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Area Forecast Discussion

000
FXUS62 KTAE 241326
AFDTAE

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE TALLAHASSEE FL
926 AM EDT FRI OCT 24 2008

.DISCUSSION...11 UTC SURFACE ANALYSIS PLACES THE 1010 MB SURFACE LOW
ABOUT 85 MILES SOUTH OF PENSACOLA FLORIDA OVER THE GULF MEXICO. A
WARM FRONT EXTENDED EAST NORTHEASTWARD FROM THIS LOW ACROSS THE FAR
NORTHEASTERN GULF OF MEXICO TO NEAR CEDAR KEY AND ACROSS NORTH
CENTRAL FLORIDA. A COLD FRONT WAS ANALYZED ACROSS THE CENTRAL GULF.
A BOUNDARY ALSO EXISTS ACROSS THE SOUTHEAST FROM THE SURFACE LOW
NORTHWARD INTO THE OHIO VALLEY THAT SEPARATES THE DRY COLD AIR OVER
THE SOUTHERN MISSISSIPPI VALLEY AND THE COOLER MOIST AIR MOVING IN
FROM THE NORTHEAST ACROSS THE SOUTHERN ATLANTIC STATES.
ESSENTIALLY...THREE AIRMASS TYPES ARE MEETING NEAR THE SURFACE
LOW...WITH A TRUE TROPICAL TYPE AIRMASS SOUTH OF OUR WARM FRONT. THE
LARGE HIGH PRESSURE RIDGE WAS CENTERED NEAR NYC THIS MORNING WITH
ANOTHER AREA OF HIGH PRESSURE NEAR AUSTIN TX.

UPPER AIR FEATURES THIS MORNING HAVE CHANGED A LITTLE FROM 12 HOURS
AGO. THE HIGH AMPLITUDE RIDGE HAS SHIFTED EASTWARD AND IS NOW OVER
THE NORTHEAST. THIS CUT OFF LOW IS NOW A CLOSED LOW WITH A BIT OF A
NEGATIVE TILT AND STARTING TO MOVE NORTHEAST INTO THE UPPER
MISSISSIPPI RIVER VALLEY. THIS WILL HELP PUSH THE STORM SYSTEM
ACROSS THE CENTRAL GULF EASTWARD AND THROUGH OUR REGION LATER THIS
AFTERNOON.

THE 12 UTC MORNING SOUNDING AT KTAE IS QUITE REMARKABLE. TOTALLY
SATURATED AIRMASS UP TO 625 MB. THIS ISN`T ALL THAT SURPRISING GIVEN
THE ONGOING RAIN AROUND THE AREA AND SIGNIFICANT ISENTROPIC ASCENT
ONGOING THROUGH THE LOW AND MID LEVELS OF THE ATMOSPHERE. WHAT IS
REMARKABLE IS THE WIND PROFILE. WHILE WINDS AT THE SURFACE WERE
AROUND 5 KNOTS...JUST 300 METERS AGL THE WINDS ARE 25 KNOTS WHILE AT
750 METERS AGL THE WINDS ARE 45 KNOTS WITH A 55 KNOT READING AT 1.5
KILOMETERS AGL. WIND DIRECTION IS SHIFTING FROM 090 AT THE SURFACE
TO 220 AT 6 KILOMETERS AND ACCELERATING THROUGH THIS LAYER. THIS IS
RATHER IMPRESSIVE SHEAR...BUT WITH INSTABILITY LACKING
DESTABILIZATION WILL BE NEEDED TO TAP THE OVERLY FAVORABLE KINEMATIC
FIELD.

ISENTROPIC ASCENT ONGOING THIS MORNING ACROSS THE FLORIDA PANHANDLE
AND SOUTHERN GEORGIA. THE AREA OF PRECIPITATION FILLING IN NOW
ACROSS THE FLORIDA PANHANDLE AND WESTERN BIG BEND SHOULD BE SHIFTING
NORTHWARD INTO GEORGIA THROUGHOUT THE MORNING HOURS. WHILE WE
HAVEN`T SEEN MUCH DEVELOPMENT IN THE WARM SECTOR THIS
MORNING...THERE IS THE POTENTIAL FOR SOME LATER THIS AFTERNOON.
GIVEN THE IMPRESSIVE SHEAR PROFILES...THE POTENTIAL FOR SOME
ISOLATED SEVERE STORMS CANNOT BE DISCOUNTED...WITH ISOLATED
TORNADOES BEING THE MAIN THREAT. THIS THREAT WILL BE GREATEST ACROSS
THE SOUTHEAST FLORIDA BIG BEND AND THE COASTAL WATERS WHERE THE
COMBINATION OF INSTABILITY AND SHEAR WILL BE GREATEST. NORTH OF THE
FLORIDA BORDER...IT APPEARS AS THOUGH ANY THUNDER THAT OCCURS WILL
BE FROM ELEVATED STORMS.

