Flash Flood Warning 6, NWS Tallahassee, FL

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE TALLAHASSEE FL
250 AM EDT WED AUG 25 2010

.SYNOPSIS...03 UTC SURFACE ANALYSIS SHOWS THE WAVY QUASI-STATIONARY
FRONTAL BOUNDARY ACROSS THE FORECAST AREA...GENERALLY FROM NEAR
DESTIN NORTHEAST TO BLAKELY TO NEAR AUGUSTA. A WEAK 1010 MB LOW WAS
ANALYZED ACROSS LAKE EUFAULA. A STRONGER COLD FRONTAL BOUNDARY WAS
LOCATED ACROSS THE MID MISSISSIPPI RIVER VALLEY GIVING THE PLAINS A
BREAK FROM THE HEAT. LOCALLY...IT STILL REMAINS VERY MUGGY WITH
DEWPOINTS IN NORTH FLORIDA STILL IN THE MID AND UPPER 70S. JUST
ACROSS THE FRONTAL BOUNDARY IN EAST CENTRAL ALABAMA...DEWPOINTS ARE
IN THE MID 60S.

THE 500 MB PATTERN AT 00 UTC WAS QUITE INTERESTING WITH A WEAK
BLOCKING TYPE PATTERN OFF THE EASTERN CONUS. THIS BLOCKING SHOULD BE
SHORT-LIVED AS THE TROF TRAVERSING THROUGH THE UPPER MISSISSIPPI
VALLEY WILL BE NEARING NEW ENGLAND IN THE NEXT COUPLE OF DAYS. OUT
WEST...RIDGING WAS BUILDING NEAR LAS VEGAS.

AS A SIDE NOTE...THE LONG PERIOD (28 STRAIGHT LAUNCHES) OF
PRECIPITABLE WATER VALUES ABOVE 2 INCHES HAS COME TO AN END WITH THE
00Z WEDNESDAY SOUNDING...WITH A VALUE DOWN TO 1.72 INCHES.
SIGNIFICANT DRYING HAS OCCURRED OVER THE LAST 24 HOURS ABOVE 600 MB.

&&

.SHORT TERM...TODAY THROUGH FRIDAY.
MODELS ARE ALL IN FAIRLY GOOD AGREEMENT THIS MORNING WITH REGARD TO
THE SHORT TERM FORECAST. UNFORTUNATELY...IT DOESN'T LOOK LIKE THE
FRONTAL BOUNDARY IS GOING TO MAKE MUCH MORE OF A PUSH THROUGH THE
REGION TO CLEAR US OUT. AS A RESULT...THE SHORT TERM PERIOD WILL BE
AN INCREASINGLY UNSETTLED ONE AS TROPICAL MOISTURE OVERRIDES THE
FRONTAL BOUNDARY AND PRODUCES GOOD COVERAGE OF SHOWERS AND STORMS BY
FRIDAY. FOR GRID POPULATION...USED A BLEND OF THE PREVIOUS FORECAST
AND THE 24/12Z EURO AND THE 25/00Z GFS.

INITIALLY...THE STRONG SURGE OF MID LEVEL DRY AIR INDICATED ON VAPOR
IMAGERY THIS MORNING WILL SERVE TO LIMIT MUCH OF THE SHOWER AND
THUNDERSTORM POTENTIAL ACROSS THE NORTHWESTERN HALF OF THE REGION ON
WEDNESDAY. MODEL PRECIPITABLE WATER VALUES IN PARTS OF SOUTHEAST
ALABAMA DROP TO NEAR 1 INCH ON WEDNESDAY AFTERNOON. WHILE THE
MAGNITUDE MIGHT BE A LITTLE EXTREME...THE DOWNWARD TREND IN THE
GUIDANCE MATCHES WELL WITH THE PROGRESSION OF THE MID LEVEL AIR SEEN
ON VAPOR IMAGERY. THUS...SEE NO REASON WHY WE CAN'T KEEP THE
NORTHWESTERN CWA DRY TODAY.

