FXUS62 KTAE 090824
AFDTAE
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE TALLAHASSEE FL
323 AM EST WED DEC 9 2009
.SYNOPSIS...THE MID/UPPER LEVEL TROUGH OVER THE CENTRAL PLAINS IS
BEGINNING TO TAKE ON A NEGATIVE TILT AS IT APPROACHES THE MID MS
VALLEY. THE PROFILER NETWORK REVEALS A 140-KT JET AT 250 MB MOVING
INTO THE BASE OF THIS TROUGH OVER OK. THIS WILL HELP TO ACCELERATE
THE SYSTEM RAPIDLY OFF TO THE NE AS THE MORNING PROGRESSES. SURFACE
ANALYSIS SHOWS LOW PRESSURE DEEPENING OVER IL. MID 60S DEW POINTS
HAVE SURGED NWD INTO NWRN AL. AS THE UPPER DYNAMICS LIFT FURTHER
AWAY FROM THE LOW LEVEL INSTABILITY IN THE WARM SECTOR...WE
ANTICIPATE THE CONVECTION AHEAD OF THE COLD FRONT TO BECOME LESS
VIGOROUS WITH TIME. STILL THERE WILL BE PLENTY OF DEEP AND LOW LEVEL
SHEAR IN PLACE THROUGH THE MORNING WITH BULK SHEAR VALUES OF 60-70
KT MOVING INTO OUR WRN ZONES. MLCAPE WILL BE MODEST...GENERALLY LESS
THAN 700 J/KG. THIS SHOULD PRECLUDE AN ORGANIZED SEVERE THREAT AFTER
SUNRISE. IN THE INTERIM...WE DO EXPECT A NARROW WINDOW OF
OPPORTUNITY FOR SEVERE STORMS TO SLIP INTO OUR NWRN ZONES FROM
AROUND 09Z TO ABOUT 13Z OR SO AND WE HAVE KEPT ISOLATED T+ IN THE
GRIDS DURING THE PREDAWN HOURS FOR OUR SE AL ZONES AND ADJACENT
AREAS OF SW GA AND THE FL PANHANDLE. WE HAD SOME FOG EARLIER IN THE
TLH AREA AS LOWER 70S DEW POINT AIR ADVECTED OVER THE COOL SHELF
WATERS OF THE GULF. HOWEVER...IT APPEARS THAT BOUNDARY LAYER WINDS
HAVE INCREASED SUFFICIENTLY TO LIFT THIS INTO A LOW STRATUS DECK.
&&
.SHORT TERM...TODAY THROUGH FRI.
THE ACTIVE WEATHER PATTERN WILL CONTINUE ACROSS THE FORECAST AREA
WITH ONLY BRIEF LULLS BETWEEN WEATHER MAKERS. THIS IS VERY TYPICAL
OF AN EL NINO WINTER ALONG THE GULF COAST. AS THE POTENT SHORT WAVE
TROUGH LIFTS RAPIDLY NEWD...THE UPPER LEVEL CYCLONIC FLOW WILL
BECOME INCREASING LESS AMPLIFIED WITH TIME OVER THE CONUS. THE COLD
FRONT IS EXPECTED TO MOVE INTO OUR NWRN ZONES BY MIDDAY AND CLEAR
OUR SERN ZONES BEFORE MIDNIGHT TONIGHT. THE FRONT IS THEN EXPECTED
TO STALL S OF THE FORECAST AREA AS YET ANOTHER GULF LOW DEVELOPS...
THIS ONE IN THE BAY OF CAMPECHE. WEAK FORCING FOR ASCENT WILL REMAIN
IN PLACE IN THE VICINITY OF THE FRONT AND POPS WILL LINGER THROUGH
THE NIGHT WITH HIGHEST POPS SE. BY THU AFTERNOON...A STRONG AND COLD
HIGH PRESSURE CENTER WILL BUILD EWD FROM THE MID MS TO THE TN VALLEY
AND THIS WILL FINALLY NUDGE THE FRONT FAR ENOUGH S TO REMOVE POPS
FROM ALL BUT THE SE FL BIG BEND. TEMPS ON THU WILL BE SOME 20
DEGREES COOLER THAN TODAY WITH MOST AREAS PEAKING IN THE MID 50S.
