910 FXUS62 KTAE 201328 AFDTAE AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE TALLAHASSEE FL 920 AM EDT SAT MAR 20 2010 .SYNOPSIS... AT 9 AM...IT WAS SUNNY ACROSS THE SE REGION WITH SOME LOCATIONS STILL SHOWING LIGHT FOG. TEMPS RANGED FROM THE MID 40S NORTH TO LOW 50S AT THE COAST. WINDS WERE GENERALLY CALM. AT UPPER LEVELS... THE LARGE SCALE CONUS PATTERN IS HIGHLIGHTED BY A RIDGE OVER WRN CONUS...A TROUGH FROM HUDSON BAY DIGGING SWWD DOWN ROCKIES INTO THE TX PANHANDLE...AND A DEEP LAYER RIDGE OVER THE SOUTHEAST COAST. LOOKING SOUTH...WEAK RIDGING WAS NOTED OVER GULF WATERS WITH A SUBTROPICAL JET WAS STREAMING FROM MEXICO TO FL. DURING THE NEXT 12 HRS...SEVERAL SHORTWAVES/VORT MAXES WILL PHASE LATER TODAY IN OK/TX LEADING TO AN EVOLVING AND DEEPENING CLOSED LOW AT BASE OF TROUGH. THIS SYSTEM WILL MOVE SEWD TO RED RIVER VALLEY AND THEN DEEPEN OVER TX OVERNIGHT. IT WILL THEN MOVE TO OVER THE LOWER MS VALLEY SUNDAY MORNING AND EVOLVE INTO A CUTOFF LOW OVER NRN AL/SRN TN BY SUNRISE MON BEFORE MOVING TO SRN APPALACHIANS AND CNTRL NC BY MON EVE. ALL THIS WILL PUSH THE ERN RIDGE INTO THE ATLC BEGINNING LATER TODAY. THE CUTOFF LOW WILL MOVE OUT INTO THE ATLANTIC OCEAN BY WEDNESDAY WITH SOME RIDGING BUILDING OVER FLORIDA DURING MIDWEEK. AT LOWER LEVELS... ANALYSIS SHOWED HIGH PRESSURE ALONG THE CANADIAN/U.S.BORDER FROM THE PACIFIC TO THE UPPER GREAT LAKES AND A RIDGE EXTENDING FROM NORTH FL ALONG THE GULF COAST TO EAST TX. IN BETWEEN...A COLD FRONT FROM DEVELOPING LOW IN W/CNTRL TX NEWD THRU SRN OK...CENTRAL MO TO SECOND LOW IN QUEBEC. AS ABOVE UPPER TROUGH SWINGS EWD AND DEEPENS...TX LOW DEVELOPS AND MOVES NEWD AND ALSO DEEPENS CONSIDERABLY OVER AR LATER TODAY. IT THEN OCCLUDES OVER THE LOWER MS AND TN VALLEYS SWD INTO GULF ON SUNDAY AND THEN MOVE EWD TO NC ON MONDAY. THIS MOVEMENT WILL SURGE FRONT SEWD OVER TX AND NW GULF THRU TONIGHT...REACHING WRN FL PANHANDLE BY DAYLIGHT SUNDAY AND THEN TO THE FL PENINSULA SUNDAY EVENING. HIGH PRESSURE WILL BUILD IN FROM THE WEST ON MONDAY AND THEN MOVE ACROSS THE REGION THRU WEDNESDAY BEFORE MOVING OUT INTO THE ATLANTIC. ALL THIS REFLECTED IN MODEL SOUNDINGS. I.E. TAE GFS WITH 0.59 INCH PWAT AT 18Z SAT INCREASING TO 1.30 INCH PWAT AT 12Z SUN DROPPING TO 0.43 INCH PWAT BY 00Z MON. && .SHORT TERM...