FXUS62 KJAX 301931
AFDJAX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE JACKSONVILLE FL
231 PM EST MON NOV 30 2009
.SHORT TERM...SURFACE COLD FRONT CURRENTLY IS ANGLING ACROSS CENTRAL
GEORGIA TO NEAR MOBILE AND INTO THE GULF OF MEXICO. REGIONAL DOPPLER
RADARS SHOW BROKEN LINE OF SHOWERS ASSOCIATED WITH THIS FEATURE...WITH
ISOLATED SHOWERS IN ADVANCE OF THIS FEATURE. LOCALLY... SURFACE
HIGH HAS TRANSITIONED TO OUR SOUTH/SOUTHEAST. SOUTHWESTERLY WINDS
IN CONCERT WITH PARTLY TO MOSTLY SUNNY SKIES HAVE ENABLED TEMPERATURES
TO WARM INTO THE 70S.
AFOREMENTIONED FRONTAL BOUNDARY WILL CONTINUE TO ADVANCE SOUTHEAST...
ARRIVING INTO PORTIONS OF INTERIOR SOUTHEAST EARLY THIS EVENING. THIS
FRONTAL BOUNDARY WILL CROSS THE BALANCE OF THE JACKSONVILLE COUNTY
WARNING AREA OVERNIGHT. ATMOSPHERIC MOISTURE LOOKS RATHER MEAGER
TONIGHT...BUT THERE SHOULD BE SUFFICIENT DYNAMICAL SUPPORT TO WARRANT
CHANCE POPS. AS BEEN ADVERTISED...THE ATMOSPHERE WILL REMAIN TO
STABLE TO SUPPORT THUNDERSTORM DEVELOPMENT. LOW TEMPERATURES FOR
TONIGHT WILL LIKELY RANGE FROM THE MID 40S ACROSS OUR NORTHWESTERN-
MOST ZONES IN SOUTHEAST GEORGIA TO THE UPPER 50S FOR OUR SOUTHERN-
MOST LOCALES IN NORTHEAST FLORIDA. THE MAIN WEATHER PLAYER WILL
EVOLVE OUT WEST AS AN UPPER LEVEL LOW TRAVERSES MEXICO...WITH
ATTENDANT ENERGY SPAWNING A SURFACE LOW ALONG THE TEXAS COAST.
FRONTAL BOUNDARY WILL LIKELY STALL JUST SOUTH OF THE AREA BY
DAYBREAK ON TUESDAY...WITH SURFACE HIGH ADVANCING TO OUR NORTH.
AS THE SURFACE HIGH TO OUR NORTH GRADUALLY SHIFTS OFFSHORE...THE
STALLED FRONTAL BOUNDARY WILL BEGIN TO LIFT NORTHWARD AS A WARM
FRONTAL BOUNDARY. THIS LIFTING FEATURE WILL BE THE FOCUS OF
ISOLATED TO SCATTERED COVERAGE OF SHOWERS ACROSS NORTHEAST
FLORIDA...WHILE MAINLY DRY CONDITIONS ARE FORECAST FOR SOUTHEAST
GEORGIA. MEANWHILE...STORM SYSTEM OUT WEST IS FORECAST TO FURTHER
INTENSITY WHILE TAPPING INTO GULF OF MEXICO MOISTURE...ADVANCING
ACROSS TEXAS.
TUESDAY NIGHT...SEVERAL MID-LEVEL SHORTWAVE TROUGHS WILL TRAVERSE
THE REGION...PRECEDING THE ARRIVAL OF STORM SYSTEM. THESE SHORTWAVE
TROUGHS WILL INTERACT THE LIFTING WARM FRONTAL BOUNDARY...RESULTING
IN INCREASING COVERAGE OF SHOWERS. AT THIS TIME...THE GREATEST
COVERAGE OF RAIN IS EXPECTED ACROSS SOUTHEAST GEORGIA WHERE I HAVE
INCLUDED LIKELY POPS. CANNOT RULE OUT A STRAY THUNDERSTORM ALONG
AND NORTH OF LIFTING WARM FRONT...BUT HAVE OMITTED FOR NOW AS
CONFIDENCE IS LOW ESPECIALLY GIVEN LIMITED INSTABILITY...WITH
INSTABILITY AXIS RESIDING OVER THE FLORIDA PANHANDLE AND POINTS
WEST.
WEDNESDAY...BOTH THE NAM AND GFS SOLNS CONTINUE TO SHOW DIFFERENCES
WITH THE POSITION OF THE LOW...WITH THE GFS SOLN MORE PROGRESSIVE
AND FURTHER SOUTH. MEANWHILE...THE NAM SOLN IS IN CLOSER AGREEMENT
WITH THE EUROPEAN MODEL WITH THE PLACEMENT OF SURFACE LOW OVER THE
LOWER MISSISSIPPI VALLEY AROUND 12Z WEDNESDAY. THE NAM/EUROPEAN SOLNS
THEN DEPICT THE SURFACE LOW OVER THE TENNESSEE VALLEY BY 18Z...AND
OVER THE LOWER OHIO VALLEY BY 00Z. HAVE TRENDED TOWARDS THE NAM/EUROPEAN
SOLNS...WITH MAIN PRECIP BAND ARRIVING IN THE AFTERNOON AND EARLY
EVENING. NUMERICAL MODELS CONTINUE TO SHOW IMPRESSIVE DYNAMICAL
SUPPORT AS WELL AS HIGH HELICITY VALUES TO SUGGEST STRONG TO SEVERE
THUNDERSTORMS WILL IMPACT THE AREA...ESPECIALLY AS A SQUALL LINE
PRECEDES AN APPROACHING COLD FRONT. IN ADDITION...THERE WILL BE
THE POTENTIAL FOR SUPER-CELLS TO FORM IN THE AFTERNOON AHEAD OF
CONVECTIVE LINE. WILL MAINTAIN SEVERE THUNDERSTORM WORDING IN THE
ZFP...WITH SPC INDICATING SLIGHT CHANCE OF THUNDERSTORMS FOR
WEDNESDAY.
