Severe Thunderstorm Warning 191, NWS Jacksonville, FL

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE JACKSONVILLE FL
400 AM EST MON DEC 25 2006

...SLIGHT RISK OF SEVERE STORMS TODAY...

.SYNOPSIS...WATER VAPOR IMAGERY SHOWING UPPER TROUGH FROM THE PLAINS
TO MEXICO WITH AN UPPER LOW ROUNDING BASE OF TROUGH ACROSS EASTERN
TEXAS. SURFACE ANALYSIS SHOWING DEEPENING SFC LOW (1002MB) ACROSS
EXTREME SW MISSISSIPPI. WARM FRONT EXTENDS SE OF THE LOW ACROSS
THE FL PANHANDLE AND EXTREME N FL WHILE THE TRAILING COLD FRONT
IS SOUTH OF THE WESTERN PANHANDLE OVER THE GULF. SATELLITE AND
RADAR CONTINUES TO SHOW A DEVELOPING SQUALL LINE ACROSS
THE NE GULF...OUT AHEAD OF THE FRONT...BEGINNING TO MOVE NE. THE
STRONGEST STORMS CONTINUE TO BE ACROSS THE CENTRAL NE GULF. A LARGE
AREA OF SHOWERS WITH EMBEDDED STORMS COVERS MUCH OF NORTH FL AND
THE GULF. A FEW OF THE STORMS ACROSS GA HAVE HAD SOME ROTATION
BUT HAVE NOT PRODUCED ANY SEVERE WX OVERNITE.

.SHORT TERM (TODAY-WED)...CONSENSUS OF THE MODELS IS THAT THE
SURFACE LOW WILL TRACK TO THE NE TODAY AND DEEPEN TO AROUND
1000 MB BEFORE REACHING THE TENN AND OHIO VALLEY THIS EVE.
THIS WILL DRIVE THE WARM FRONT NORTH OF THE CWA THIS AM AND
THE COLD FRONT INTO SE GA LATE THIS AFTERNOON AND NE FL THIS
EVE. STRONG DIVERGENCE ALOFT COUPLED WITH LOW LEVEL CONVERGENCE WILL
LEAD TO A PRE-FRONTAL SQUALL LINE MOVING THROUGH OUR WESTERN CWA
THIS MORNING AND SOUTHEAST CWA THIS AFTERNOON AND EVE. AS FOR SEVERE
POTENTIAL...SPC DOES HAVE MUCH OF THE AREA UNDER A SLIGHT RISK AND
THIS APPEARS VERY REASONABLE. THE JET DYNAMICS ARE FAVORABLE (50 TO
60 KNOT LOW LEVEL JET WITH DIVERGENCE ALOFT) AND THE DEEP LAYER
SHEAR SUPPORTS ORGANIZED ROTATING UPDRAFTS. HOWEVER...THE INSTABILITY
WILL BE LIMITED AS A RESULT OF THE WIDESPREAD PCP OUT AHEAD OF THE
LINE AND THIS WILL HELP SUPPRESS SUPERCELL DEVELOPMENT (REFER TO
SWODY1). ITS VERY POSSIBLE THAT IF SOME AREAS CAN GET SOME
HEATING GOING THIS AFTERNOON (WHICH WILL BE MOST LIKELY IN THE SE)
WE COULD GET SOME SEVERE STORMS GOING THERE WHERE THE MAIN CONCERNS
WOULD BE DAMAGING WINDS. WILL HIGHLITE THIS IN HWO. EXPECT THS LINE
OF STORMS TO PUSH EAST OF THE AREA DURING THE EVENING. COOLER AND
DRIER AIR WILL FILTER IN TONIGHT BEHIND THE FRONT...HOWEVER WITH THE
UPPER LOW STILL TO THE WEST...COLD AIR ADVECTION WILL NOT BE THAT
GREAT AND EXPECT MIN TEMPS TUES AM TO BE IN THE UPPER 40S TO LOW
50S. TUESDAY...A CHILLY DAY TUE WITH CLOUDY SKIES TO START AND A
TIGHT PRESSURE GRADIENT OVER THE AREA MAKING FOR A BREEZY DAY. SKIES
BEGIN TO BECOME PARTLY CLOUDY TUE AFTN ONCE THE 850 MB TROUGH PUSHES
DOWNSTREAM AND DRIER AIR FILTERS INTO FROM THE NW. TUE NIGHT AND
WED...CLEAR/SUNNY SKIES BOTH DAYS AS RIDGING BUILDS IN FROM THE GULF
COAST REGION. A COOL START TO WED AS MINS NEAR FREEZING ACROSS THE
INTERIOR WITH A REBOUND ONLY INTO THE UPPER 50S AND LOW 60S.

