AFDTAE

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE TALLAHASSEE FL
945 AM EDT FRI JUL 29 2011

.DISCUSSION...12 UTC SURFACE ANALYSIS SHOWS A 1020 MB SURFACE
CENTERED ACROSS SOUTHEAST ALABAMA WITH ANOTHER HIGH ACROSS THE FAR
WESTERN ATLANTIC...JUST SOUTHEAST OF WILMINGTON NC. TROPICAL STORM
DON WAS LOCATED ACROSS THE SOUTHWESTERN GULF OF MEXICO MOVING TOWARD
SOUTHERN TEXAS. THE NEAR SURFACE AIRMASS WAS STILL PLENTY HUMID WITH
DEWPOINTS IN THE LOW TO MID 70S ACROSS THE REGION.

THE 12 UTC 500 MB ANALYSIS AND VAPOR IMAGERY SHOW THE LARGE 596 DM
RIDGE THAT WAS ACROSS THE APPALACHIANS HAD MOVED TO A POSITION JUST
OFF THE SOUTH CAROLINA COAST. VAPOR IMAGERY SHOWS THAT THIS RIDGE
CONTINUES TO BUILD SOUTHWARD TOWARD THE FLORIDA PENINSULA AND SHOULD
BE MOVING OVERHEAD BY SATURDAY.

THE 12 UTC KTAE SOUNDING SHOWS A DRIER AIRMASS THAN YESTERDAY WITH
THE PRECIPITABLE WATER DOWN TO 1.82 INCHES. IT WAS EVEN DRIER DOWN
AT TAMPA...WITH A PW OF 1.56 INCHES. THE MID LEVELS OF THE SOUNDING
FROM AROUND 850 TO 500 MB HAVE WARMED BETWEEN 2C AND 4C OVER THE
LAST 24 ACROSS THE REGION...SHOWING THE BUILDING INFLUENCE OF THE
RIDGE. AS A RESULT...A MODIFIED SURFACE PARCEL OF 96/69 YIELDS ONLY
AROUND 1700 J/KG SBCAPE WITH A LIFTED INDEX AROUND -4. THESE ARE
MEAGER VALUES FOR LATE SUMMER...INDICATIVE OF ONLY ISOLATED
THUNDERSTORM COVERAGE AT BEST.

INITIALLY...THE 1000-700 MB FLOW IS OUT OF THE SOUTHEAST AT 5 TO 10
KNOTS...BUT ALL THE GUIDANCE SHOWS THIS FLOW WEAKENING AND BECOMING
MORE VARIABLE AS HIGH PRESSURE ALOFT BUILDS OVER THE REGION. AS A
RESULT...THE SEA BREEZE SHOULD HAVE DIFFICULTY MOVING INLAND TODAY.
THE BEST AREAS FOR ENHANCED CONVERGENCE WILL BE IN THE FLA BIG BEND
AND ALONG THE SOUTHERN PORTIONS OF THE APALACHEE RIVER WHERE THE
PANHANDLE AND WESTERN BIG BEND SEA BREEZES USUALLY COLLIDE. GIVEN
THE LACK OF SIGNIFICANT DEVELOPMENT SEEN IN THE MODELS...WILL ADJUST
POPS DOWNWARD ABOUT 10 PERCENT FROM WHAT WAS INHERITED. TEMPERATURES
THROUGH 13Z WERE RUNNING A LITTLE BIT ABOVE FORECAST. WILL SEE IF
THIS TREND CONTINUES WITH THE 14Z OBS...BUT SUSPECT A SLIGHT UPWARD
ADJUSTMENT WILL BE NEED TO THE TEMPERATURES ACROSS SOUTHERN GEORGIA
AND INTO PORTIONS OF NORTH FLORIDA TO INDICATE A FEW SPOTS IN THE
UPPER 90S. HEAT INDICIES WILL LIKELY EXCEED 105 DEGREES TODAY...BUT
REMAIN JUST BELOW OUR ADVISORY CRITERIA OF 110. WILL HAVE THE
UPDATES OUT SOON. HAVE A GREAT DAY!

&&

.AVIATION...A SLIGHTLY DRIER AND MORE STABLE AIRMASS WILL BE IN
PLACE ACROSS THE REGION TODAY...LIMITED THE CHANCES FOR TSRA AT AREA
TERMINALS. VFR CONDITIONS ARE EXPECTED TO DOMINATE THROUGH THE DAY
TODAY WITH TEMPOS TO MVFR CONDITIONS OVERNIGHT.

&&

.MARINE...WINDS CONTINUE TO DIMINISH ACROSS THE COASTAL WATERS. SOME
WEAK LINGERING SWELL FROM DON IS KEEPING SEAS IN THE 3 TO 4 FEET
RANGE OVER THE OFFSHORE WATERS. THIS SWELL WILL GRADUALLY LESSEN
LATER TODAY WITH SEAS RETURNING TO TYPICAL SUMMER TIME LOW LEVELS BY
SATURDAY.

&&

.TAE WATCHES/WARNINGS/ADVISORIES...
AL...NONE.
GA...NONE.
FL...NONE.
GM...NONE.

&&

$$