CURRENT FORECAST IS LARGELY ON TRACK THIS MORNING. THE BACK EDGE OF
THE PRECIPITATION IS NOW GETTING INTO OUR FAR WESTERN ZONES AND
SHOULD BE CLEARING SOUTHEAST ALABAMA AND PORTIONS OF THE FLORIDA
PANHANDLE BY MIDDAY. WILL MAKE SOME MINOR ADJUSTMENTS TO OUR POPS TO
FAVOR HIGHER CHANCES STILL IN SOUTH CENTRAL GEORGIA AND THE FLORIDA
BIG BEND AFTER 2 PM...BUT OVERALL LOOKS LIKE EVERYTHING IS ON TRACK.

&&

.AVIATION...MVFR TO OCNL IFR CIGS/VSBYS WILL CONTINUE THROUGH THE
DAY. AN ISOLATED TSRA WILL BE POSSIBLE FOR THE FL TERMINALS...AT PFN
THIS MORNING AND TLH THIS AFTERNOON. GUSTY ELY WINDS WILL SWING
AROUND TO THE N OR NW AFTER THE COLD FRONTAL PASSAGE THIS EVENING.
AN EXTENSIVE AREA OF IFR CIGS WILL PREVAIL DURING THE OVERNIGHT
HOURS WITH OCNL MVFR VSBYS. THE GA TERMINALS (ABY AND VLD) COULD SEE
CIGS/VSBYS DROP INTO THE LIFR OR VLIFR RANGE BEFORE DAWN SAT.

&&

.MARINE...WITH THE APPROACH OF THE SURFACE LOW THE WINDS HAVE
DECREASED OVER THE COASTAL WATERS WEST OF APALACHICOLA TO AROUND 20
KNOTS...THUS WE HAVE LET THE GALE WARNING EXPIRE THERE. WE HAVE SEEN
NEAR CONTINUOUS GUSTS TO GALE FORCE THIS MORNING OVER OUR MIDDLE
MARINE ZONE...SO EXTENDED THE GALE WARNING UNTIL 15Z. WHILE
OBSERVATION FROM C TOWER IS NOT AT THE STANDARD 10 METERS...BUT AT
35 METERS...WE HAVE SEEN SUSTAINED WINDS AT THIS HEIGHT OF 38 KNOTS
WITH GUSTS AS HIGH AS 43 KNOTS. COLD FRONT WILL MOVE THROUGH THE
WATERS TONIGHT SHIFTING ALL WINDS TO NORTHWEST. WE MAY SEE A PERIOD
OF CAUTIONARY CONDITIONS TONIGHT...WITH WINDS GRADUALLY SUBSIDING
INTO SUNDAY.

&&

.FIRE WEATHER...AMPLE MOISTURE WILL PRECLUDE RED FLAGS TODAY. THE
AIR MASS WILL BECOME MUCH DRIER THIS WEEKEND. CURRENT FORECAST GRIDS
SUPPORT RED FLAG CONDITIONS IN SE AL AND MARGINAL CONDITIONS IN OUR
INLAND FL ZONES W OF TLH. A WATCH WILL LIKELY BE POSTED FOR SAT WITH
THIS AFTERNOON`S PACKAGE. RED FLAG CONDITIONS WILL BE POSSIBLE FOR
ALL OF OUR FL ZONES FROM SUN-TUE AND POSSIBLY BEYOND.

&&

.TAE WATCHES/WARNINGS/ADVISORIES...
AL...NONE.
GA...NONE.
FL...HIGH SURF ADVISORY UNTIL 4 PM EDT /3 PM CDT/ THIS AFTERNOON FOR
     THE FOLLOWING ZONES: BAY...COASTAL WALTON...FRANKLIN...GULF.

GM...SMALL CRAFT ADVISORY UNTIL 8 PM EDT THIS EVENING FOR THE
     FOLLOWING ZONES: DESTIN TO WEST OF APALACHICOLA OUT TO 60
     NAUTICAL MILES. EAST OF THE OCHLOCKONEE RIVER ENTRANCE TO THE
     SUWANNEE RIVER OUT TO 20 NAUTICAL MILES.

     GALE WARNING UNTIL 11 AM EDT THIS MORNING FOR THE FOLLOWING
     ZONES FOLLOWED BY A SMALL CRAFT ADVISORY UNTIL 8 PM EDT THIS
     EVENING: APALACHICOLA TO THE OCHLOCKONEE RIVER ENTRANCE OUT TO
     60 NAUTICAL MILES.

&&

$$

AVIATION/FIRE WEATHER...WOOL
REST OF DISCUSSION...GODSEY