BY THURSDAY...THE FRONTAL BOUNDARY AND DEEP LAYER MOISTURE WILL
BEGIN TO SLOWLY LIFT BACK NORTHWARD. AS THE FRONTAL BOUNDARY
PROVIDES A FOCUS FOR AFTERNOON CONVECTION...THE INCREASING DEEP
LAYER MOISTURE WILL LEAD TO BETTER AFTERNOON SHOWER AND THUNDERSTORM
COVERAGE...ESPECIALLY ACROSS NORTH FLORIDA AND SOUTH CENTRAL
GEORGIA.

FOR FRIDAY...THE MODELS SHOW WHAT LOOKS TO BE A WET AFTERNOON IN
STORE FOR THE REGION AS THE BOUNDARY REMAINS ACROSS THE CENTRAL PART
OF THE REGION. WITH PRECIPITABLE WATER VALUES PREDICTED TO SURGE
BACK TO 2.4 INCHES PLUS...EXPECT 50 TO 70 PERCENT COVERAGE OF STORMS
ACROSS NORTH FLORIDA...TAPERING DOWN TO AROUND 40 PERCENT ACROSS THE
FAR NORTHERN AREAS. FOR NOW...FELT MOST COMFORTABLE GOING WITH THE
HIGHER GFS-BASED MAV POPS FOR FRIDAY.

THE LATEST POP FORECAST THROUGHOUT THE NEXT FIVE PERIODS REPRESENTS
AN INCREASE FROM THE INHERITED SHORT TERM FORECAST...THOUGH POP
VALUES WERE NOT INCREASED AS HIGH AS VALUES SHOWN IN THE LOCALLY
DERIVED CONFIDENCE GRIDS.

TEMPERATURES ON WEDNESDAY WILL CONTINUE TO BE QUITE HOT...ESPECIALLY
OVER THE WESTERN AREAS WHERE NEARLY FULL SUNSHINE WILL WARM
TEMPERATURES INTO THE MID AND UPPER 90S. BY THE LATTER PART OF THE
PERIOD...AFTERNOON CONVECTIVE ACTIVITY SHOULD KEEP TEMPERATURES HELD
IN THE UPPER 80S AND LOWER 90S...ESPECIALLY IN NORTH FLORIDA.

.LONG TERM...FRIDAY NIGHT THROUGH WEDNESDAY.
THE EXTENDED PERIOD BEGINS WITH TROFS ALONG BOTH THE EASTERN AND
WESTERN U.S. COASTLINES. ACROSS THE NATIONS MID SECTIONS...DEEP
LAYER RIDGING HAS A FIRM GRASP. AT THE SURFACE...THE PESKY QUASI
STATIONARY FRONT THAT WILL HAVE BEEN HUNG UP ACROSS THE REGION FOR
SEVERAL DAYS WILL PUSH SOUTH AS HIGH PRESSURE BUILDS ACROSS THE
EASTERN THIRD OF THE U.S. THROUGH THE WEEKEND...UPPER LEVEL RIDGE IS
FORECAST TO MOVE EASTWARD ACROSS THE EASTERN HALF OF THE NATION IN
RESPONSE TO A DEEPENING TROF ALONG THE WESTERN U.S. HIGH PRESSURE AT
THE SURFACE WILL GRADUALLY SLIDE NORTHEAST PLACING THE LOCAL AREA
UNDER AN EASTERLY FLOW REGIME. BY THE BEGINNING OF NEXT WEEK...UPPER
RIDGE FLATTENS A BIT AND SPREADS WESTWARD AS THE TROF FROM THE
WESTERN U.S. ROTATES UP AND OVER THE RIDGE. THE SURFACE RIDGE IS
FORECAST TO HOLD ITS PLACE THROUGH THE FIRST PART OF THE
WEEK...POSITIONED ACROSS THE EASTERN U.S. THIS KEEPS THE LOCAL
REGION UNDER EASTERLY FLOW.

