000
FXUS62 KTAE 120910
AFDTAE
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE TALLAHASSEE FL
410 AM EST FRI MAR 12 2010
.SYNOPSIS...LATEST RUC ANALYSIS SHOWS BROAD CYCLONE CENTERED OVER
THE CENTRAL CONUS WITH A SHARP RIDGE OVER THE ROCKIES. WEAK
SOUTHERLY FLOW CONTINUES OVER OUR REGION IN RESPONSE TO UPSTREAM
COLD FRONT SET TO MOVE THROUGH LATER TODAY. DEWPOINTS HAVE HELD IN
THE LOW 60S ACROSS MUCH OF THE AREA WITH A SHALLOW MOIST LAYER IN
PLACE FROM THURSDAY'S RAINFALL. AS TEMPS DROP INTO THE LOWER 60S TO
UPPER 50S...EXPECT AREAS OF DENSE FOG THROUGH THE EARLY MORNING. FOG
WILL LIFT BY MID MORNING WITH SUFFICIENT SURFACE HEATING. SHOWERS
AND THUNDERSTORMS ARE IN PROGRESS ACROSS MISSISSIPPI AND ALABAMA
SURGING EASTWARD WITH AN ADVANCING COLD FRONT. ANOTHER BAND OF
STRATIFORM RAIN IS MEANDERING ACROSS THE EASTERN GULF ACROSS THE
FLORIDA PENINSULA. THOUGH PLENTY OF MOISTURE IS PRESENT...EXPECT
SHOWERS TO HOLD OFF UNTIL LATER THIS MORNING.
&&
.SHORT TERM...THE MISSOURI LOW AND ASSOCIATED TROUGH WILL CONTINUE
TO SLIDE EASTWARD. MODELS ARE IN GOOD AGREEMENT BRINGING A SHORTWAVE
IMPULSE AROUND THE BASE OF THE TROUGH AND OVER NORTHERN AND CENTRAL
ALABAMA. THIS DISTURBANCE WILL PROMOTE SHOWER AND THUNDERSTORM
DEVELOPMENT THROUGH THE DAY. IN ADDITION...CONDITIONS APPEAR
FAVORABLE FOR SOME SEVERE THUNDERSTORMS. THE MAIN THREATS FROM THESE
STORMS WILL BE LARGE HAIL AND DAMAGING WINDS...THOUGH AND ISOLATED
TORNADO CANNOT BE RULED OUT. SHOWERS AND THUNDERSTORMS WILL TRAVERSE
THE CWA FROM WEST TO EAST ENDING BY FRIDAY EVENING OVER OUR EASTERN
ZONES.
AS FOR THE SEVERE WEATHER THREAT...LATEST CONFIDENCE GRIDS FOR
FRIDAY AFTERNOON SHOW A 15 TO 20 PERCENT CHANCE OF SEVERE OVER
MAINLY SOUTHEASTERN GEORGIA WITH 10 TO 15 PERCENT PROBABILITIES
STRETCHING INTO SOUTHEAST ALABAMA AND THE EASTERN FLORIDA
PANHANDLE/WESTERN BIG BEND. GFS AND NAM SOLUTIONS SHOW 70 TO 80
KNOTS OF 0-6 KM SHEAR COMBINED WITH CAPE BETWEEN 1000 AND 1500 J/KG
OVER THIS REGION. WITH DEWPOINTS IN THE 60S AND MODESTLY STEEP LAPSE
RATES AROUND 7 C/KM LARGE HAIL WILL BE A THREAT WITH ANY PROLONGED
CELLS THAT DEVELOP. IN ADDITION...VAPOR IMAGERY AND LOCAL 00 UTC TLH
SOUNDING SHOWS DRY MID-LEVEL AIR IN ADVANCE OF THIS SYSTEM. AS
PRECIP FALLS THROUGH THIS LAYER...EVAPORATIVE COOLING MAY ENHANCE
CONVECTIVELY DRIVEN DOWNDRAFTS INCREASING THE LIKELIHOOD OF DAMAGING
WINDS REACHING THE SURFACE. ANY SUPERCELL THAT PERSISTS IN THIS
ENVIRONMENT IS LIKELY TO PRODUCE SEVERE WEATHER. AT THIS TIME...IT
APPEARS THE TORNADO THREAT WILL BE LIMITED. MODEL SOUNDINGS SHOW
LESS THAN FAVORABLE LOW LEVEL WIND SHEAR WITH SOMEWHAT SMALL
CLOCKWISE CURVED HODOGRAPHS FOR THE AFTERNOON PERIOD. SHOULD THE
SHORTWAVE ENERGY SLIDE A BIT FURTHER SOUTH AN ENHANCED LOW-LEVEL
WIND FIELD MAY YIELD MORE FAVORABLE CONDITIONS FOR TORNADIC STORMS
BUT CURRENT MODELS KEEP THE STRONGEST ENERGY NORTH OF OUR GEORGIA
AND ALABAMA ZONES. NONETHELESS...AN ISOLATED TORNADO CANNOT BE RULED
OUT WITH STRONGER CELLS THAT CAN BECOME SURFACE BASED ALLOWING THEM
TO TAP INTO SURFACE INSTABILITY.