(THIS AFTERNOON THROUGH EARLY SUNDAY) THIS AFTERNOON...VERY PLEASANT AFTERNOON IN STORE FOR FIRST DAY OF SPRING WHICH OFFICIALLY BEGINS AT 132 PM EDT. WITH MOSTLY SUNNY SKIES TEMPERATURES WILL BE NEAR AVERAGE...MID 70S INLAND AND MID TO UPPER 60S AT THE COAST WHERE ONSHORE FLOW OFF THE COOL GULF WATERS WILL HAVE A SLIGHT COOLING EFFECT. TONIGHT...THE COLD FRONT WILL APPROACH LOCAL AREA OVERNIGHT. RAIN WILL BEGIN BY MIDNIGHT AND SLOWLY SPREAD EWD WITH 60-0% W-E POP GRADIENT. SUNDAY... THE FRONTAL RAIN BAND EXPECTED TO REACH THE FL PANHANDLE AND SOUTHEAST AL AROUND DAWN...THE TALLAHASSEE AND ALBANY AREAS BY EARLY TO MID AFTERNOON... THEN EXIT EAST OF OUR FORECAST AREA SUNDAY NIGHT. AS THE PARENT LOW OF THIS SYSTEM WILL BE STRONG AND LARGE... STRONG WIND FIELDS ARE EXPECTED. HOWEVER...SEVERE WX IS UNLIKELY AS THE BOUNDARY LAYER WINDS AHEAD OF THE FRONT WILL BE OUT OF THE SE FOR MOST OF THE PERIOD LEADING UP TO THE FRONTAL PASSAGE. THE OCCLUSION PROCESS WILL LIMIT NWD EXTENT OF RICHER LOW-LEVEL MOISTURE RETURN. THIS MAKES IT MORE DIFFICULT TO MODIFY THE CURRENTLY DRY/STABLE BOUNDARY LAYER...AS THE AIR WILL BE PASSING OVER THE DRY FL PENINSULA AND RELATIVELY COOL WATERS OF THE EASTERN GULF. NONE OF THE GUIDANCE SHOWS ANY SIGNIFICANT SBCAPE OR SURFACE DEWPOINTS EXCEEDING 60 DEGREES OVER OUR AREA...SO WE DO NOT THINK THAT AN ORGANIZED SEVERE WEATHER EVENT WILL OCCUR. MODELS INDICATE THAT THE MOST UNSTABLE AIR WILL REMAIN OFFSHORE OVER THE GULF OF MEXICO...AND THAT IS WHERE THUNDERSTORM ACTIVITY WILL BE GREATEST. FARTHER NORTH/INLAND...SFC DEWPOINTS ONLY LOW ENOUGH TO LIMIT THUNDERSTORM ACTIVITY... HOWEVER...WITH THE LOW-LEVEL JET IN PLACE OVER THE SERN STATES DURING THE DAY AND SUCH A STRONG WIND FIELD...ONE CAN NOT COMPLETELY RULE OUT AN ISOLATED DAMAGING WIND GUSTS. THE BEST CHANCE OF STRONG TO POSSIBLY SEVERE STORMS WILL BE NEAR THE COAST AND THE ADJACENT WATERS. BREEZY SOUTHWESTERLY WINDS ARE EXPECTED AND THERE IS THE POTENTIAL FOR STRONG WIND GUSTS EVEN OUTSIDE OF SHOWERS/STORMS. A WIND ADVISORY MAY BE REQUIRED FOR PORTIONS OF THE AREA. THIS SYSTEM IS FORECAST TO MOVE FAST ENOUGH AND WEAKEN SOMEWHAT SO THAT WIDESPREAD FLOODING IS NOT EXPECTED. STORM TOTAL RAINFALL AMOUNTS WILL GENERALLY BE AN INCH OR LESS. MONDAY... THERE WILL PROBABLY BE ENOUGH RESIDUAL DEEP LAYER MOISTURE AND WEAK