FXUS62 KJAX 151827 AFDJAX AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE JACKSONVILLE FL 127 PM EST SAT DEC 15 2007 ...HIGH RAIN CHANCES TONIGHT WITH A SLIGHT RISK OF SEVERE STORMS... .SHORT TERM...MSAS ANALYSIS INDICATES SURFACE WARM FRONT HAS LIFTED TO THE NORTHERN FRINGES OF JAX CWA (I.E. NEAR THE ALTAMAHA RIVER). DOPPLER RADARS SHOW SCATTERED SHOWERS OVER INLAND SOUTHEAST GEORGIA... WITH DRY CONDITIONS NOTED ELSEWHERE. CANNOT RULE OUT ISOLATED THUNDERSTORMS THIS AFTERNOON (AGAIN FOCUSING ALONG THE WARM FRONT). WARM AND HUMID CONDITIONS WILL BE THE NORM THE REMAINDER OF TODAY WITH TEMPS WARMING INTO THE 70S EXCEPT POCKETS OF LOWER 80S FROM GNV SOUTH TO OCF. BREEZY SOUTHERLY WINDS WILL ALSO ESTABLISH THIS AFTERNOON WITH WIND SPEEDS OF 10 TO 20 MPH. SEVERAL WEATHER EVENTS TO TALK ABOUT FOR THE SHORT-TERM. NUMERICAL MODELS ARE IN GENERAL AGREEMENT SHOWERS AND THUNDERSTORMS WILL BE ON THE INCREASE LATE THIS EVENING THROUGH TONIGHT. SHARP UPPER TROUGH WILL SWING FROM THE CENTRAL PLAINS TOWARDS THE MID-ATLANTIC/ SOUTHEAST REGIONS LATER TONIGHT...SENDING A STRONG COLD FRONT ACROSS THE LOCAL AREA. DEW-POINTS HAVE ALREADY RISEN INTO THE 60S...AND WILL LIKELY FURTHER RISE OVERNIGHT AS PLUME OF MOISTURE ASSOCIATED WITH REMNANTS OLGA IS SHUNTED NORTHWARD. THIS INCREASE OF MOISTURE/ INSTABILITY WILL INTERACT WITH FAVORABLE DYNAMICS ASSOCIATED WITH APPROACHING TROUGH AND ATTENDANT FRONTAL BOUNDARY TO GENERATE NUMEROUS TO WIDESPREAD SHOWERS AND THUNDERSTORMS. AT THIS TIME...APPEARS A LINE OF THUNDERSTORMS (POSSIBLY A SQUALL LINE) WILL ADVANCE TOWARDS THE EASTERN FLORIDA PANHANDLE LATE THIS AFTERNOON... REACHING PORTIONS OF INTERIOR SOUTHEAST GEORGIA AND MAINLY THE SUWANNEE VALLEY REGION OF NORTHEAST FLORIDA LATE THIS EVENING. THIS LINE OF THUNDERSTORMS WILL CONTINUE TO PROPAGATE EAST OVERNIGHT... REACHING THE COASTAL COUNTIES PRIOR TO DAYBREAK THEN CLEARING THE MAINLAND SUNDAY MORNING. AS MENTIONED IN EARLIER DISCUSSIONS...THE MAIN CONCERN WITH THESE THUNDERSTORMS WILL BE STRONG AND DAMAGING WINDS. NUMERICAL MODELS INDICATE 850 WINDS WILL INCREASE TO 60 KNOTS. OTHER CONCERNS INCLUDE: SMALL HAIL (MINIMAL GIVEN WARM TEMPS ALOFT)...ISOLATED TORNADOES/WATERSPOUTS DUE TO FAVORABLE DIRECTIONAL/SPEED SHEAR IN THE LOWER LEVELS OF THE ATMOSPHERE...AND HEAVY RAINFALL. SPC DAY 1 CONVECTIVE OUTLOOK INCLUDES THE ENTIRE JAX CWA UNDER SLIGHT RISK AREA. STRONG COLD FRONT WILL IMMEDIATELY FOLLOW THIS LINE OF THUNDERSTORMS...USHERING MUCH COLDER AND DRIER CONDITIONS THROUGH EARLY NEXT WEEK. GUSTY NORTHWEST WINDS AND CLEARING SKIES WILL ENSUE SUNDAY. SOME FORM OF WIND ADVISORY PRODUCT WILL BE NEEDED WITH THE BOSTON TECHNIQUE