SOME SHOWERS MAY LINGER INTO THE EVENING HOURS FRIDAY WITH
SUBSTANTIAL CLOUD COVER OVERNIGHT AND WINDS SHIFTING TO THE WEST
BEHIND THE COLD FRONT. WINDS AND SEAS OVER THE MARINE AREA WILL LEAD
TO SMALL CRAFT ADVISORY CONDITIONS OVER THE WESTERN MARINE AREA
BEHIND THE FRONT. THE STUBBORN UPPER LEVEL LOW WILL REMAIN IN PLACE
OVER THE SOUTHEAST WITH BROAD CYCLONIC FLOW AND STRONG NORTHWESTERLY
WINDS ALOFT. A BIT OF UNCERTAINTY EXISTS WITH THE POTENTIAL FOR
PRECIP AS SOME WEAK IMPULSES SLIDE NORTH OF THE CWA ON SATURDAY AND
SUNDAY. SILENT POPS HAVE BEEN PLACED ACROSS OUR GEORGIA AND ALABAMA
ZONES AND THESE MAY NEED TO BE ADJUSTED WITH FUTURE GUIDANCE.
OTHERWISE...CONDITIONS WILL BE MORE SETTLED WITH SLIGHT RAIN CHANCES
AND COOLING TEMPERATURES. MID AND UPPER LEVEL CLOUDS WILL LIKELY
PERSIST OVER THE NORTHERN HALF OF THE CWA THROUGH SUNDAY MORNING ON
THE SOUTHERN FRINGE OF THE LOW. LOW TEMPS ARE NOT EXPECTED TO BE
EXCEPTIONAL WITH ONLY LOWER 40S FORECAST SATURDAY NIGHT OVER THE
EXTREME NORTHWEST CWA AND HIGHS WILL REMAIN SEASONAL IN THE MID TO
UPPER 60S. SPRING SEEMS TO FINALLY BE RETURNING TO THE SOUTHEAST.
.LONG TERM (SUNDAY NIGHT THROUGH NEXT FRIDAY)...WEAK TROUGHING ALOFT
SUNDAY NIGHT FLATTENS TO BECOME ZONAL MONDAY THROUGH MIDDAY TUESDAY.
A SHORTWAVE THEN CROSSES THE EASTERN GULF TUESDAY NIGHT WITH MOST OF
THE ENERGY AND ASSOCIATED MOISTURE STAYING TO OUR SOUTH. MEANWHILE
AN UPPER LOW CLOSES OFF OVER EASTERN IOWA LATE TUESDAY DROPPING
SOUTHWARD TO SOUTHERN ALABAMA WEDNESDAY NIGHT DIGGING A DEEP TROUGH
THROUGH THE EASTERN GULF. THIS LOW AND ASSOCIATED TROUGH MOVES EAST
INTO THE WESTERN ATLANTIC THURSDAY WITH ZONAL FLOW RETURNING ON
FRIDAY. AT THE SURFACE...WEAK PRESSURE PATTERN WITH OFFSHORE FLOW
THROUGH TUESDAY. WINDS BACK TO THE WEST AS A THROUGH PUSHES INTO
CENTRAL GEORGIA WEDNESDAY. THIS TROUGH ALONG WITH DEEP LAYER
MOISTURE AND STRONG SHORTWAVE ENERGY SHOULD BRING AT LEAST A CHANCE
OF RAIN ACROSS OUR GEORGIA ZONES WEDNESDAY NIGHT/THURSDAY. AS THIS
SYSTEM EXITS TO OUR EAST...SURFACE HIGH PRESSURE AND A DRIER AIRMASS
BUILD IN ON FRIDAY. TEMPERATURES WILL GENERALLY BE JUST BELOW
SEASONAL NORMALS THROUGH THE PERIOD.