WHAT THIS MEANS FOR US IS A WARMING TREND THROUGH THE EXTENDED
PERIOD AS THE UPPER RIDGE BUILDS EAST. HIGHS WILL CLIMB TO NEAR
CLIMO OR SLIGHTLY HIGHER EACH AFTERNOON. THE AFTERNOONS EACH WILL
HOLD A THREAT FOR SUMMER TIME SEA BREEZE ACTIVITY. WILL KEEP POPS
NEAR OR SLIGHTLY BELOW CLIMATOLOGY FOR THE EXTENDED PERIOD.

&&

.MARINE...THE LOCAL PRESSURE GRADIENT REMAINS RELATIVELY TIGHT
ACROSS THE COASTAL WATERS OF THE NORTHEASTERN GULF OF MEXICO THIS
MORNING. WINDS NEAR CAUTIONARY CRITERIA CONTINUE OVER THE WATERS
NEAR THE SUWANNEE RIVER ENTRANCE. THIS IS EXPECTED TO SUBSIDE LATER
TODAY...WITH WINDS GENERALLY REMAINING IN THE 10 TO 15 KNOT RANGE.
BY LATE IN THE WEEKEND...MODEL GUIDANCE IS INDICATING THE FRONTAL
BOUNDARY WILL BE PUSHED SOUTHWEST OF THE MARINE AREA PLACING THE
AREA IN A STRONG EAST-NORTHEASTERLY FLOW REGIME WITH THE POTENTIAL
FOR EXERCISE CAUTION AND POSSIBLY ADVISORY CONDITIONS STARTING
SUNDAY AND CONTINUING INTO NEXT WEEK.

&&

.AVIATION...FOG AND LOW CIGS ARE A CONCERN FOR THE EARLY MORNING
HOURS. AS OF 06Z KVLD WAS ALREADY EXPERIENCING IFR CIGS WITH
ISOLATED LOW CIGS ELSEWHERE ACROSS THE REGION. EXPECT KABY AND KVLD
TO DROP TO LIFR OR VLIFR BY SUNRISE. AT THIS TIME WILL KEEP KTLH IN
LOW END MVFR CIGS FROM PRE DAWN THROUGH THE EARLY MORNING HOURS.
THIS MAY NEED TO BE UPDATED TO IFR OR LOWER DEPENDING ON HOW FAR
WEST THE LOW CIGS EXTEND. ELSEWHERE...COASTAL LOCATIONS ALONG THE
EASTERN PANHANDLE ARE EXPERIENCING SHOWER AND ISOLATED THUNDERSTORM
ACTIVITY AS A RESULT OF THE ONSHORE FLOW IN THESE AREAS. EXPECT
MORNING SHOWERS AND ISOLATED THUNDERSTORMS TO CONTINUE ALONG COASTAL
LOCATIONS PRIMARILY ACROSS THE EASTERN PANHANDLE AND EASTERN BIG
BEND OF FLORIDA. BY EARLY AFTERNOON...ALL LOCATIONS ARE FORECAST TO
RETURN TO VFR CONDITIONS. SHOWERS AND THUNDERSTORMS ARE POSSIBLE
LATE THIS AFTERNOON WITH THE GREATEST THREAT REMAINING ALONG A LINE
FROM KVLD TO KTLH SOUTHEASTWARD.

&&

.FIRE WEATHER...ALTHOUGH DRYING IS FORECAST FOR THE NEXT COUPLE OF
DAYS...RH LEVELS WILL REMAIN ABOVE CRITICAL LEVELS THROUGH THE
WEEKEND AND BEYOND.

&&

.PRELIMINARY POINT TEMPS/POPS...
TALLAHASSEE   93  75  92  73  91 /  20  20  50  40  60
PANAMA CITY   91  76  90  73  88 /  20  20  50  40  60
DOTHAN        97  73  92  73  91 /  10  10  30  30  50
ALBANY        94  74  92  73  92 /  10  10  30  30  40
VALDOSTA      92  75  92  74  91 /  30  20  50  30  50
CROSS CITY    90  75  90  71  90 /  50  30  60  40  60
APALACHICOLA  89  77  88  73  89 /  30  30  60  40  60

