FXUS62 KJAX 291900
AFDJAX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE JACKSONVILLE FL
200 PM EST SUN NOV 29 2009
...THREAT FOR SEVERE WEATHER LATE WEDNESDAY...
.SHORT TERM...TNGT THRU TUES...HIGH PRESSURE OVER THE AREA MEANS A
QUIET NIGHT...POSSIBLY SOME PATCHY FOG INTERIOR PORTION OF FL
PENINSULA. FOR MON...UPR TROF PASSES TO THE NORTH OF THE REGION...
ASSOCIATED COLD FRONT WEAKENS AS IT APPROACHES OUR SE GA COUNTIES
MON EVNG. MODEL GUIDANCE SHOWS CHCS FOR MEASURABLE PCPN DIMINISH
MON NGT AS FRONT MOVES FURTHER SOUTH...WILL KEEP POPS AT SLIGHT
CHANCE. FRONT MOVES JUST S OF OUR FCST AREA THEN STALLS TUES AS
IT BECOMES MORE OF A WARM FRONT. MODEL GUIDANCE SUGGESTS BULK OF
RAIN CHANCES TUES ARE W OF FCST AREA...BUT WILL HAVE AT LEAST SLIGHT
CHANCE OVER SRN/WRN PART OF FCST AREA ON NORTH SIDE OF WARM FRONT.
RAIN FCST TO BREAK OUT N OF WARM FRONT IN ISENTROPIC LIFT TUE NGT...
HAVE LIKELY POPS ACRS SRN GA...40-50 POPS FAR NRN FL WITH 30 POPS
IN OUR SRNMOST COUNTIES. ANTICIPATE LOW TEMPS TUE NGT AROUND 06Z
WITH SLOWLY RISING TEMPS/DWPTS TWRD DAWN WED.
.LONG TERM...WED-SUN...ALL EYES FOCUSED ON WED/WED NGT EVENT. STORM
SYSTEM FCST BY MODELS TO DRIFT S AND E ACRS NRN MEXICO UNTIL STORM
SYSTEM OVER THE ERN PACIFIC MOVES INTO WRN CANADA ARND UPR RIDGE
THEN DIVES SWD TWRD NRN/CTRL PLAINS. THIS SYSTEM IS FCST TO
ENCOURAGE A FASTER EWD MOTION OF NRN MEXICO UPR LOW ACRS CTRL TX TUE
NGT AND LA/MS WED. BY WED NGT...MODELS OPEN UP UPR LOW AND
ACCELERATE NEG TILTED SYSTEM TWRD MID ATLANTIC STATES. ECMWF A
LITTLE SLOWER THAN GFS...BUT ALL GENERALLY POINT TO THIS SCENARIO.
GULF OF MEX MARINE BOUNDARY LAYER SLOWLY MODIFYING IN WAKE OF PRIOR
POLAR AIRMASS INTRUSION. MODEL GUIDANCE SUGGESTS 60KT LLJ WILL HELP
BRING L/M 60S DWPTS NWD TO GULF COASTLINE WED MORNING...POSSIBLY
ADVECTING ACRS FL PENINSULA AND SRN GA WED AFTN JUST AHEAD OF STRONG
COLD FRONT. GFS CONTINUES TO SHOW IMPRESSIVE DEEP UPWARD MOTION
ASSOCIATED WITH FRONTAL LIFT COUPLED WITH DIVERGENT RRQ OF UPR JET.
GFS BUFR SOUNDINGS INDICATE NARROW AXIS OF 500-1000 J/KG CAPE
POSSIBLE ALONG COLD FRONT...WITH IMPRESSIVE 400-600 HELICITY VALUES
ACRS WARM SECTOR. CLOSEST SIMILARITY IN RECENT PAST IS EVENT ON MAR
7 2008...WITH SIMILAR HIGH SHEAR/WEAK INSTABILITY ENVIRONMENT AND
STRONG UPR SYSTEM ALONG SIMILAR TRACK...RESULT WAS OVER 20 TORNADO
REPORTS ACRS NRN FL/SRN GA ASSOCIATED WITH LEWP SQUALL LINE. OF
COURSE...IF HIGHER DWPTS STAY OFFSHORE...WE MAY END UP WITH A SQUALL
LINE THAT WEAKENS AS IT MOVES WELL INLAND FROM GULF OF MEX. WILL
HAVE TO WATCH THIS CLOSELY...SEE IF SUFFICIENT INSTABILITY CAN DVLP
OR IF INTENSE LIFT CAN PARTIALLY MAKE UP FOR LACK OF BETTER
INSTABILITY.