VERTICAL MOTION TO SUPPORT A SLIGHT CHANCE FOR LIGHT SHOWERS. THE COMBINATION OF MOSTLY CLOUDY SKIES WRAPPING AROUND LOW ...GUSTY WINDS...AND HIGHS ONLY IN THE UPPER 50S TO MID 60S WILL MAKE THIS DAY FEEL A LOT MORE LIKE WINTER THAN SPRING. && .AVIATION...VFR CONDITIONS WILL PREVAIL THROUGH THE FORECAST PERIOD. SOUTHEAST WINDS 5 TO 7 KNOTS IN THE MORNING WILL VEER TO SOUTHERLY AROUND 10 KNOTS...ENHANCED BY A SEABREEZE THAT WILL DEVELOP AND PUSH INLAND DUE TO STRONG DAYTIME HEATING. SCATTERED CU WILL DEVELOP BY AFTERNOON...AND BY LATE AFTERNOON SCATTERED MID LEVEL CLOUDS WILL BEGIN TO SPREAD EASTWARD ACROSS THE AREA...UNDER A THICKENING LAYER OF HIGH CLOUDS. LOOKING AHEAD...A COLD FRONT WILL SWEEP EASTWARD ACROSS THE AREA ON SUNDAY...BRINGING WITH IT A BAND OF SHOWERS AND GUSTY SHIFTING WINDS. && .MARINE... LOW WINDS AND SEAS WILL RAPIDLY INCREASE TONIGHT AND SUNDAY WITH THE APPROACHING COLD FRONT. ADVISORY CONDITIONS APPEAR LIKELY LATER TONIGHT AND SUNDAY...AND THESE CONDITIONS WILL PERSIST AT LEAST THROUGH MONDAY AS THE SOUTHEAST U.S. WILL BE DOMINATED BY A LARGE...STRONG...OCCLUDED LOW MOVING VERY SLOWLY NORTHEAST. OUR WIND AND WAVE FORECAST IS BASED ON THE MEAN OF THE LATEST SUITE OF GUIDANCE...WHICH ENDS UP BEING A LITTLE LOWER THAN THE OPERATIONAL GFS/WNAWAVE RUN (WHICH ARE USUALLY TOO HIGH DURING THESE TYPES OF EVENTS). THE STRONG ONSHORE WINDS MAY CAUSE THE SURF ALONG THE FL PANHANDLE BEACHES TO APPROACH 7 TO 9 FT SUNDAY AND MONDAY...WHICH MAY REQUIRE A HIGH SURF ADVISORY. NUMEROUS RIP CURRENTS ARE ALSO LIKELY. THE EXTRATROPICAL STORM SURGE GUIDANCE (BASED ON THE 00 UTC GFS) FORECASTS TIDES OF 0.5 TO 1.5 FT ABOVE NORMAL DURING THE TIMES OF HIGH TIDE SUNDAY AFTERNOON AND EVENING...WITH THE HIGHEST VALUES MORE LIKELY ALONG THE EASTERN COAST OF APALACHEE BAY. SUCH VALUES ARE NOT USUALLY HIGH ENOUGH TO CAUSE WIDESPREAD FLOODING...BUT WE WILL MONITOR THESE TRENDS CLOSELY. && .TAE WATCHES/WARNINGS/ADVISORIES... AL...NONE. GA...NONE. FL...RED FLAG WARNING FROM 2 PM EDT /1 PM CDT/ THIS AFTERNOON TO 7 PM EDT /6 PM CDT/ THIS EVENING FOR THE FOLLOWING ZONES: BAY... CALHOUN...COASTAL WALTON...DIXIE...GADSDEN...GULF... HOLMES...INLAND WALTON...JACKSON...JEFFERSON...LAFAYETTE... LEON...LIBERTY...MADISON...TAYLOR...WAKULLA...WASHINGTON. GM...NONE. && $$ BLOCK/GIBBS