FXUS62 KTAE 250852
AFDTAE
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE TALLAHASSEE FL
400 AM EST FRI DEC 25 2009
.SYNOPSIS...WITH BOTH THE SFC AND UPPER LEVEL LOW PRESSURE SYSTEMS
EJECTING QUICKLY OFF TO THE N-NW TOWARDS THE MID MS RIVER VALLEY
EARLY THIS MORNING...THE THREAT FOR ANY SEVERE WX IS DIMINISHING
ACROSS THE ALL BUT EASTERNMOST PORTIONS OF THE CWA...AND ALTHOUGH
THE ENVIRONMENTAL WINDS REMAIN QUITE STRONG...THE LACK OF
INSTABILITY IS ONLY ALLOWING FOR ISOLATED THUNDERSTORMS...WHICH IS
PREVENTING THESE VERY STRONG WINDS FROM MIXING DOWN TO THE SFC.
NONETHELESS...WE ARE STILL OBSERVING A FAIRLY HEALTHY BAND OF
SHOWERS OUT AHEAD OF THE FRONT WITH SFC WINDS GUSTING TO 30 TO 35
MPH IN MANY LOCATIONS. OVER THE COASTAL WATERS...WINDS AND SEAS
REMAIN ELEVATED AT GENERALLY HIGH END SCA LEVELS...AND DUR TO THE
HIGH SWELLS...SEAS ARE STILL NOT EXPECTED TO DROP BELOW THE 7 FOOT
THRESHOLD UNTIL EARLY SATURDAY MORNING WHEN THE SFC RIDGE BUILDS IN
OVER THE CWA.
&&
.SHORT TERM (TODAY THROUGH SUNDAY)...EXPECT THE SCT SHOWERS AND
ISOLD TSTMS TO END FROM WEST TO EAST ACROSS THE REGION DURING THE
MORNING HOURS...WITH COOLER AND DRIER AIR BUILDING IN BEHIND THE
COLD FRONT THIS AFTERNOON. FOR TONIGHT...ALTHOUGH SOME OF THE
NUMERICAL GUIDANCE IS INDICATING A SHORT PERIOD OF BELOW FREEZING
TEMPERATURES ACROSS NORTHWEST PORTIONS OF THE CWA...HAVE CURRENTLY
CAPPED LOWS AT THE FREEZING MARK FOR THE TIME BEING DUE TO THE
LIKELY HIGH SOIL MOISTURE CONTENT FROM TONIGHT'S RAINFALL. IF THE
GUIDANCE CONTINUES TO TREND DOWNWARD...HOWEVER...THE DAY SHIFT MAY
NEED TO RE-EXAMINE LOWS AND CONSIDER THE POTENTIAL FOR SOME FROST...
OR AT THE VERY WORST...A LIGHT FREEZE ACROSS PARTS OF THE AREA. BY
SATURDAY NIGHT AND SUNDAY...A WEAK WAVE OF LOW PRESSURE IS EXPECTED
TO MOVE ACROSS THE NORTHERN GULF OF MEXICO...AND MAY BRING A PERIOD
OF COLD LIGHT RAIN TO THE REGION...WITH THE GFS AND NAM KEYING ON
THIS POSSIBILITY MUCH MORE THAN THE LATEST RUN OF THE ECMWF.
THEREFORE...HAVE CAPPED POPS IN THE 20-30 PERCENT RANGE FOR THE TIME
BEING.
LONG TERM...(MONDAY THROUGH FRIDAY).
THE OVERALL LONG TERM PERIOD IS DOMINATED BY FAST MID LEVEL FLOW
ACROSS THE EASTERN CONUS AND GENERALLY BELOW NORMAL TEMPERATURES.
THE PERIOD BEGINS WITH A DEEP TROF OVER THE EASTERN CONUS WITH
RELATIVELY COOL AIR IN PLACE ACROSS MUCH OF THE EAST. THE TROF AXIS
SWINGS THROUGH THE REGION MONDAY MORNING...AND MIGHT PROVIDE ENOUGH
FORCING FOR A FEW ISOLATED SHOWERS...BUT WITH THE AIRMASS PROGGED TO
BE QUITE DRY...WILL KEEP POPS OUT OF THE FORECAST FOR NOW.
COLD HIGH PRESSURE BUILDS IN ACROSS THE REGION ON MONDAY AFTERNOON
AND REMAINS IN PLACE UNTIL WEDNESDAY MORNING. BOTH THE 25/00Z EURO
AND GFS SHOW A GULF LOW DEVELOPING ALONG THE TEXAS COAST ON
WEDNESDAY AFTERNOON...THOUGH THE MODELS DIFFER ON THE TRACK AND
SPEED OF THIS FEATURE...WITH THE GFS BEING THE SLOWER OF THE TWO.