FOR WED MRNG...ANTICIPATE MOST RAIN TO BE ACRS CTRL/SRN GA WITH WARM
FRONT...WITH SUBSIDENCE SHOWN ON GFS TO RESULT IN FAIRLY DRY WARM
SECTOR...POSSIBLY SOME BREAKS OF SUN DEPENDING ON AMOUNT OF HIGH
CLOUDS. TEMPS MAY GET INTO 75-80 RANGE ACRS FL PENINSULA. WED AFTN...
SQUALL LINE OVER ERN GULF OF MEX WILL START TO MOVE INLAND.
ANTICIPATE A RATHER FAST MOVING SQUALL LINE...WHICH GETS TO THE
COAST DURING THE EVNG. LIKELY POPS IN AFTN/EVNG ASSOCIATED WITH
SQUALL LINE. WILL MAINTAIN HIGHER POPS ERN/SRN ZONES WED NGT IN CASE
SQUALL LINE ARRIVES A LITTLE LATER THAN PRESENTLY ANTICIPATED. IF
DWPTS JUST AHEAD OF COLD FRONT CAN GET HIGH ENOUGH TO GENERATE 500
J/KG CAPE'S...SEVERE WEATHER WILL BE LIKELY, GIVEN STRONG SHEAR
PRODUCED BY 50-60KT LLJ.
HIGH PRES BUILDS IN LATE THU INTO WEEKEND BRINGING SHOT OF MUCH
COOLER AIR. LATEST MED RANGE GUIDANCE SUGGESTS TEMPERATURES A LITTLE
BELOW CURRENT FORECAST...HINTING AT POSSIBLE LIGHT FREEZE INLAND
SECTIONS SAT MRNG. FOR NOW WILL ONLY TREND MED RANGE TEMPS DOWN
SLIGHTLY GIVEN LATEST GUIDANCE...AND SEE WHAT SUBSEQUENT MODEL RUNS
SHOW.
&&
.AVIATION...VFR CONDITIONS WILL PREVAIL THROUGH MOST OF THE PERIOD.
COULD SEE SOME MVFR CONDITIONS DUE TO BR BEFORE SUNRISE MONDAY
MORNING...ESPECIALLY AT GNV AND VQQ. WILL ALSO SEE A GRADUAL
INCREASE IN HIGH CLOUDS THROUGH THE PERIOD.
&&
.MARINE...VARIABLE WINDS LESS THAN 10 KTS AND SEAS 2 FT OR LESS
CONTINUE OVER THE WATERS THIS AFTN. EXPECT WINDS WILL BECOME MORE
SSW LATER THIS EVENING AS RIDGE CENTER SHIFTS FARTHER OFFSHORE. SCEC
CONDITIONS ARE LIKELY TUE FOLLOWING WEAK FROPA AS THE PRESSURE
GRADIENT TIGHTENS IN ADVANCE OF APPROACHING GULF LOW. SCA CONDITIONS
POSSIBLE OFFSHORE TUE NIGHT...THEN HIGH CONFIDENCE WITH SCA LATE
WED-THU WITH POSSIBLE GALES OFFSHORE. CONDITIONS WILL GRADUALLY
IMPROVE FRI AS HIGH PRESSURE BUILDS EASTWARD FROM THE GULF COAST
REGION.
&&
.FIRE WX...ISSUED A LAST-MINUTE RED FLAG WARNING FOR ALL FL ZONES
LESS FLAGLER AND ST JOHNS AROUND 1130 EST BECAUSE DEW PTS HAD
CRASHED INTO THE UPPER 30S AT JAX. AFTER SOUNDING MODIFICATION
REALIZED THAT DEW PTS WERE MIXING DOWN FROM ABOUT 840 MB...AND WITH
STRONG LOW LEVEL SUBSIDENCE OVER THE AREA TODAY...SAW NO REASON WHY
MOST OF INLAND NE FL WOULD NOT MEET RED FLAG CONDITIONS THIS AFTN.
MOISTURE VALUES ARE PROGGED TO INCREASE TONIGHT AS SSW FLOW
DEVELOPS...SO NO RED FLAG CONDITIONS ARE EXPECTED TOMORROW NOR TUE.
&&
.PRELIMINARY POINT TEMPS/POPS...
AMG 44 73 46 65 / 0 10 20 10
SSI 51 72 52 65 / 0 0 10 10
JAX 45 74 51 67 / 0 0 10 20
SGJ 51 74 55 69 / 0 0 10 20
GNV 42 74 50 70 / 0 0 10 20
OCF 42 75 52 71 / 0 0 10 20
&&
.JAX WATCHES/WARNINGS/ADVISORIES...
FL...RED FLAG WARNING UNTIL 5 PM EST THIS AFTERNOON FOR
ALACHUA-BAKER-BRADFORD-CLAY-COLUMBIA-DUVAL-GILCHRIST-
HAMILTON-MARION-NASSAU-PUTNAM-SUWANNEE-UNION.
GA...NONE.
AM...NONE.
&&
$$
WOLF/ENYEDI/KEEGAN
