Area Forecast Discussion
Issued by NWS Tampa Bay Area, FL

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000
FXUS62 KTBW 211849
AFDTBW

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE TAMPA BAY RUSKIN FL
249 PM EDT TUE OCT 21 2014

.SYNOPSIS...
ALOFT - A LOW OFFSHORE BRITISH COLUMBIA TROUGHED DOWN ACROSS THE
WESTERN STATES...A RIDGE REACHED ACROSS THE MID CONUS FROM THE
RIO GRANDE RIVER TO WESTERN HUDSON BAY...AND A TROUGH EXTENDED
FROM EASTERN QUEBEC TO THE EASTERN GULF COAST AND CONTAINED A
CLOSED LOW OVER THE LOWER GREAT LAKES. SURFACE - HIGH PRESSURE
WAS ALONG THE ONTARIO/QUEBEC BORDER...A LOW OVER THE MID-ATLANTIC
COAST TRAILED A COLD FRONT THAT ARCED THROUGH THE MID-MISSISSIPPI
VALLEY TO THE NORTHERN HIGH PLAINS...HIGH PRESSURE SPRAWLED ACROSS
THE SOUTHERN PLAINS AND MUCH OF THE GULF COAST...A WEAK TROUGH WAS
ACROSS OVER FL...ATLANTIC HIGH PRESSURE RIDGED TO THE BAHAMAS...
AND AREA OF LOW PRESSURE WAS IN THE SOUTHERN BAY OF CAMPECHE.

&&

.SHORT TERM (TONIGHT AND WEDNESDAY)...
THE UPPER RIDGE TO THE WEST SLIDES EASTWARD TONIGHT WITH THE
UPPER TROUGH AXIS CLEARING THE STATE AND MOVING OUT OVER THE
ATLANTIC...WITH THE SURFACE TROUGH AND ASSOCIATED DEEPER MOISTURE
SAGGING BACK DOWN ACROSS SOUTHERN FL.

DURING WED...THE UPPER RIDGE REACHES THE MISSISSIPPI VALLEY WHILE
THE UPPER TROUGH DEEPENS INTO A MORE ROBUST CLOSED LOW OVER
ATLANTIC COASTAL WATERS. THE ONTARIO/QUEBEC HIGH PRESSURE BUILDS
DOWN ACROSS THE GREAT LAKES AND REINFORCES THE SOUTHERN
PLAINS/GULF COAST HIGH PRESSURE. IN RESPONSE THE COLD FRONT TRACKS
DOWN INTO CENTRAL FL AS THE SURFACE TROUGH AND THE DEEPEST
MOISTURE SETTLES IN BETWEEN THE KEYS AND CUBA. THE BAY OF CAMPECHE
LOW DRIFTS ON TO THE YUCATAN PENINSULA.

THE CURRENT FORECAST PHILOSOPHY IS TO KEEP SLIGHT CHANCE TO LIKELY
POPS IN THIS AFTERNOON...WITH THE POPS TRENDING DOWN FROM
MANATEE-POLK SOUTHWARD. THEN AS THE TROUGH SINKS IN ACROSS SOUTH
FL RAIN CHANCES DECREASE AND EXIT THE SOUTHERN COUNTIES IN THE
EVENING. HIGH PRESSURE TO THE NORTH GETS REINFORCED TONIGHT THEN
SETTLES ACROSS THE STATE... PUSHING THE COLD AND DRY FRONT INTO
CENTRAL FL...WITH SOME DRIER AND SLIGHTLY COOLER AIR (WITH AN
EMPHASIS ON SLIGHT) IN ACROSS MUCH OF THE AREA. HOWEVER LINGERING
DEEPER MOISTURE...FROM THE SURFACE TROUGH TO THE SOUTH...WILL
SUPPORT SOME LOW POPS IN THE SOUTHERN MOST COUNTIES. LOWS TONIGHT
WILL RANGE FROM JUST UNDER NORMAL IN THE NORTH TO JUST ABOVE IN
THE SOUTH. HIGHS WED WILL WARM TO ABOVE NORMAL...BY 2 TO 4
DEGREES...THANKS TO SOME CLEARING SKIES.