&&

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

&&

LONG TERM/AVIATION/FIRE WEATHER...HARRIGAN/WOOL
REST OF DISCUSSION...GODSEY

HAZARDOUS WEATHER OUTLOOK
NATIONAL WEATHER SERVICE TALLAHASSEE FL
858 PM EDT TUE AUG 24 2010

ALZ065>069-FLZ007>019-026>029-034-108-112-114-115-118-127-128-134-
GAZ120>131-142>148-155>161-GMZ730-750-755-765-770-775-260100-
COFFEE-DALE-HENRY-GENEVA-HOUSTON-INLAND WALTON-CENTRAL WALTON-
HOLMES-WASHINGTON-JACKSON-INLAND BAY-CALHOUN-INLAND GULF-
INLAND FRANKLIN-GADSDEN-LEON-INLAND JEFFERSON-MADISON-LIBERTY-
INLAND WAKULLA-INLAND TAYLOR-LAFAYETTE-INLAND DIXIE-SOUTH WALTON-
COASTAL BAY-COASTAL GULF-COASTAL FRANKLIN-COASTAL JEFFERSON-
COASTAL WAKULLA-COASTAL TAYLOR-COASTAL DIXIE-QUITMAN-CLAY-
RANDOLPH-TERRELL-DOUGHERTY-LEE-WORTH-TURNER-TIFT-BEN HILL-IRWIN-
EARLY-MILLER-BAKER-MITCHELL-COLQUITT-COOK-BERRIEN-SEMINOLE-
DECATUR-GRADY-THOMAS-BROOKS-LOWNDES-LANIER-
APALACHEE BAY OR COASTAL WATERS FROM KEATON BEACH TO OCHLOCKONEE
RIVER FL OUT TO 20 NM-
COASTAL WATERS FROM APALACHICOLA TO DESTIN FL OUT 20 NM-
COASTAL WATERS FROM  OCHLOCKONEE RIVER TO APALACHICOLA FL OUT TO
20 NM-
COASTAL WATERS FROM  SUWANNEE RIVER TO KEATON BEACH OUT 20 NM-
WATERS FROM APALACHICOLA TO DESTIN FL FROM 20 TO 60 NM-
WATERS FROM  SUWANNEE RIVER TO APALACHICOLA FL FROM 20 TO 60 NM-
858 PM EDT TUE AUG 24 2010 /758 PM CDT TUE AUG 24 2010/

THIS HAZARDOUS WEATHER OUTLOOK IS FOR SOUTHEAST ALABAMA...
SOUTHWEST AND SOUTH CENTRAL GEORGIA...AND THE FLORIDA BIG BEND
AND PANHANDLE...AND ADJACENT COASTAL WATERS.

.DAY ONE...TONIGHT...
ISOLATED SHOWERS AND THUNDERSTORMS WILL GRADUALLY DISSIPATE
THROUGH MIDNIGHT EDT...11 PM CDT...EXCEPT FOR TAYLOR AND DIXIE
COUNTIES AND ADJACENT COASTAL WATERS...WHERE ISOLATED SHOWERS MAY
CONTINUE INTO THE EARLY MORNING HOURS. PATCHY DENSE FOG WILL BE
POSSIBLE EARLY WEDNESDAY MORNING. OTHERWISE...HAZARDOUS WEATHER IS NOT
EXPECTED.

.DAYS TWO THROUGH SEVEN...WEDNESDAY THROUGH MONDAY...
COVERAGE OF SHOWERS AND STORMS WILL INCREASE ONLY VERY SLIGHTLY
FOR WEDNESDAY AND THURSDAY BEFORE FALLING BACK TO BELOW NORMAL
LEVELS FOR THE WEEKEND AND INTO EARLY NEXT WEEK. NO ORGANIZED
SEVERE WEATHER IS EXPECTED.

.SPOTTER INFORMATION STATEMENT...
SPOTTER ACTIVATION IS NOT ANTICIPATED.

FOR ADDITIONAL INFORMATION...VISIT THE NATIONAL WEATHER SERVICE
WEBSITE ON THE INTERNET AT WEATHER.GOV...THEN CLICK ON YOUR AREA
OF INTEREST ON THE NATIONAL MAP.

FOURNIER/WOOL