT SHIFTS INTO THESE AREAS.
THE GLOBAL MODELS SEEM TO BE KEYING IN ON THESE FEATURES AS
WELL...SO WILL SHOW SLIGHT CHANCE/CHANCE POPS GENERALLY ALONG A
ENGLEWOOD TO SEBRING LINE DURING THE AFTERNOON HOURS. MODEL RELATIVE
HUMIDITY TIME/HEIGHT CROSS SECTIONS SHOW QUITE A BIT OF HIGH CLOUD
LINGERING OVER CENTRAL AND SOUTHERN ZONES THROUGH THE MORNING AIDED
BY THE RIGHT REAR QUAD OF A 100+ KNOT UPPER JET. THE BEST JET
FORCING WILL RE-FOCUS ACROSS SOUTH FLORIDA THIS AFTERNOON...SO
EXPECT DECREASING CLOUDINESS ACROSS CENTRAL ZONES THROUGH THE
DAY...WITH MOSTLY SUNNY SKIES ACROSS FAR NORTHERN ZONES...AND MOSTLY
CLOUDY SKIES ACROSS SOUTHERN ZONES. HIGH TEMPERATURES ARE EXPECTED
TO TOP OUT IN THE LOWER 80S ACROSS THE FAR NORTH AND THE MID TO
UPPER 80S ACROSS CENTRAL AND SOUTHERN ZONES.

TONIGHT...
THE COLD FRONT WILL WASH OUT ACROSS SOUTH FLORIDA WITH HIGH
PRESSURE THEN BUILDING NORTH OF THE REGION. THIS SHOULD KEEP THE
DEEPEST LAYER MOISTURE ACROSS SOUTH FLORIDA AND THE FLORIDA
STRAIGHTS THROUGH THE NIGHT. WILL KEEP SOME SLIGHT CHANCE POPS
GOING IN THE EVENING ACROSS HIGHLANDS COUNTY TO ACCOUNT FOR ANY
LINGERING CONVECTION...WITH RAIN FREE CONDITIONS THEN EXPECTED
OVERNIGHT. EXPECT MOSTLY CLEAR TO PARTLY CLOUDY SKIES ACROSS
NORTHERN AND CENTRAL ZONES...WITH MOSTLY CLOUDY CONDITIONS LIKELY
CONTINUING ACROSS FAR SOUTHERN LOCALES. OVERNIGHT LOWS ARE
EXPECTED TO BOTTOM OUT IN THE UPPER 40S TO LOWER 50S ACROSS THE
NATURE COAST...AND AROUND 60 TO AROUND 70 ACROSS CENTRAL AND
SOUTHERN LOCALES.

THURSDAY...
THE SURFACE TROUGH OF LOW PRESSURE WILL REMAIN SUPPRESSED ACROSS FAR
SOUTH FLORIDA AND THE FLORIDA KEYS THROUGH THE DAY...SO EXPECT RAIN
FREE CONDITIONS ACROSS THE FORECAST AREA. THE BEST JET FORCING WILL
WEAKEN CONSIDERABLY OVER THE LOCAL AREA AS THE MAIN UPPER JET
REFOCUSES ACROSS THE LOWER MISSISSIPPI VALLEY AND NORTH-CENTRAL GULF
OF MEXICO IN ADVANCE OF AN APPROACHING UPPER LEVEL TROUGH. AS A
RESULT...EXPECT DECREASING CLOUDINESS ACROSS SOUTHERN AREAS...WITH
GENERALLY MOSTLY SUNNY TO PARTLY CLOUDY SKIES PREVAILING BY THE
AFTERNOON. HIGH TEMPERATURES ARE EXPECTED TO TOP OUT AROUND 80
NORTH...TO THE LOWER AND MIDDLE 80S ACROSS CENTRAL AND SOUTHERN
ZONES.

&&

.LONG TERM (THURSDAY NIGHT-WEDNESDAY)...
A VIGOROUS S/WV WILL MOVE SE OUT OF GA AND ACROSS FL FRI NIGHT.
MODELS SHOW SIGNIFICANT H7-H3 Q-VECTOR CONVERGENCE WHICH INDICATES
LARGE SCALE LIFT FRI AND FRI NIGHT W/ THIS SYSTEM. THAT
SAID...AVAILABLE MOISTURE WILL STRONGLY LIMIT PRECIP POTENTIAL AS
DEEPEST MOISTURE REMAINS CONFINED ACROSS S FL ALONG AND SOUTH OF A
STATIONARY FRONTAL BOUNDARY FORECAST TO BE NEAR OR JUST SOUTH OF
LAKE OKEECHOBEE PER GFS AND ECMWF. SHOULD NOTE THE NAM IS MUCH
MORE AGGRESSIVE DRAWING THIS BOUNDARY AND ASSOC MOISTURE NORTH
AHEAD OF THE UPR S/WV ON FRI...BUT THIS IS DUE TO A MUCH FURTHER
NORTH FORECAST POSITION OF TD9 IN THE NAM WHICH HELPS PUSH
MOISTURE NORTH INTO CEN FL DUE TO LOW LEVEL ESE FLOW AROUND THE
LOW LEVEL CENTER. AM COMPLETELY DISREGARDING THIS SOLN GIVEN
EXPECTED TRACK OF THE SYSTEM MUCH FURTHER SOUTH PER ECMWF...GFS
AND NHC OFFICIAL TRACK FORECAST. GIVEN THIS...APPEARS ONLY FAR SRN
COUNTIES WILL HAVE ENOUGH MOISTURE TO PROVIDE SIG PRECIP
POTENTIAL ASSOC W/ THE S/WV WILL SHOW 20-35 POPS WHICH IS MOST
CLOSELY FOLLOWING MAV GUIDANCE. DEEP S FL COULD GET SIGNIFICANT
RAINFALL GIVEN DEEP TROPICAL AIRMASS OVER THAT REGION...BUT THE
HIGHEST QPF IS EXPECTED TO REMAIN JUST SOUTH OF FMY AREA.
REINFORCING HIGH PRESSURE WILL SHOVE THE FRONT AND AFOREMENTIONED
MOISTURE POOL WELL SE OF THE REGION BY SAT WITH COOLER AND DRIER
AIR FILTERING INTO THE AREA. THIS WILL PROVIDE SOME CRISP...COOL
MORNING LOWS SLIGHTLY BELOW NORMAL OVER THE WEEKEND WITH HIGHS
GENERALLY NEAR NORMAL VALUES WHICH IS IN THE LOW TO MID 80S.
EXPECT A WARMING AND MOISTENING TREND EARLY NEXT WEEK AS MID TO UP
LEVEL RIDGE MOVES ACROSS THE AREA AND ESE FLOW RETURNS AS SFC HIGH
MOVES OFF THE MID ATL COAST.