.LONG TERM (WEDNESDAY NIGHT-TUESDAY)...WE CONTINUE TO WATCH THE AREA
OF DISTURBED WEATHER ACROSS BAY OF CAMPECHE THAT NHC NOW SHOWS A 50%
CHANCE OF TROPICAL DEVELOPMENT OVER THE NEXT 5 DAYS AS IT MOVES EAST
TOWARD CUBA. THAT SAID MODELS HAVE TRENDED TOWARDS A DRY FORECAST
FOR THE EXTENDED AS ONE UPR LOW ACROSS THE ERN US LIFTS NE BUT IS
QUICKLY REPLACED BY ANOTHER TROUGH BY THE WEEKEND...ALTHOUGH THIS
TROUGH WILL BE A BIT MORE PROGRESSIVE AS IT PUSHES EAST INTO THE WRN
N ATL. THIS MEANS COOL AND DRY HIGH PRESSURE AT THE SFC WILL BE
REINFORCED BY SAT AND THIS HELPS KEEP HIGH MOISTURE CONFINED TO DEEP
S FL AND ALSO HELPS STEER ANY POTENTIAL ORGANIZED TROPICAL SYSTEM
WELL SOUTH OF THE REGION AS IT TRACKS DUE EAST. BASED ON THIS WILL
CONTINUE TO CONFINE MENTION OF SOME VERY LOW POPS ACROSS THE FAR
SOUTH NEAR THE STRONG MOISTURE GRADIENT ON FRI. VERY DRY AIRMASS
WILL PROMOTE LARGE DIURNAL TEMP RANGES WITH LOWS MOSTLY IN THE 50S
AND 60S AND HIGHS GENERALLY IN THE LOW TO MID 80S. ONLY DOWNSIDE
TO THE FORECAST MAY BE THE WINDS WHICH WILL REMAIN ELEVATED FROM
THE NNE THROUGH THE WEEKEND WITH CAUTION LEVEL AT TIMES ACROSS
MARINE AREAS (ESP OFFSHORE ZONES). TEMPS WILL CLIMB LATE IN THE
PERIOD AS UPR RIDGING SLIDES EAST FROM TEXAS TOWARD THE SE US.

&&

.AVIATION...
21/18Z-22/18Z. PREVAILING BKN MID-HIGH CLOUDS BUT WITH THE POTENTIAL
FOR SOME LOWER CIGS/VSBYS KPGD/KRSW/KFMY THROUGH THE EVENING. DRY
AIR WORKS IN OVERNIGHT WITH CLEARING SKIES ALTHOUGH FMY/RSW CONTINUE
BKN VFR...WITH VCSH AFT 22/14Z. LIGHT WINDS...WESTERLY BECOMING
VARIABLE OVERNIGHT...THEN NE WED.

&&

.MARINE...
LOW PRESSURE OVER THE SOUTHWEST GULF OF MEXICO WILL MOVE EAST ACROSS
THE YUCATAN PENINSULA AND CREATE AN EASTERLY FLOW ACROSS FLORIDA.
THE LOW IS FORECAST TO MOVE SOUTH OF FLORIDA LATE FRIDAY AND THEN
OVER THE ATLANTIC OCEAN LEADING TO A NORTHERLY WIND FLOW. A
STRENGTHENING PRESSURE GRADIENT ACROSS FL MAY RESULT IN PERIODS
OF EXERCISE CAUTION AND POSSIBLY ADVISORY LEVEL WINDS WEDNESDAY
NIGHT THROUGH SATURDAY.

&&

.FIRE WEATHER...
HIGH PRESSURE BUILDS IN ACROSS MUCH OF THE AREA BY WEDNESDAY AS A
TROUGH OF LOW PRESSURE...ALONG WITH SOME DEEPER MOISTURE...CONTINUES
ACROSS AND SOUTH OF SOUTHERN FLORIDA. THE HIGH PRESSURE DOMINATES
THE NORTHERN PORTIONS OF THE AREA INTO THE WEEKEND AS THE TROUGH
LINGERS BETWEEN THE KEYS AND CUBA...WITH ENOUGH RESIDUAL MOISTURE
FOR ISOLATED TO SCATTERED SHOWERS AND A FEW STORMS FOR SOUTHERN
LOCATIONS. AN AREA OF LOW PRESSURE WILL MOVE OUT OF THE BAY OF
CAMPECHE...ACROSS THE YUCATAN...AND ALONG THE TROUGH THROUGH THE
WEEK. THIS SYSTEM IS EXPECTED TO REMAIN SOUTH OF FLORIDA BUT MAY
PROVIDE ROBUST WINDS AT TIMES.

RELATIVE HUMIDITY VALUES MAY APPROACH 35 PERCENT ACROSS PORTIONS OF
THE NATURE COAST WEDNESDAY AFTERNOON...OTHERWISE HUMIDITY LEVELS
SHOULD REMAIN ABOVE CRITICAL THRESHOLDS THROUGH THE FORECAST
PERIOD.

FOG POTENTIAL TONIGHT...SOME PATCHY GROUND FOG MAY BE POSSIBLE LATER
TONIGHT...HOWEVER NO SIGNIFICANT OR WIDESPREAD FOG IS EXPECTED.

&&

&&

.PRELIMINARY POINT TEMPS/POPS...
TPA  69  86  64  85 /   0   0   0   0
FMY  70  86  68  87 /  30  30  10  10
GIF  67  85  62  83 /  10   0   0   0
SRQ  68  86  65  86 /  10  10   0   0
BKV  56  86  53  83 /   0   0   0   0
SPG  72  85  69  83 /   0   0   0   0

&&

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

$$

SYNOPSIS/SHORT TERM/AVIATION/FIRE WEATHER...09/RUDE
LONG TERM...88/GITTINGER
MARINE...007/DOUGHERTY
DECISION SUPPORT...24/HUBBARD










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