THIS WILL SET THE STAGE FOR A CHILLY NIGHT THU NIGHT WITH TEMPS
FORECAST TO BRIEFLY REACH FREEZING ALONG AND N OF A LINE FROM DHN TO
ABY. FREEZE DURATIONS APPEAR TOO BRIEF TO WARRANT A FREEZE WATCH AT
THIS TIME. THE CHILLY WEATHER WILL REMAIN IN PLACE FOR FRI. THE GULF
LOW WILL BE LIFTING NWD ACROSS THE WRN GULF BY THIS TIME AND WEAK
OVERRUNNING WILL BRING A RETURN OF SLIGHT TO LOW CHANCE POPS (FOR
LIGHT RAIN) BY FRI AFTERNOON.
.LONG TERM...FRI NIGHT THROUGH WED.
THE ACTIVE SPLIT FLOW PATTERN WILL CONTINUE THROUGH THE PERIOD WITH
THE NEXT IN A SERIES OF SOUTHERN STREAM SHORT WAVES/SURFACE LOW
PRESSURE SYSTEMS IMPACTING THE CWA FRIDAY NIGHT THROUGH SUNDAY.
THERE IS THE POTENTIAL FOR HEAVY RAINFALL WITH THIS WEEKEND SYSTEM.
THE 09/00Z GFS TRACKS THE SURFACE LOW ALONG THE GULF COAST AND
INLAND ACROSS NORTHERN FL...WITH RAIN/ISOLATED TSTORMS AFFECTING THE
CWA. THE 08/12Z EURO DEPICTED A SIMILAR SCENARIO...AND WILL REVIEW
THE 09/00Z EURO TO CONFIRM ITS CONSISTENCY WITH THE LATEST GFS.
SURFACE HIGH PRESSURE MOVES RAPIDLY EAST ACROSS THE TN VALLEY AND
CAROLINAS ON MONDAY WITH A BRIEF LULL IN THE PRECIP BEFORE THE NEXT
MORE POTENT SHORT WAVE/SURFACE COLD FRONT ADVANCES ACROSS THE GULF
AND SOUTHEASTERN STATES TUESDAY AND TUESDAY NIGHT. THERE IS THE
POTENTIAL FOR STRONG TO POSSIBLY SEVERE TSTORMS WITH THIS COLD
FRONT. MUCH COOLER AND DRIER AIRMASS WILL FINALLY BUILD INTO THE
REGION FOR WEDNESDAY.
&&
.MARINE...TODAY THROUGH SUN.
WILL LEAVE THE ADVISORY IN PLACE THROUGH 21Z. WINDS ARE NOW AT
ADVISORY LEVELS AT THE WRN BUOY (42039) AND INCREASING SLOWLY TO THE
E. SEAS HAVE INCREASED TO 6 FT. SEAS ARE FORECAST TO PEAK AT 8 FT S
OF THE PANHANDLE THIS MORNING AND PEAK AT AROUND 7 FT FURTHER E. THE
APALACHEE BAY AND KEATON TO SUWANNEE NEAR SHORE LEG WILL NOT GET
SEAS THAT HIGH...BUT THERE IS A WINDOW WHERE 20 KT WINDS WILL BE
POSSIBLE THIS MORNING INTO THE EARLY AFTERNOON HOURS. A WIND SHIFT
WILL WORK ITS WAY SLOWLY ACROSS THE WATERS TONIGHT WITH WINDS AND
SEAS DROPPING BRIEFLY BELOW HEADLINE CRITERIA. THE FRONT WILL THEN
STALL S OF THE AREA AND A STRONG AREA OF COLD HIGH PRESSURE WILL
BUILD EWD FROM TX INCREASING THE GRADIENT AND BRINGING A RETURN OF
ADVISORY CONDITIONS FOR THU INTO FRI.
