FXUS62 KJAX 271948
AFDJAX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE JACKSONVILLE FL
247 PM EST FRI NOV 27 2009
...COOL AND DRY THIS WEEKEND...
.SHORT TERM...TONIGHT THROUGH MON...
SURFACE HIGH PRESSURE OVER THE CENTRAL GULF COAST STATES WILL
CONTINUE TO BUILD EAST TONIGHT AND WILL CENTER ACROSS THE JAX CWA
SAT NIGHT. ALOFT STRONG COLD AIR ADVECTION ON NW WINDS WILL DECREASE
THIS AFTN INTO TONIGHT AS FLOW BECOMES MORE ZONAL WHILE STEERING A
DECENT CIRRUS PLUME NOW OVER THE GOMEX ACROSS OUR ZONES TONIGHT
THROUGH SAT. ALTHOUGH THE LOW LEVELS WILL REMAIN DRY DUE TO STRONG
SUBSIDENCE...PASSING MID AND HIGH CLOUDS MAY MAKE FOR PARTLY CLOUDY
SKIES AT TIMES. THE MAIN SHORT TERM FORECAST CHALLENGE WILL BE
EXTENT OF FROST DEVELOPMENT TONIGHT AND SAT NIGHT. GIVEN PASSING
HIGH CLOUDS TONIGHT AND DEW PT DEPRESSIONS AROUND 4-7 DEG...DECIDED
NOT TO GO WITH AN ADVISORY AT THIS TIME AND CONTINUE WITH AREAS OF
FROST INLAND WITH PATCHY TOWARD THE COAST. SIMILAR SCENARIO
ADVERTISED FOR SAT NIGHT AT THIS TIME...BUT CONDITIONS APPEAR MORE
FAVORABLE FOR FROST/BR DEVELOPMENT DUE TO LESS UPPER LEVEL
MOISTURE...STRONGER SURFACE SUBSIDENCE...AND SMALLER DEW PTS
DEPRESSIONS. NOT EXPECT A WIDESPREAD FREEZE EVENT TONIGHT...BUT
HIGHLY LIKELY SOME OF OUR NORMALLY COLDER LOCATIONS IN GA AND THE
SUWANNEE RIVER VALLEY WILL FALL INTO THE LOWER 30S. TEMPS BEGIN TO
REBOUND SAT WITH HIGHS IN THE MID 60S...THEN MINS SAT NIGHT IN THE
MID/UPR 30S. FURTHER MODIFICATION ON SUN AS LIGHT SOUTHERLY FLOW
DEVELOPS AS THE SURFACE RIDGE SHIFTS OFFSHORE OF THE FL PENINSULA.
LATE MON A WEAK FRONT WILL APPROACH THE AREA AS UPPER LEVEL DYNAMICS
SHIFT NORTH OF THE AREA AND INSTABILITY REMAINS WEAK. WILL CONTINUE
TO ADVERTISE A LOW CHANCE OF SHOWERS LATE MON AFTN ACROSS OUR NW GA
ZONES...THEN A LOW CHANCE MON NIGHT ACROSS THE CWA AS THE FRONT
BEGINS TO STALL.
.LONG TERM...TUE THROUGH FRI...
