Red Flag Warning 33, NWS Jacksonville, FL

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE JACKSONVILLE FL
240 PM EDT WED MAR 19 2008

.SHORT TERM...CONVECTION IS STRUGGLING ACROSS THE REGION WITH
LIGHTNING STRIKES LIMITED TO SOUTH CAROLINA. IN FACT...SATELLITE
IMAGERY IS SHOWING WARMING CLOUD TOPS. FULL LATITUDE TROUGH
IS ADVANCING TOWARDS THE EASTERN UNITED STATES WITH ATTENDANT
SURFACE LOWS PHASING OVER THE MID-TENNESSEE VALLEY REGION...WITH
TRAILING COLD FRONT ADVANCING OVER THE WESTERN FLORIDA PANHANDLE.

WINDY CONDITIONS WILL CONTINUE TO AFFECT THE AREA THE REMAINDER
OF TODAY ALTHOUGH WIND SPEEDS ARE SUSTAINING BETWEEN 15 AND 20 MPH
WITH GUSTS TO 30 MPH (MORE LAKE WIND ADVISORY CRITERIA). WITH
SEVERAL HOURS REMOVED FROM SUNSET..THERE IS STILL THE POTENTIAL
FOR SLIGHTLY STRONGER WINDS TO MIX TO THE SURFACE. THUS...WILL
MAINTAIN WIND ADVISORY FOR AREA COUNTIES. PRE-FRONTAL SHOWERS ARE
FORECAST TO INITIATE ACROSS OUR WESTERN-MOST ZONES LATE THIS
AFTERNOON...WITH BULK OF ACTIVITY HOLDING OFF UNTIL THE LATE
EVENING AND OVERNIGHT.

MAIN FORECAST CHALLENGE THROUGH THE SHORT-TERM WILL BE THUNDERSTORM
ACTIVITY TONIGHT. BRUNT OF ENERGY ASSOCIATED WITH APPROACHING TROUGH
WILL HOLD WELL TO THE NORTH. A DEEP LAYER SOUTHWEST FLOW REGIME
WILL ATTEMPT TO PROVIDE A LID ON DEVELOPMENT UNTIL MAIN TROUGH
AXIS APPROACHES. MSAS ANALYSIS INDICATE TAMED DEW-POINTS IN THE
LOWER 60S COMPLIMENTS OF SOUTHERLY TRAJECTORY OVER THE FLORIDA
PENINSULA. DEW-POINTS IN THE UPPER 60S AND LOWER 70S WERE NOTED
OVER THE NORTHEAST GULF OF MEXICO.

AS FRONTAL SYSTEM NEARS FROM THE WEST...LOW-LEVEL FLOW WILL
ACQUIRE A SOUTHWEST COMPONENT. THIS FLOW REGIME SHOULD BRING
INFLUX OF MOISTURE AND INSTABILITY FROM THE GULF OF MEXICO. THIS
COUPLED WITH FAVORABLE DYNAMICS SUPPORT SHOULD TRIGGER BANDS OF
SHOWERS WITH EMBEDDED THUNDERSTORM ACTIVITY. WILL CONTINUE TO
ADDRESS LIKELY POPS. MAIN CONCERN WITH ANY THUNDERSTORM
DEVELOPMENT WILL BE STRONG WINDS AS LOW-LEVEL JET CONTINUES TO
ALIGN OVER THE AREA.

FRONT WILL LIKELY CLEAR THE AREA OVERNIGHT WITH SHOWER DEVELOPMENT
LIMITED TO EXTREME SOUTHEAST PORTIONS OF JAX CWA DURING THE EARLY
MORNING. HIGH PRESSURE IS THEN FORECAST TO ADVANCE ACROSS THE
AREA THROUGH FRIDAY NIGHT...ACCOMPANIED BY DRY AND COOLER
CONDITIONS.

THERE IS UNCERTAINTY WITH THE FORECAST FOR SATURDAY. IT APPEARS
OLD FRONTAL BOUNDARY WELL TO THE SOUTH WILL ATTEMPT TO LIFT NORTH
WITH A SURFACE WAVE ADVANCING ALONG THIS FEATURE. AT THIS TIME...
SURFACE WAVE WILL LIKELY ADVANCE ACROSS CENTRAL FLORIDA ALONG
WITH STRONGEST DYNAMICS. HAVE LIMITED POPS FOR AREAS MAINLY SOUTH
OF A GAINESVILLE TO ST. AUGUSTINE LINE...BUT THIS WILL BE SUBJECT
TO CHANGE.