WITH THE GFS GENERALLY BEING A LITTLE FASTER IN THE DAY 5 PERIOD AND
BEYOND...WILL TREND THE GFS SOLUTION A LITTLE CLOSER TO THE EURO
PROG...BUT FAVOR A STORM TRACK SLIGHTLY FURTHER SOUTH...WHICH KEEPS
OUR REGION SQUARELY IN THE STABLE CONTINENTAL AIRMASS.
THE EURO IS SHOWING THE POTENTIAL FOR A BIG COOL AIR OUTBREAK BY THE
END OF THE PERIOD AND EXTENDING INTO THE WEEKEND. THE GFS GENERALLY
VECTORS THE MUCH COOLER AIR INTO THE MID ATLANTIC. DUE TO
UNCERTAINTIES AT THESE TIME SCALES...WILL GENERALLY STAY CLOSE TO
SLIGHTLY BELOW CLIMO VALUES...BUT IF FUTURE MODEL RUNS TREND TOWARD
THE EURO SOLUTION...TEMPERATURE FORECASTS FOR FRIDAY AND BEYOND WILL
NEED TO BE LOWERED SEVERAL DEGREES.
&&
.AVIATION...EXPECT GRADUALLY IMPROVING CONDITIONS FROM W TO E ACROSS
THE TAF SITES OVERNIGHT AND TODAY...BUT WILL HAVE TO KEEP AN EYE ON
THE LOW CLOUD DECK IN THE COLD POOL FROM THE UPPER LEVEL LOW OFF TO
OUR WEST...AS SOME OF THIS CLOUDINESS COULD IMPACT THE WESTERN
LOCATIONS IF IT SURVIVES ITS EASTWARD TREK BEFORE LIFTING AND
DISSIPATING AS THE UPPER LOW PULLS FURTHER AWAY.
&&
.MARINE...AS MENTIONED ABOVE...WINDS WILL DIMINISH QUITE A BIT MORE
QUICKLY THAN SEAS DUE TO THE LONG FETCH DURATION OUT OF THE S-SE
DEEP INTO THE GULF OF MEXICO...SO WILL NEED TO CARRY THE SMALL CRAFT
ADVISORY UNTIL 7 PM TODAY FOR APALACHEE BAY AND 7 AM SATURDAY FOR
THE OFFSHORE LEGS.
&&
.FIRE WEATHER...ALTHOUGH CONDITIONS WILL BE MUCH DRIER ACROSS THE
REGION ON SATURDAY...VERY COOL TEMPERATURES SHOULD LIMIT ANY
DURATIONS OF 35 PERCENT OR LOWER RELATIVE HUMIDITIES ACROSS THE
FLORIDA BIG BEND AND PANHANDLE TO NO MORE THAN 2 TO 3 HOURS AT
BEST...AND LIGHT WINDS SHOULD KEEP DISPERSIONS LOW. THEREFORE...A
STATEMENT IN REMARKS SHOULD BE SUFFICIENT.
&&
.PRELIMINARY POINT TEMPS/POPS...
TALLAHASSEE 63 35 55 36 55 / 30 0 0 10 30
PANAMA CITY 58 37 55 40 55 / 10 0 0 20 30
DOTHAN 56 32 53 37 53 / 10 0 0 20 30
ALBANY 62 32 55 35 53 / 40 0 0 10 30
VALDOSTA 67 35 56 36 55 / 50 0 0 10 20
CROSS CITY 70 36 57 37 58 / 50 0 0 10 20
APALACHICOLA 62 39 55 39 56 / 20 0 0 10 30
&&
.TAE WATCHES/WARNINGS/ADVISORIES...
AL...NONE.
GA...NONE.
FL...NONE.
HIGH SURF ADVISORY UNTIL 1 PM EST TODAY FOR FRANKLIN COUNTY.
HIGH SURF ADVISORY UNTIL 6 PM CST TODAY FOR THE FOLLOWING
ZONES: BAY...COASTAL WALTON...GULF.
GM...SMALL CRAFT ADVISORY UNTIL 7 PM EST TODAY FOR APALACHEE BAY OR
THE COASTAL WATERS FROM KEATON BEACH TO OCHLOCKONEE RIVER FL
OUT TO 20 NM.
SMALL CRAFT ADVISORY UNTIL 7 AM EST SATURDAY FOR OTHER ALL LEGS
EXCEPT APALACHEE BAY.
&&
$$
LONG TERM...GODSEY
REST OF DISCUSSION...GOULD