INDICATING WIND GUSTS EXCEEDING 30 MPH AT TIMES. COLD HIGH PRESSURE WILL LIKELY CENTER OVER THE UPPER TEXAS COAST/LOUISIANA SUNDAY NIGHT...WITH RIDGE AXIS EXTENDING EAST ACROSS THE BALANCE OF THE GULF COAST STATES. THE COMBINATION OF VERY DRY CONDITIONS...CLEAR SKIES AND WEAKENING WINDS WILL SET THE STAGE FOR PLUMMETING TEMPERATURES SUNDAY NIGHT. PROJECTED LOWS FOR SUNDAY NIGHT/MONDAY MORNING RANGE FROM THE UPPER 20S ACROSS OUR WESTERN-MOST ZONES TO MID 30S ALONG THE IMMEDIATE COASTLINE. WILL HOIST FREEZE WATCH FOR THE INTERIOR COUNTIES...AS WELL AS INLAND SECTIONS OF GLYNN...CAMDEN...NASSAU AND DUVAL COUNTIES. AT THIS TIME...FREEZING TEMPS ARE NOT FORECAST FOR THE INLAND SECTIONS OF ST. JOHNS AND FLAGLER COUNTIES. HOWEVER...THIS IS CERTAINLY SUBJECT TO CHANGE. DRY AND MUCH COLDER CONDITIONS ARE FORECAST THROUGH TUESDAY...WITH ANOTHER FREEZE EVENT FOR MOST OF THE AREA MONDAY NIGHT. A FREEZE WATCH FOR THIS EVENT WILL BE ISSUED EITHER BY THE MIDNIGHT SHIFT OR THE SUNDAY DAY SHIFT. .LONG TERM (WED THROUGH SAT)...PROGRESSIVE PATTERN IS FORECAST LATE NEXT WEEK. COLDEST TEMPS ARE FORECAST WEDNESDAY MORNING AS COLD HIGH PRESSURE ADVANCES ACROSS THE LOCAL AREA. FREEZING/NEAR FREEZING TEMPS WILL BE COMMON NORTH OF U.S. HIGHWAY 82. HIGH PRESSURE WILL WEAKEN WHILE SHIFTING EAST-NORTHEAST OF THE AREA WEDNESDAY. AN ONSHORE FLOW WILL ESTABLISH OVER THE COASTAL SECTIONS...ALONG WITH MODERATION OF TEMPS. DRY CONDITIONS WILL LINGER THROUGH WEDNESDAY. ANOTHER COLD FRONT IS FORECAST TO ADVANCE ACROSS THE AREA THURSDAY. ALTHOUGH DYNAMICS APPEAR IMPRESSIVE...MOISTURE WILL BE A LIMITING FACTOR. THUS...WILL BE MAINTAIN LOW-END POPS. && .AVIATION...WITH WARM FRONT LIFTING NORTH OF THE AREA...MOST SITES HAVE BROKEN OUT NICELY WITH VFR TO OCCASIONAL MVFR BEING REPORTED. WITH INCREASING INSTABILITY BY 22Z...SHRA SHOULD BE ON THE INCREASE ACCORDING TO MODEL GUIDANCE ALTHOUGH A FOCUS FOR THE CONVECTION WILL BE LIMITED INITIALLY. STILL EXPECT CLOUD DECK TO FILL IN ONCE AGAIN WITH MVFR CONDITIONS IN TEMPO SHRA THROUGH 02Z. AFTER WHICH...MAIN FRONTAL BAND WILL APPROACH THE REGION AND DESPITE IMPRESSIVE DYNAMICS...BEST CAPE PROFILES ARE MARGINALLY SUPPORTIVE OF TS. FOR NOW...WILL KEEP WORDING AS VCTS IN PREDOMINANT SHRA...BUT THIS WILL NEED TO BE RE-VISITED AS FRONT APPROACHES. HAVE GONE WITH THE GFS MOS FOR NOW FOR THE QUICKER CLEAROUT ALTHOUGH HAVE BLENDED SOME ELEMENTS OF THE MET AS WELL. THIS SHOULD RESULT IN CLEARING OUT AFT 15Z WITH STRONG GUSTY WINDS FOR THE AFT HOURS AT ALL TERMINAL SITES. && .MARINE...WINDS MAINTAINING THEMSELVES IN THE SCEC RANGE IN WARM SECTOR AND THIS SHOULD CONTINUE INTO THE LATE AFTERNOON HOURS. WIND INCREASE WILL