VERY UNCLEAR WRT WHAT HAPPENS TO TD9 NEXT WEEK. THE GFS SPLITS
ENERGY ASSOC W/ TD9 IN TWO PIECES ON EITHER SIDE OF CUBA. ONE
PIECE RACES OFF TO THE ENE AHEAD OF THE AFOREMENTIONED S/WV WITH
THE OTHER REMAINING IN THE WRN CARIBBEAN. GFS THEN STRENGTHENS
THE PIECE LEFT BEHIND AND MOVES IT NORTH INTO THE ERN GOMEX AS A
STRONG TS. COULD HAPPEN...BUT WAY TO COMPLICATED AND NOT NEAR
ENOUGH SUPPORT BY OTHER MODELS TO PUT MUCH STOCK IN THAT SOLN OUT
7 DAYS. THAT SAID...SHOULD NOTE THE ECMWF DOES SHOWS A WEAK LOW
PRESSURE FEATURE BETWEEN YUCATAN AND CUBA AS WELL...SO WILL BE
INTERESTING TO SEE WHAT BECOMES OF TD9 NEXT WEEK. FOR NOW FOLLOWED
ECMWF FOR LAST FEW PERIODS OF THE FORECAST WHICH IS MUCH LESS
AGGRESSIVE THAN THE GFS.

&&

.AVIATION...
GENERALLY VFR CONDITIONS ARE EXPECTED THROUGH THE TAF FORECAST
PERIOD. COULD SEE SOME ISOLATED TO SCATTERED SHRA/TSRA AT
KFMY...KPGD AND KRSW THIS AFTERNOON...AND HAVE INDICATED VCTS
BETWEEN 18Z AND 21Z.

&&

.MARINE...
HIGH PRESSURE WILL BUILD NORTH OF THE REGION THROUGH THE WEEKEND
WITH A TROUGH OF LOW PRESSURE REMAINING SUPPRESSED ACROSS THE
FLORIDA STRAIGHTS. EXPECT EXERCISE CAUTION OR ADVISORY LEVEL WINDS
TO DEVELOP ACROSS ALL WATERS TONIGHT AND LINGER THROUGH THURSDAY
MORNING. ELEVATED EAST-NORTHEAST FLOW WILL THEN CONTINUE ACROSS THE
WATERS THROUGH THE WEEKEND...WITH WINDS PERIODICALLY REACHING
EXERCISE CAUTION OR ADVISORY LEVELS.

&&

.FIRE WEATHER...
A WEAK COLD FRONT WILL SLIDE SOUTHWARD THROUGH THE REGION
TODAY...WITH HIGH PRESSURE THEN BUILDING NORTH OF THE AREA THROUGH
THE WEEKEND. RAIN CHANCES WILL BE CONFINED TO LOCATIONS GENERALLY
SOUTH OF THE TAMPA BAY AREA THROUGH THE FORECAST PERIOD...WITH ALL
AREAS EXPECTED TO SEE RAIN FREE CONDITIONS BY THE WEEKEND. THE
PRESSURE GRADIENT WILL TIGHTEN BETWEEN HIGH PRESSURE TO THE NORTH
AND TROUGHING ACROSS THE FLORIDA STRAIGHTS BEGINNING TONIGHT...WITH
MODERATE EAST-NORTHEAST WINDS CONTINUING THROUGH THE WEEKEND.
RELATIVE HUMIDITY VALUES MAY DROP TO AROUND 35 PERCENT ACROSS THE
NATURE COAST THIS AFTERNOON AND THURSDAY AFTERNOON...WITH
HUMIDITY VALUES THEN REMAINING ABOVE CRITICAL LEVELS FRIDAY
AND THROUGH THE WEEKEND.

FOG POTENTIAL TONIGHT...FOG IS NOT EXPECTED.

&&

.PRELIMINARY POINT TEMPS/POPS...
TPA  85  63  83  63 /   0   0   0   0
FMY  85  68  85  70 /  30  10  10  20
GIF  84  61  81  61 /  10   0   0  10
SRQ  86  65  84  65 /  10  10   0  10
BKV  85  53  82  53 /   0   0   0  10
SPG  84  68  83  68 /   0   0   0  10

&&

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

&&

$$

SHORT TERM/AVIATION/MARINE/FIRE WEATHER...JELSEMA
LONG TERM/DECISION SUPPORT...GITTINGER





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