&&
.AVIATION...THROUGH 06Z THU.
AREAS OF LOW CIGS AND ADVECTION FOG WILL BE A CONCERN DURING THE
OVERNIGHT PERIOD...WITH LIFR OR BELOW CONDITIONS AT KTLH. SOUTHERLY
WINDS WILL REMAIN AROUND 10 KT WITH SOME GUSTS BETWEEN 15 AND 20 KT
POSSIBLE. THROUGH THE EARLY MORNING INTO THE AFTERNOON WEDNESDAY...A
COLD FRONT WILL MOVE WEST TO EAST ACROSS THE TERMINALS. THE GREATEST
THREAT FOR THUNDERSTORMS WILL BE AT KDHN...KABY AND KPFN. WINDS WILL
SHIFT FROM WEST TO NORTHWEST AND REMAIN BREEZY. BY THE LATE
AFTERNOON WEDNESDAY...THE FRONT SHOULD CLEAR TO THE SOUTHEAST WITH
MVFR CIGS FOR KTLH AND KVLD...AND VFR ELSEWHERE.
&&
.FIRE WEATHER...NO CONCERNS FOR TODAY. SOME DRIER AIR MAKES IT INTO
OUR INLAND FL PANHANDLE ZONES ON THURSDAY AFTERNOON...WITH POSSIBLE
FOUR HOUR DURATIONS OF SUB-35 PERCENT RH. FOR THIS REASON...A WATCH
WILL BE ISSUED. ON FRIDAY AFTERNOON...AT LEAST TWO TO THREE HOURS OF
SUB-35 PERCENT RH WILL BE POSSIBLE FOR THE SAME AREAS. INCREASING
MOISTURE AND RAIN CHANCES THIS WEEKEND WILL PRECLUDE RED FLAG
CONDITIONS.
&&
.HYDROLOGY...THE CHOCTAWHATCHEE RIVER AT CARYVILLE IS SLOWLY
RECEDING AND SHOULD FALL BELOW FLOOD STAGE THIS AFTERNOON OR EARLY
EVENING. DOWNSTREAM AT BRUCE...MODERATE FLOODING CONTINUES...
ALTHOUGH THE RIVER APPEARS TO HAVE CRESTED. THE APALACHICOLA RIVER
AT BLOUNTSTOWN REMAINS ABOUT 3.5 FT ABOVE FLOOD STAGE...BUT
CONTINUES A SLOW RECESSION.
&&
.PRELIMINARY POINT TEMPS/POPS...
TALLAHASSEE 76 47 55 35 54 / 70 50 40 10 30
PANAMA CITY 74 47 57 38 58 / 60 40 20 10 30
DOTHAN 74 42 54 32 53 / 30 20 10 10 30
ALBANY 75 42 55 32 53 / 40 20 20 10 20
VALDOSTA 75 46 53 35 54 / 60 50 50 10 20
CROSS CITY 76 53 58 38 61 / 70 70 60 20 30
APALACHICOLA 75 50 58 38 55 / 70 50 50 10 30
&&
.TAE WATCHES/WARNINGS/ADVISORIES...
AL...NONE.
GA...NONE.
FL...FIRE WEATHER WATCH 18-23Z THU FOR THE FOLLOWING ZONES: BAY...
CALHOUN...COASTAL WALTON...HOLMES...INLAND WALTON...JACKSON...
WASHINGTON.
GM...SMALL CRAFT ADVISORY UNTIL 4 PM EST WED ALL ZONES.
&&
$$
AVIATION/FIRE WX/LONG TERM...JAMSKI
REST OF DISCUSSION...WOOL