.LONG TERM...USING ENSEMBLE GFS...A WEAK COLD FRONT IS FORECAST TO
CLEAR THE AREA SATURDAY EVENING WITH ATTENDANT SHOWERS OVER MAINLY
THE COASTAL WATERS. HIGH PRESSURE SYSTEM WILL THEN DOMINATE THE
AREA THROUGH SUNDAY...PROVIDING DRY AND STABLE CONDITIONS.
SCATTERED SHOWERS ARE FORECAST SUNDAY NIGHT WITH ARRIVAL OF FAIRLY
VIGOROUS SHORTWAVE TROUGH AND POSSIBLE SURFACE REFLECTION. IF
CONFIDENCE INCREASES OF THIS SCENARIO...HIGHER POPS WILL BE
NEEDED. SHORTWAVE TROUGH AND RELATED DYNAMICS WILL LIKELY CLEAR
THE AREA EARLY MONDAY...WITH DRY HIGH PRESSURE RE-ESTABLISHING
OVER THE AREA FOR MUCH OF NEXT WEEK.

&&

.AVIATION...MVFR CONDITIONS DUE TO LOW CIGS ARE EXPECTED THIS
EVENING AS LOW LEVEL CLOUDINESS INCREASES FROM THE W IN ADVANCE OF
APPROACHING COLD FRONT. HAVE INCLUDED WIND SHEAR IN THE TAFS TONIGHT
DUE TO STRONG LOW LEVEL SSW JET OF 40-50 KTS AROUND 3-4KFT. FRONT
WILL BE PRECEDED BY A THIN LINE OF MOD-HVY RA WITH A FEW EMBEDDED TS
POSSIBLE...BUT INSTABILITY LACKING SO NOT HIGH ENOUGH CONFIDENCE TO
INCLUDED TS IN TEMPO GROUPS AT THIS TIME. FROPA WILL OCCUR BEFORE
SUNRISE THU WITH WINDS SHIFTING TO THE NNW.

&&

.MARINE...WILL CONTINUE WITH SCA FOR ALL LEGS TONIGHT WITH MENTION
OF OCCASIONAL GUSTS TO GALE FORCE OFFSHORE IN LIEU OF A GALE
WARNING. WINDS/SEAS WILL SUBSIDE LATE THU/THU NIGHT. LOW PRESSURE
FORECAST TO DEVELOP S OF THE WATERS THIS WEEKEND MAY INCREASE THE
LOCAL PGRAD ENOUGH FOR A RETURN TO SCA CONDITIONS SUN.

&&

.FIRE WEATHER...UPGRADED THE WATCH FOR THU AFTN TO A RED FLAG
WARNING TO ALL OF OUR INLAND N FL ZONES DUE TO EXTENDED DURATIONS OF
LOW RHS. A FIRE WX WATCH MAY BE NEEDED FOR OUR INLAND N FL ZONES FRI
AFTN DUE TO LOW RHS...BUT ENOUGH LOW LEVEL ATLANTIC MOISTURE MAY
ADVECT INLAND TO PREVENT EXTENDED DURATIONS OF CRITICAL RH VALUES.

&&

.PRELIMINARY POINT TEMPS/POPS...
AMG  80  52  70  40 /  30  70   0   0
SSI  76  58  66  48 /  10  70   0   0
JAX  84  59  68  46 /  10  70   0   0
SGJ  82  61  68  52 /   0  60  10   0
GNV  84  59  73  44 /  10  70   0   0
OCF  85  61  74  45 /   0  60  10   0

&&

.JAX WATCHES/WARNINGS/ADVISORIES...
FL...WIND ADVISORY UNTIL 8 PM EDT THIS EVENING FOR ALACHUA-BAKER-
     BRADFORD-CLAY-COLUMBIA-DUVAL-FLAGLER-GILCHRIST-HAMILTON-
     MARION-NASSAU-PUTNAM-ST JOHNS-SUWANNEE-UNION.

     RED FLAG WARNING FROM 12 PM TO 8 PM EDT THURSDAY FOR ALACHUA-
     BAKER-BRADFORD-CLAY-COLUMBIA-DUVAL-GILCHRIST-HAMILTON-
     MARION-NASSAU-PUTNAM-SUWANNEE-UNION.

GA...WIND ADVISORY UNTIL 8 PM EDT THIS EVENING FOR APPLING-ATKINSON-
     BACON-BRANTLEY-CHARLTON-CLINCH-COASTAL CAMDEN-COASTAL GLYNN-
     COFFEE-ECHOLS-INLAND CAMDEN-INLAND GLYNN-JEFF DAVIS-PIERCE-
     WARE-WAYNE.

AM...SMALL CRAFT ADVISORY UNTIL 4 PM EDT THURSDAY 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.

     SMALL CRAFT ADVISORY UNTIL 6 AM EDT THURSDAY FOR ALTAMAHA SOUND
     GA TO FERNANDINA BEACH FL OUT 20 NM-FERNANDINA BEACH TO ST
     AUGUSTINE FL OUT 20 NM-ST AUGUSTINE TO FLAGLER BEACH FL OUT
     20 NM.

&&

ZAPPE/ENYEDI/KEEGAN