AFDTAE AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE TALLAHASSEE FL 925 PM EDT THU JUL 28 2011 ...HOT AND HUMID WEATHER TO RETURN THIS WEEKEND WITH HEAT INDICES NEARING 110 DEGREES ON SATURDAY... .DISCUSSION...A 597-DM UPPER LEVEL HIGH IS CENTERED OVER THE SRN APPALACHIANS THIS EVENING AND RIDGES SEWD TO THE NRN BAHAMAS. WATER VAPOR IMAGERY SHOWS THAT DRIER MID/UPPER LEVEL AIR HAS PUSHED WWD FROM THE ATLANTIC ACROSS THE FL PENINSULA ON THE S SIDE OF THIS RIDGE. SURFACE ANALYSIS SHOWS THE SUBTROPICAL RIDGE EXTENDING FROM THE NW ATLANTIC WWD ALONG THE N FL BORDER AND GULF COAST. THIS IS MAINTAINING MOIST SLY ONSHORE INTO THE REGION FROM THE SURFACE UP TO ABOUT 500 MB PER THE LATEST 00Z KTAE SOUNDING. REGIONAL RADARS SHOW ISOLATED CONVECTION FROM S CENTRAL GA SWD TO THE MOUTH OF THE SUWANNEE RIVER IN AREAS WHERE OUTFLOW FROM EARLIER CONVECTION IS INTERACTING WITH THE E COAST SEA BREEZE. POPS WILL BE ADJUSTED TO SHOW SLIGHT CHANCE ACROSS THE ERN ZONES AND NIL TO THE W. TS DON CONTINUES TO MOVE OFF TO THE WNW AND IS FORECAST TO MAKE LANDFALL IN THE MIDDLE TX COAST FRI NIGHT. LOCAL IMPACTS HAVE BEEN LIMITED TO THE SURF ZONE AND MARINE AREA IN THE FORM OF INCREASED RIP CURRENT RISK AND S TO SSW SWELLS. && .MARINE...THE PRESSURE GRADIENT WILL CONTINUE TO DIMINISH AS DON MOVES FURTHER AWAY FROM THE AREA. SWELLS FROM DON APPEAR TO HAVE PEAKED AND WE ARE NOW BEGINNING A SLOW DOWNWARD TREND. WILL CONTINUE TO INCLUDE MAINLY SWELL WORDING IN THE FORECAST FOR TONIGHT AND FRI. SEAS SHOULD SUBSIDE BACK TO 2 TO 3 FEET BY SATURDAY WITH A FURTHER DECREASE EXPECTED BY THE END OF THE WEEKEND AS THE SUBTROPICAL RIDGE ONCE AGAIN BECOMES THE DOMINANT FEATURE OVER THE MARINE AREA. && .AVIATION...THROUGH 00Z SAT. SHOWER AND STORM ACTIVITY HAS LARGELY DISSIPATED ACROSS THE AREA... STILL A SLIGHT CHANCE OF A BRIEF SHOWER AROUND KVLD THROUGH 03-04Z...BUT OTHERWISE A DRY OVERNIGHT PERIOD EXPECTED. GUIDANCE IS IN GOOD AGREEMENT SHOWING VERY LITTLE IN THE WAY OF EXPECTED VIS/CIG RESTRICTION THROUGH THE EARLY MORNING HOURS. WITH ALL THE RAIN THE PAST FEW DAYS..SOIL MOISTURES ARE HIGH...SO PATCHY MVFR VIS RESTRICTIONS WILL BE POSSIBLE...ESPECIALLY TOWARD DAWN...BUT FOR THE MOST PART HAVE KEPT GENERAL VFR IN THE TAFS. VFR WILL PREVAIL THROUGH MUCH OF THE DAY FRIDAY AS WELL. ONLY EXCEPTIONS WILL BE IN PROXIMITY TO ANY TYPICAL AFTERNOON SHOWERS AND STORMS. && .FIRE WEATHER...DESPITE LOWER RAIN CHANCES AND HIGHER TEMPERATURES...RELATIVE HUMIDITY VALUES WILL REMAIN WELL ABOVE 35 PERCENT THROUGH THE WEEKEND. && .PREV DISCUSSION... 315 PM EDT THU JUL 28 2011 SYNOPSIS...18 UTC SURFACE ANALYSIS SHOWS OUR REGION ON THE WESTERN EDGE OF THE SUBTROPICAL RIDGE AXIS. TROPICAL STORM DON WAS CONTINUING TO MOVE WESTWARD AROUND 15 MPH ACROSS THE SOUTHERN GULF OF MEXICO. VISIBLE SATELLITE IMAGERY AND SURFACE DATA SHOW THAT THE EAST COAST SEA BREEZE IS BEGINNING TO SLOWLY ADVANCE WESTWARD...BUT WITH THE STORMS ENCOUNTERING DRIER MID LEVEL AIR IN PLACE ACROSS THE WESTERN FLA PENINSULA EXTENDING NORTHWARD INTO SOUTH CENTRAL GEORGIA...STORM COVERAGE IS REMAINING ISOLATED AT BEST. SHORT TERM...