SQUALL LINE IS FORECAST TO EXIT EAST BY WEDNESDAY EVENING...WITH
SURFACE FRONTAL PASSAGE LATE WEDNESDAY NIGHT. ESTABLISHING
NORTHWEST WINDS WILL THEN ADVECT DRIER AND MORE STABLE CONDITIONS
THROUGH THURSDAY.
.LONG TERM...ALTHOUGH SURFACE COLD FRONT IS FORECAST TO HOLD SOUTH
OF THE AREA...MAIN FORECAST CHALLENGE WILL BE DETERMINING WHERE THERE
WILL BE SUFFICIENT DYNAMICS ASSOCIATED WITH ARRIVAL OF THE POLAR
JETS-REAM TO WARRANT POPS FOR LATE FRIDAY THROUGH EARLY SATURDAY. THE
12Z GFS SOLN INDICATES LARGE SCALE ASCENT WILL RESIDE ACROSS THE
AREA WHILE THE EUROPEAN INDICATES ATTENDANT LIFT WILL HOLD TO OUR
NORTH. CONFIDENCE IS TOO LOW TO WARRANT CHANGES WITH THIS
PACKAGE...BUT WHOLESALE CHANGES IN POPS/TEMPS MAY BE WARRANTED...
ESPECIALLY WRT WARMER TEMPERATURES FRIDAY NIGHT IF THE GFS SOLN
BEGINS TO DEMONSTRATE RUN-TO-RUN CONTINUITY. MUCH COLDER
TEMPERATURES WILL ARRIVE BY SATURDAY NIGHT...IF NOT SOONER...WITH
THE POTENTIAL FOR THE 1ST FREEZE OF THE SEASON FOR PORTIONS OF THE
INTERIOR.
&&
.AVIATION...MID AND HIGH CLOUDS WILL CONTINUE TO APPROACH AND
GRADUALLY INCREASE IN COVERAGE FROM THE WNW THIS AFTN AND EVENING AS
A SURFACE FRONT (NOW OVER CENTRAL GA) CONTINUES TO EDGED SOUTHWARD.
THE FRONT WILL POSITION NEAR THE FL-GA STATELINE TONIGHT AND
CONTINUE TO PUSH SOUTHWARD TOWARD CENTRAL FL EARLY TUESDAY. WINDS
WILL SHIFT FROM WSW IN ADVANCE OF THE FRONT TO NNE BY TUE MORNING.
HAVE INDICATED MVFR CIGS BY AROUND 06-08Z FOR OUR ZONES
TONIGHT...WITH VCSH POSSIBLE FOR ALL ZONES. LATER SHIFTS MAY NEED TO
ADD TEMPO SHRA ESPECIALLY TO SSI AND THE DUVAL COUNTY FL TERMINALS
FOR A PERIOD AFTER 06Z TONIGHT...BUT WILL LET THEM EVALUATE RADAR
TRENDS TO SEE IF TEMPO FOR PRECIP NEEDS TO BE INCLUDED...AND TO FINE
TUNE TIMING.
&&
.MARINE...SCEC CONDITIONS LIKELY OFFSHORE AFTER MIDNIGHT TONIGHT
FOLLOWING FROPA. SCA CONDITIONS MAY DEVELOP OFFSHORE LATE TUESDAY
NIGHT/EARLY WEDNESDAY MORNING...BUT SINCE IT IS 3RD PERIOD AND
TIMING OF SCA STILL QUESTIONABLE...WILL DEFER HEADLINE TO LATER
SHIFTS. TIMING OF WEDNESDAY STRONG SQUALL LINE MAY BE DELAYED
SLIGHTLY UNTIL WED EVENING. COMBINED SEAS WILL LIKELY RISE TO 10
FT WELL OFFSHORE LATE WED/WED NIGHT WITH SUSTAINED SPEEDS AROUND 25
KTS AND GUSTS TO GALE FORCE LIKELY. WINDS/SEAS WILL SUBSIDE LATE FRI
AS HIGH PRESSURE BUILDS IN FROM THE GULF COAST REGION.
&&
.PRELIMINARY POINT TEMPS/POPS...
AMG 46 63 53 71 / 40 0 70 90
SSI 50 63 58 72 / 30 0 50 80
JAX 51 67 61 77 / 30 10 50 80
SGJ 56 68 65 78 / 30 20 20 50
GNV 52 71 60 78 / 30 30 20 80
OCF 56 73 63 80 / 30 30 20 80
&&
.JAX WATCHES/WARNINGS/ADVISORIES...
FL...NONE.
GA...NONE.
AM...NONE.
&&
$$
ZAPPE/ENYEDI/KEEGAN