&&

.AVIATION...CONDITIONS DETERIORATING AS RAIN SPREADS NE FROM THE
GULF. EXPECTING MAINLY IFR CONDITIONS FROM LOW CEILINGS WITH
PERIODS OF MVRF. SOUTHERLY LOW LEVEL JET COUPLED WITH MUCH LIGHTER
WINDS AT THE SURFACE PRODUCING LOW LEVEL WIND SHEAR UNTIL AROUND
12Z. EXPECTING A PRE-FRONTAL SQUALL LINE TO PUSH THROUGH THE AREA
EARLY THIS AFTERNOON (16-20Z) AND MAY PRODUCE WIND GUSTS TO
35 KNOTS. CONDITIONS GRADUALLY IMPROVING LATER IN THE AFTERNOON
AND EVE AS THE PRE-FRONTAL TROUGH/SQUALL LINE MOVES THROUGH BUT
DO EXPECT MVFR INTO THE EARLY EVE.

&&

.MARINE...SMALL CRAFT ADVISORY IN EFFECT. WARM FRONT LIFTS NORTH
OF THE WATERS THIS MORNING AND PRE-FRONTAL TROUGH WITH ASSOCIATED
SQUALL LINE WILL MOVE THROUGH THIS AFTERNOON. WINDS ARE ALREADY AT
SCA CRITERIA JUST TO THE SOUTH AND EXPECT THE WINDS TO VEER MORE
AND INCREASE THIS MORNING. MAIN CONCERN WILL BE THIS AFTERNOON
AS WE MAY SEE STRONGER WINDS/HIGHER SEAS IN AND NEAR THUNDERSTORMS.
COLD FRONT PUSHES THROUGH THE WATERS TONIGHT WITH WINDS SHIFTING
TO WEST AND INCREASING. MAY NEED A GALE WARNING BUT WILL CONTINUE
WITH CURRENT ADVISORY WITH MENTION OF GUSTS TO GALE FORCE.

&&

.PRELIMINARY POINT TEMPS/POPS...
AMG  68  48  54  33 / 100  10   0   0
SSI  70  52  58  38 /  90  20  10   0
JAX  73  52  59  35 /  90  30  10   0
SGJ  76  56  63  40 /  90  60  10   0
GNV  73  53  60  34 /  90  30  10   0
OCF  74  55  62  35 /  90  50  10   0

&&

.JAX WATCHES/WARNINGS/ADVISORIES...
FL...NONE.
GA...NONE.
AM...SMALL CRAFT ADVISORY UNTIL 10 PM EST TUESDAY 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 10 PM EST TUESDAY 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.

&&

PP/PW

HAZARDOUS WEATHER OUTLOOK...UPDATED
NATIONAL WEATHER SERVICE JACKSONVILLE FL
630 AM EST MON DEC 25 2006

FLZ020>025-030>033-035>038-040-GAZ132>136-149>154-162>166-261100-
HAMILTON-SUWANNEE-COLUMBIA-BAKER-NASSAU-DUVAL-UNION-BRADFORD-CLAY-
ST JOHNS-GILCHRIST-ALACHUA-PUTNAM-FLAGLER-MARION-COFFEE-
JEFF DAVIS-BACON-APPLING-WAYNE-ATKINSON-WARE-PIERCE-BRANTLEY-
INLAND GLYNN-COASTAL GLYNN-ECHOLS-CLINCH-CHARLTON-INLAND CAMDEN-
COASTAL CAMDEN-
630 AM EST MON DEC 25 2006

THIS OUTLOOK IS FOR NORTHEAST FLORIDA AND SOUTHEAST GEORGIA.

.DAY ONE...TODAY AND TONIGHT...

...TORNADO WATCH IN EFFECT UNTIL 1 PM EST ...

A TORNADO WATCH IS IN EFFECT FOR MUCH OF THE REGION UNTIL
1 PM EST THIS AFTERNOON. FOR MORE INFORMATION ON WHAT
COUNTIES ARE IN THE WATCH...REFER TO THE WATCH COUNTY
NOTIFICATION MESSAGE.

A SQUALL LINE DEVELOPING ACROSS THE EASTERN GULF WILL MOVE
ACROSS THE REGION LATE THIS MORNING AND AFTERNOON. THE AIRMASS
MAY DESTABILIZE ENOUGH RESULTING IN SOME OF THE STORMS ALONG THE
LINE TO BECOME SEVERE. THE MAIN CONCERNS WILL BE FOR TORNADOES...
DAMAGING WIND GUSTS...AND POSSIBLE HAIL.

.DAYS TWO THROUGH SEVEN...TUESDAY THROUGH SATURDAY...
THE NEXT COLD FRONT IS EXPECTED TO APPROACH THE AREA SATURDAY
BRINGING WITH IT A CHANCE OF THUNDERSTORMS.

.SPOTTER INFORMATION STATEMENT...

SPOTTER ACTIVATION MAY BE NEEDED LATE THIS MORNING AND AFTERNOON.

FOR ADDITIONAL INFORMATION...VISIT THE NATIONAL WEATHER SERVICE
IN JACKSONVILLE WEBSITE ON THE INTERNET AT WWW.SRH.NOAA.GOV/JAX.

PP