000
FXUS62 KJAX 031930
AFDJAX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE JACKSONVILLE FL
230 PM EST WED DEC 3 2008
.SHORT TERM...TONIGHT-SATURDAY.
MODELS ARE IN GOOD AGREEMENT SHOWING PROGRESSIVE PATTERN CONTINUING
WITH WEAK RIDGING ALOFT OVER THE SE CONUS BEING REPLACED WITH
TROUGHING OVER THE NEXT FEW DAYS WITH 500 MB HEIGHTS DECREASING
OVER THE ERN U.S. AT SFC...COLD FRONT LOCATED OVER CENTRAL PLAINS
AT THIS TIME WILL SHIFT EWD QUICKLY AS STRONG VORTICITY ALOFT
PUSHES EWD THROUGH TX AND THEN SE CONUS THROUGH THU. THE SFC FRONT
WILL PUSH INTO GA AND WRN FL PANHANDLE BY THU NIGHT WITH POPS
GRADUALLY INCREASING OVER THE NW ZONES. BEST POPS EXPECTED BY FRI
AS THE FRONT SLOWS AND PUSHES INTO THE AREA. MOISTURE AND DYNAMICS
ARE LIMITED AND SO WILL NOT GO AS QUITE AS HIGH AS THE MAV
GUIDANCE AT THIS TIME WITH 20-40% PLANNED WITH A N-S POP GRADIENT.
FRONT SHOULD PUSH INTO NE FL BY FRI NIGHT WITH 20-30% POPS AS
ANOTHER SHORTWAVE TROUGH AXIS MOVES TO TN TO LOWER MS VALLEY.
TEMPS TONIGHT EXPECTED IN THE MID 30S TO LOWER 40S WITH PATCHY
FROST INLAND AND SHALLOW PATCHY FOG OVER ERN ZONES. WARMER MAX
TEMPS IN THE UPPER 60S TO AROUND 70 FOR THU WITH GOOD SLY FLOW
DEVELOPING AHEAD OF THE FRONT. INCREASED CLOUD COVER AND PRECIP
SHOULD YIELD SOMEWHAT COOLER TEMPS FOR FRI AND FRI NIGHT.
SATURDAY...FRONT MAY TEMPORARILY STALL OVER THE SE ZONES WITH
WEAK OVERRUNNING CREATING SLOW CLEARING SKIES THERE. SATURDAY
NIGHT...LOW AND MID LEVEL TROUGH FINALLY PUSHES THROUGH THE CWA WITH
CLEARING SKIES AND COOLER TEMPS EXPECTED IN THE UPPER 30S TO MID
40S.
.LONG TERM...SUNDAY-WEDNESDAY.
SFC HIGH PRESSURE WILL BUILD INTO THE AREA FROM THE NW SUNDAY AND
MONDAY BEHIND THE DEPARTING COLD FRONT...WITH THE CENTER OF THE HIGH
MOVING E TOWARD THE CAROLINAS AND VA BY MONDAY. THIS SHOULD HELP
ENHANCE AIRMASS MODIFICATION WITH ELY LOW LEVEL FLOW DEVELOPING
QUICKLY. BY TUESDAY...GLOBAL MODELS ARE IN FAIRLY GOOD AGREEMENT
SHOWING A STRONG SHORTWAVE TROUGH DEVELOPING OVER THE S CENTRAL
PLAINS PRODUCING SFC CYCLOGENESIS OVER THE LOWER MS VALLEY AREA.
THIS WILL HELP ENHANCE GULF INFLUX OF MOISTURE TUE AND WED FOR THE
AREA. HAVE GONE WITH 20-30% POPS FOR NOW WITH NO MENTION OF ANY
TSTMS YET AS PROBABILITIES AT THIS TIME ARE ABOUT 5-10%.
&&
.AVIATION...VFR CONDITIONS THROUGH MIDNIGHT TONIGHT. THEN MAIN
CHALLENGE WITH TAFS TONIGHT IS POSSIBILITY OF SHALLOW FOG BECOMING
THICK ENOUGH TO PROMOTE IFR VSBYS BTWN 09-13Z THU MORNING. GFS/LAMP
GUIDANCE ALL OVER THE PLACE FROM VFR TO LIFR POSSIBILITIES...BUT FOG
STABILITIES FROM UPS FOG TECHNIQUE ARE VERY HIGH SUGGESTING A STRONG
INVERSION AND GOOD SET-UP FOR FOG...THE MAIN MISSING INGREDIENT IS
LOW LEVEL MOISTURE WHICH HAS NOT BEEN FORECAST WELL BY THE MODELS
TODAY...BUT WITH MOIST GROUND POSSIBLY PROVIDING SOME FEEDBACK INTO
THE LOWER LEVELS...HAVE OPTED FOR SOME MVFR VSBYS IN ALL TAF SITES
WITH SOME TEMPO IFR VSBYS BTWN 09-13Z. AFTER EARLY MORNING
FOG...CUMULUS RULE SUGGESTING AT LEAST SCT CU DEVELOPMENT AFTER 15Z
AT ALL TAF SITES.
&&
.MARINE...
LIGHT WINDS (10 KTS OR LESS) AND FLAT SEAS (3 FT OR LESS) EXPECTED
THROUGH FRIDAY AND HAVE COMBINED THE NEARSHORE AND OFFSHORE LEGS
INTO ONE GROUP. A BRIEF INCREASE TO N/NW WINDS TO 10-15 KNOTS AND
SEAS OF 3-5 FT POSSIBLE ON SATURDAY BEHIND 1ST FRONTAL PASSAGE BUT
BIGGER INCREASE ON SUNDAY TO N/NW WINDS TO 15-20 KNOTS AND SEAS OF 4
TO 6 FT LIKELY WITH SECONDARY FRONTAL PASSAGE WHICH WILL CONTINUE
INTO MONDAY BEFORE SWITCHING TO STRONG SOUTHERLY WINDS AHEAD OF NEXT
FRONT ON TUE/WED TIMEFRAME.
&&
.FIRE WEATHER...
VERY MARGINAL RED FLAG EVENT STILL IN PLACE ALONG THE I-75 CORRIDOR
OF INLD NERN FL...WITH MOST RH VALUES IN THE 35-40% RANGE AND ONLY A
FEW DOWN AROUND 30%. FOR NOW WILL LET RED FLAG PLAY OUT UNTIL ITS
5PM EXPIRATION TIME. NO FURTHER RED FLAG EVENTS ARE POSSIBLE UNTIL
AFTER THE NEXT FRONTAL PASSAGE ON SUNDAY/MONDAY AND EVEN THEN THEY
APPEAR MARGINAL AT BEST.
&&
.PRELIMINARY POINT TEMPS/POPS...
AMG 32 67 45 59 / 0 0 30 40
SSI 44 65 53 63 / 0 0 10 30
JAX 37 68 47 67 / 0 0 10 30
SGJ 43 67 49 68 / 0 0 10 10
GNV 37 70 47 69 / 0 0 10 20
OCF 38 71 47 72 / 0 0 10 10
&&
.JAX WATCHES/WARNINGS/ADVISORIES...
FL...RED FLAG WARNING UNTIL 5 PM EST THIS AFTERNOON FOR ALACHUA-BAKER-
BRADFORD-COLUMBIA-GILCHRIST-HAMILTON-MARION-SUWANNEE-UNION.
GA...NONE.
AM...NONE.
&&
$$
SHASHY/HESS/KEEGAN