A CUT-OFF LOW OVER TX WILL BEGIN TO TRANSLATE EASTWARD TUE WHICH
WILL INDUCE SFC CYCLOGENESIS IN THE GOMEX TUESDAY. AS THE SFC LOW
APPROACHES LATE TUE INTO WED...THE STALLED FRONT ACROSS N-CENTRAL FL
WILL LIFT NORTHWARD AS A WARM FRONT...LIKELY DISSECTING OUR CWA FROM
SSI TOWARD LCQ BY WED MORNING WITH OUR SOUTHERN ZONES IN THE WARM
SECTOR. STRONG SHEAR WILL BE IN PLACE WITH MODEST SFC BASED
INSTABILITY ALONG AND SOUTH OF WARM FRONT WITH DEW PTS INT HE
LOW/MID 60S. THE GFS40 DEPICTS THE SFC LOW A BIT TOO FAR DOWNSTREAM
FROM THE PARENT UPPER LEVEL LOW...SO PREFER A DGEX/ECMWF SOLUTION
THAT KEEPS THE LOW LEVEL CIRCULATION CLOSER TO THE UPPER VORTEX
SOUTH OF LA ON WED AT 12Z...THEN TRACKS RE-DEVELOPS THE SYSTEM
OFFSHORE OF THE SE ATLANTIC COAST WED EVENING/THU NIGHT WITH A
TRAILING COLD FRONT CROSSING THE AREA WED AFTN. DEFINITE POTENTIAL
FOR SEVERE WEATHER WED ASSOCIATED WITH THIS SYSTEM...AND WILL
CONTINUE TO HIGHLIGHT THIS IN THE HAZARDOUS WEATHER OUTLOOK. COOLER
AND DRIER CONDITIONS FRI AS SFC HIGH REBUILDS OVER THE GULF COAST
STATES.
&&
.AVIATION...VFR CONDITIONS.
&&
.MARINE...DROP SCA OFFSHORE AND REPLACED WITH SCEC WITH BUOY 41008
SUSTAINED AROUND 16 KTS WITH 4 FT SEAS AND BUOY 41012 SUSTAINED AT
14 KTS (GUSTS TO 21 KTS) AND SEAS AROUND 6 FT. WINDS/SEAS WILL
CONTINUE TO RELAX TONIGHT INTO THE WEEKEND...THEN FOLLOWING WEAK
FROPA MON AND TIGHTENING PRESSURE GRADIENT IN ADVANCE OF GULF
LOW...WINDS INCREASE TO SCA LEVELS TUESDAY WITH GALES POSSIBLE ON
WED. CAPPED WINDS AT 25 KTS FOR NOW UNTIL GUIDANCE IS IN BETTER
AGREEMENT.
&&
.FIRE WEATHER...ALMOST MARGINAL RFW CONDITIONS ACROSS NE FL THIS
HOUR WITH HUMIDITIES JUST NOW DROPPING TO 33% AT JAX...WITH VALUES
FARTHER INLAND AROUND 35-40%. WILL CONTINUE RFW AS IS FOR
TODAY...AND LEFT FIRE WX WATCH AS IS FOR SATURDAY BUT DID INCLUDE
CLAY COUNTY. SUSPECT THAT RH'S WILL FALL TO CRITICAL LEVELS SAT
AFTN...BUT DURATIONS ARE QUESTIONABLE...SO WILL LET LATER SHIFTS
DECIDED IF AN UPGRADE TO A RED FLAG WARNING IS NEEDED.
&&
.PRELIMINARY POINT TEMPS/POPS...
AMG 33 64 36 70 / 0 0 0 0
SSI 40 61 46 68 / 0 0 0 0
JAX 37 64 38 72 / 0 0 0 0
SGJ 42 63 44 72 / 0 0 0 0
GNV 34 65 37 72 / 0 0 0 0
OCF 35 66 38 74 / 0 0 0 0
&&
.JAX WATCHES/WARNINGS/ADVISORIES...
FL...RED FLAG WARNING UNTIL 5 PM EST THIS AFTERNOON FOR ALACHUA-BAKER-
BRADFORD-CLAY-COLUMBIA-DUVAL-FLAGLER-GILCHRIST-HAMILTON-
MARION-NASSAU-PUTNAM-ST JOHNS-SUWANNEE-UNION.
FIRE WEATHER WATCH FROM SATURDAY MORNING THROUGH SATURDAY
AFTERNOON FOR ALACHUA-BAKER-BRADFORD-CLAY-COLUMBIA-
GILCHRIST-HAMILTON-MARION-PUTNAM-SUWANNEE-UNION.
GA...NONE.
AM...NONE.
&&
$$
ENYEDI/PRESNALL