&&
.MARINE...A COLD FRONT WILL SWEEP THROUGH THE REGION LATER TODAY.
WIDESPREAD SHOWERS AND THUNDERSTORMS WILL BE LIKELY THIS MORNING
THROUGH THE EVENING. A FEW STORMS COULD BE SEVERE WITH LARGE HAIL
AND DAMAGING WINDS. WINDS WILL SHIFT TO WEST BEHIND THE FRONT AND
INCREASE TO AROUND 20 KNOTS BY THIS AFTERNOON. A PROLONGED PERIOD OF
HIGH SEAS AND WINDS ARE EXPECTED FOR THE MARINE AREA BEGINNING IN
THE WESTERN ZONES. FOR THIS REASON...SMALL CRAFT ADVISORIES HAVE
BEEN ISSUED FOR THE ENTIRE MARINE AREA BEGINNING FRIDAY AFTERNOON IN
THE WEST AND EARLY SATURDAY MORNING IN THE EAST AND ENDING SUNDAY.
WINDS OF 25 KNOTS WITH GUSTS TO AROUND 30 KNOTS COMBINED WITH SEAS
UP TO 10 FEET WILL BE LIKELY THROUGH SUNDAY AFTERNOON. BY
SUNDAY...CONDITIONS WILL BEGIN TO CALM AS A MORE SETTLED WEATHER
PATTERN MOVES IN.
&&
.AVIATION...ABUNDANT LOW LEVEL MOISTURE FROM THURSDAY'S RAINS ALONG
WITH LIGHT SURFACE WINDS AND CLEARING SKIES WILL RESULT IN
WIDESPREAD STRATUS AND FOG DEVELOPMENT THROUGH DAYBREAK. EXPECT
PREVAILING MVFR/IFR CIGS/VSBYS AT ALL TAF SITES WITH TEMPOS FOR LIFR
CONDITIONS AT TLH AND VLD. LIGHT RAIN OR DRIZZLE IS POSSIBLE AROUND
OR JUST AFTER DAYBREAK. INCLUDED TEMPOS FOR CONVECTION AT ALL SITES
IN THE 18Z TO 24Z TIME FRAME. SOME OF THE TSTMS MAY BE STRONG TO
SEVERE AS THEY SWEEP FROM WEST TO EAST AHEAD OF A COLD FRONT. WINDS
SHIFT TO THE WEST OR NORTHWEST BEHIND THE COLD FRONT TOWARD THE END
OF THE FORECAST PERIOD.
&&
.FIRE WEATHER...NO FIRE WEATHER CONCERNS TODAY. COOLER AND DRIER
CONDITIONS WILL RETURN THIS WEEKEND BUT AT THIS TIME IT LOOKS LIKE
AFTERNOON RELATIVE HUMIDITIES SHOULD REMAIN ABOVE CRITICAL LEVELS.
&&
.PRELIMINARY POINT TEMPS/POPS...
TALLAHASSEE 71 48 67 47 67 / 70 10 10 10 0
PANAMA CITY 69 50 65 50 64 / 70 0 10 10 0
DOTHAN 69 45 63 43 63 / 70 10 10 10 0
ALBANY 69 46 63 44 63 / 80 20 10 10 0
VALDOSTA 73 49 66 47 66 / 70 20 10 10 0
CROSS CITY 72 51 67 49 67 / 60 10 10 10 0
APALACHICOLA 68 53 65 51 63 / 60 10 10 10 0
&&
.TAE WATCHES/WARNINGS/ADVISORIES...
AL...NONE.
GA...NONE.
FL...NONE.
GM...SMALL CRAFT ADVISORY FROM 4 AM EST SATURDAY TO 11 AM EDT SUNDAY
FOR THE FOLLOWING ZONES: APALACHEE BAY OR COASTAL WATERS
FROM KEATON BEACH TO OCHLOCKONEE RIVER FL OUT TO 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 SUWANNEE RIVER TO
APALACHICOLA FL FROM 20 TO 60 NM.
SMALL CRAFT ADVISORY FROM 4 PM EST THIS AFTERNOON TO 11 AM EDT
SUNDAY FOR THE FOLLOWING ZONES: COASTAL WATERS FROM
APALACHICOLA TO DESTIN FL OUT 20 NM...WATERS FROM
APALACHICOLA TO DESTIN FL FROM 20 TO 60 NM.
&&
$$
AVIATION/FIRE WX/LONG TERM...BARRY
REST OF DISCUSSION...AUSTIN/WOOL
