FXUS62 KJAX 260922
AFDJAX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE JACKSONVILLE FL
415 AM EST SAT DEC 26 2009
.SHORT TERM (SAT-MON)...CLOUDY SKIES OVER THE AREA THIS MORNING
AS A RESULT OF MOISTURE TRAPPED BELOW SHARP INVERSION AT 900 MB
AND HIGH CLOUDS FROM SUB TROPICAL JET. COOL HIGH PRESSURE BUILDS
INTO THE AREA FROM THE GULF COAST TODAY AND SHOULD SEE THE LOW
CLOUDS BREAK THIS AM BUT THE HIGH CLOUDS WILL CONTINUE OVER THE AREA
TODAY. WITH THE HIGH CLOUD COVER AND WEAK COLD AIR ADVECTION HIGH
TEMPS THIS AFTERNOON ONLY REACHING THE MID TO UPPER 50S ACROSS SE GA
AND AROUND 60 ACROSS NE FL. COOL NIGHTS IN STORE BUT NO FREEZES
EXPECTED WITH MINS IN THE MID 30S WELL INLAND AND 40 TO 45 NEAR THE
COAST. A WEAK SURFACE WAVE PASSES SOUTH OF THE AREA SUNDAY BRINGING
A SLIGHT CHANCE OF RAIN TO NE FL FOLLOWED BY ANOTHER SURGE OF COOLER
AND DRIER AIR MONDAY. CONTINUED COOL WITH THE HIGH CLOUDS THINNING
OUT SOME SUN-MON.
.LONG TERM (TUE-NEW YEARS DAY)...A COLDER AND DRIER AIRMASS MOVES
INTO THE REGION TUE AS A MID/UPPER TROUGH AMPLIFIES ACROSS THE NE
U.S. AND STRONG (1030 MB) SFC HIGH BUILDS NORTH OF THE AREA.
MAY HAVE A LIGHT FREEZE EARLY TUE AM MOST INLAND AREAS AWAY FROM
THE RIVER AND COAST FOLLOWED BY AN UNSEASONABLY COOL DAY ALL AREAS.
MOST OF THE LONG TERM WILL HAVE BELOW NORMAL TEMPS BUT NO FREEZES
EXPECTED AFTER TUE AS THE LONG WAVE TROUGH ALONG THE NE U.S. QUICKLY
MOVES EAST AND THE AIRMASS MODIFIES SOME. GOOD AGREEMENT BETWEEN THE
GFS AND ECMWF WITH SFC LOW DEVELOPING ALONG WESTERN GULF MID WEEK
BUT MAJOR DIFFERENCES IN TIMING WHEN SYSTEM TRACKS ACROSS THE AREA
WITH THE GFS BEING MUCH FASTER. FOR NOW...HAVE TAKING A BLEND OF
THE MODELS AND PREVIOUS FORECAST AND HAVE CHC POPS WED NIGHT INTO
THU NIGHT FOLLOWED BY POPS LOWERING FROM NW-SE NEW YEARS DAY.
&&
.AVIATION...HIGH CLOUDS ON IR SATELLITE IMAGERY MADE IT DIFFICULT
TO SEE THE LOW CLOUDS DEVELOPING BUT OBSERVATIONS AND SOME CLEARING
OF THE CIRRUS CANOPY SHOW SOME FAIRLY LARGE AREAS OF LOW CLOUDS
NEAR 1500-2500 FT OVER THE FL TAF SITES. MODELS HAVE NOT HANDLED
THE SET UP WELL AND WERE TOO FAST WITH ADVECTING IN DRY AIR.
ANTICIPATE MVFR CIGS AT TIMES THROUGH ABOUT 12Z BUT SECTIONS LAST TO
CLEAR OUT OF LOW CLOUDS WILL BE SE OF A LINE FROM GNV TO JAX
PER RUC 285K RH PROGS. HAVE AMENDED TAFS TO ACCOUNT FOR THE
CIGS. OTHERWISE...FOR LATER THIS MORNING AND THIS AFTERNOON...
VFR WITH NWLY WINDS AT 10 KT OR LESS. WILL CONTINUE TO SEE
BROKEN HIGH CLOUDS THROUGH TONIGHT.
&&
.MARINE...WINDS AND SEAS MAY BE A TAD ABOVE GUIDANCE. 41012 IS
NW16G21KT AND SEAS OF 6-7 FT AT 09Z. FOR THIS REASON AND THE BASED ON
NEW WAVE GUIDANCE WILL EXTEND SCA FOR THE OFFSHORE WATERS UNTIL
THIS AFTERNOON. WINDS AND SEAS WILL DECREASE TONIGHT AND SUN BUT
ANOTHER SFC TROUGH PUSHES THROUGH LATE SUN NIGHT AND MON INCREASING
WINDS AND SEAS AGAIN INTO TUE. HIGH PRESSURE SLIDES N OF THE
AREA TUE AND WED VEERING WINDS TO NE-E.
&&
.FIRE WEATHER...A TOUGH CALL ON LOW RH VALUES FOR THIS AFTERNOON
BUT APPEARS THAT WE WILL FALL SHORT OF REACHING DURATIONS NEEDED
FOR A RED FLAG WARNING DUE TO COOLER AIR SO HAVE ELECTED TO CANCEL
THE FIRE WEATHER WATCH AND LET DAYSHIFT MONITOR CONDS. HAVE INCLUDED
WORDING FOR LOWER RH VALUES EXPECTED TODAY IN THE FIRE WX PRODUCTS.
&&
.PRELIMINARY POINT TEMPS/POPS...
AMG 56 34 58 34 / 0 10 10 10
SSI 57 39 58 40 / 0 10 10 10
JAX 59 37 60 37 / 0 10 20 10
SGJ 59 41 60 43 / 0 10 20 20
GNV 59 36 59 38 / 0 10 20 20
OCF 61 37 58 41 / 0 10 30 20
&&
.JAX WATCHES/WARNINGS/ADVISORIES...
FL...NONE.
GA...NONE.
AM...SMALL CRAFT ADVISORY UNTIL 3 PM EST FOR ALTAMAHA SOUND
GA TO FERNANDINA BEACH FL 20 NM TO 60 NM OFFSHORE-
FERNANDINA BEACH TO ST AUGUSTINE FL 20 NM TO 60 NM OFFSHORE-
ST AUGUSTINE TO FLAGLER BEACH FL 20 NM TO 60 NM OFFSHORE.
&&
$$
PP/ARS