THEN COMMENCE WITH SCA FOR THE OFFSHORE PORTION...EXPANDING TO THE NEARSHORE POTION BY 06Z. MODELS AGREE ON A SMALL ARE OVER THE OFFSHORE PORTION THAT COULD REACH GALE STRENGTH BY SUN MORNING. FOR NOW...WILL GO WITH OCCASIONAL GUSTS TO GALE FORCE AND LEAVE ANY GALE WARNINGS FOR LATER SHIFTS. STRONG COLD AIR ADVECTION PATTERN CONTINUES INTO MON WITH CONTINUED SCA FLAGS FOR THE WATERS. HIGH PRESSURE WILL THEN BUILD NORTH OF THE WEST OF THE REGION WITH A GRADUAL REDUCTION IN WINDS AND SEAS. && .FIRE WEATHER...COLD FRONT TO MOVE THROUGH TONIGHT FOLLOWED BY MUCH DRIER AND COLDER AIR FOR THE REGION. SUNDAY LOOKS TO BE A CLOSE CALL OVER THE SUWANNEE VALLEY AS DECREASING DEWPOINTS AND INCREASING WINDS LEAD TO A SMALL WINDOW FOR RED FLAGS TO BE REALIZED. AT THIS TIME...WITH THE MET GUIDANCE MUCH LESS DRY...WILL NOT ISSUE ANY WATCHES. THIS WILL NEED TO BE MONITORED CLOSELY HOWEVER...FOR IF FRONT MAKES IT THROUGH FASTER THAN EXPECTED...RED FLAG CONDITIONS COULD BE WIDESPREAD OVER FLORIDA PORTION WHEN WINDS ARE TAKEN INTO ACCOUNT. MON LOOKS TO BE MORE CLEAR CUT AND WILL ISSUE FIRE WEATHER WATCH FOR ENTIRE AREA WHICH WILL NEED TO BE UPGRADED WITH SUBSEQUENT PACKAGES. && .PRELIMINARY POINT TEMPS/POPS... AMG 52 57 28 55 / 90 10 0 0 SSI 59 63 35 53 / 90 30 0 0 JAX 60 62 30 54 / 80 40 0 0 SGJ 65 65 36 55 / 80 40 0 0 GNV 61 63 30 56 / 80 40 0 0 OCF 64 65 31 57 / 80 40 0 0 && .JAX WATCHES/WARNINGS/ADVISORIES... FL...FREEZE WATCH FROM LATE SUNDAY NIGHT THROUGH MONDAY MORNING FOR ALACHUA-BAKER-BRADFORD-COLUMBIA-GILCHRIST-HAMILTON-MARION- SUWANNEE-UNION. FREEZE WATCH FROM LATE SUNDAY NIGHT THROUGH MONDAY MORNING FOR CLAY-DUVAL-NASSAU-PUTNAM. FIRE WEATHER WATCH FROM MONDAY MORNING THROUGH MONDAY AFTERNOON FOR ALACHUA-BAKER-BRADFORD-CLAY-COLUMBIA-DUVAL-FLAGLER- GILCHRIST-HAMILTON-MARION-NASSAU-PUTNAM-ST JOHNS-SUWANNEE- UNION. GA...FREEZE WATCH FROM LATE SUNDAY NIGHT THROUGH MONDAY MORNING FOR APPLING-ATKINSON-BACON-BRANTLEY-CHARLTON-CLINCH-COFFEE- ECHOLS-JEFF DAVIS-PIERCE-WARE-WAYNE. FIRE WEATHER WATCH MONDAY AFTERNOON FOR APPLING-ATKINSON-BACON- BRANTLEY-CHARLTON-CLINCH-COASTAL CAMDEN-COASTAL GLYNN- COFFEE-ECHOLS-INLAND CAMDEN-INLAND GLYNN-JEFF DAVIS-PIERCE- WARE-WAYNE. FREEZE WATCH FROM LATE SUNDAY NIGHT THROUGH MONDAY MORNING FOR INLAND CAMDEN-INLAND GLYNN. AM...SMALL CRAFT ADVISORY FROM 6 PM THIS EVENING TO 7 PM EST MONDAY FOR ST AUGUSTINE TO FLAGLER BEACH FL 20 NM TO 60 NM OFFSHORE. SMALL CRAFT ADVISORY FROM 6 PM THIS EVENING TO 12 PM EST MONDAY 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. SMALL CRAFT ADVISORY FROM MIDNIGHT TONIGHT TO 8 AM EST MONDAY 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/DEESE/WALKER