(TONIGHT THROUGH SATURDAY NIGHT). AFTER AN ACTIVE COUPLE OF DAYS WITH SHOWER AND THUNDERSTORM ACTIVITY...THINGS WILL BEGIN TO TRANSITION BACK TO A VERY HOT AND MOSTLY DRY PERIOD INTO THE WEEKEND...PROVIDING ONLY LOW END RAIN CHANCES TO HELP BEAT THE HEAT. OVERALL...THE MODELS ARE IN DECENT AGREEMENT THAT THE RIDGE OF HIGH PRESSURE ACROSS THE TENNESSEE VALLEY STRETCHING EASTWARD ACROSS THE SMOKIES WILL BUILD SOUTHEASTWARD TOWARD THE NE FLA COAST BY SATURDAY. THIS WILL RESULT IN WARMING TEMPERATURES. THIS RIDGE WILL ALSO SUPPLY INCREASING CONVECTIVE SUPPRESSION TO LIMIT SHOWER AND THUNDERSTORM ACTIVITY PRIMARILY TO THE SEA BREEZE ZONE. FRIDAY...DRIER MID LEVEL AIR LOCATED ACROSS THE FLORIDA PENINSULA WILL BEGIN TO WORK OVER THE REGION FROM THE EAST LIMITING SHOWER AND THUNDERSTORM DEVELOPMENT. LIGHT SOUTHEAST FLOW WILL APPLY SOME ENHANCEMENT TO THE SEA BREEZE IN THE FLA BIG BEND AND PANHANDLE...BUT WITH THE MAGNITUDE OF THIS FLOW BEING RATHER LIGHT...THE SEA BREEZE FRONT ISN`T EXPECTED TO MAKE SIGNIFICANT INLAND PROGRESS. DUE TO THE COMBINATION OF A SLIGHTLY LESS FAVORABLE THERMODYNAMIC ENVIRONMENT AND THE LACK OF A SEA BREEZE MOVING INTO SOUTH GA/SE AL...WILL LEAVE POPS ONLY IN THE 20 PERCENT RANGE THERE...WITH 30 PERCENT POPS IN FLA. TEMPERATURES WILL BE ON THE WAY UP...BUT NOT QUITE AS WARM AS EXPECTED ON SATURDAY...WITH MOST INLAND SITES IN THE MID 90S. HEAT INDICES WILL APPROACH 105 IN THE AFTERNOON. SATURDAY...THIS WILL LIKELY BE THE HOTTEST DAY OF THE WEEKEND WITH THE CORE OF THE MID LEVEL RIDGE PARKED DIRECTLY OVER THE REGION INTO THE AFTERNOON. LIGHT AND VARIABLE FLOW WILL LIKELY CONFINE SHOWER AND THUNDERSTORM ACTIVITY IN THE AFTERNOON TO AREAS NEAR THE COAST. THUS...WITH LITTLE CONVECTIVE ACTIVITY AND THE RIDGE NEARLY OVERHEAD...EXPECT AFTERNOON TEMPERATURES TO WARM INTO THE UPPER 90S AND LOW 100S ACROSS THE INTERIOR WITH MID 90S AT THE COAST. WITH THE HUMID TROPICAL AIRMASS REMAINING IN PLACE AT THE SURFACE...DEWPOINTS WILL LIKELY ONLY MIX OUT TO THE LOWER 70S IN THE AFTERNOON AWAY FROM THE COAST. THIS WILL RESULT IN HEAT INDICES IN THE 107 TO 111 DEGREE RANGE. THIS WILL APPROACH OUR HEAT ADVISORY CRITERIA...SO WE`LL CONTINUE TO MONITOR THIS CLOSELY IN FUTURE FORECASTS. LONG TERM...(SUNDAY THROUGH THURSDAY). MODELS ARE IN GENERAL AGREEMENT EARLY IN THE PERIOD. AS DISCUSSED ABOVE A RATHER WARM WEEKEND IS IN STORE AND THIS WILL CONTINUE INTO SUNDAY. BY MONDAY...THINGS BEGIN TO TAPER BACK ON TEMPERATURES AS THE UPPER LEVEL HIGH PRESSURE RETREATS BACK TO THE WEST. SEA BREEZE ACTIVITY WILL BE A FACTOR EACH DAY THROUGH THE ENTIRE PERIOD AS NO STRONG WEATHER DISTURBANCES ARE SLATED TO MOVE THROUGH THE AREA. MID-LEVEL MOISTURE ALSO REMAINS HIGH SO SEA-BREEZE ACTIVITY WILL BE SOMEWHAT ENHANCED AS WELL. FOR THIS REASON THE POPS THROUGH THE EXTENDED PERIOD HAVE BEEN ADJUSTED WITH LOCAL SEA-BREEZE CLIMATOLOGY NUMBERS. && .PRELIMINARY POINT TEMPS/POPS... TALLAHASSEE 75 96 76 99 77 / 20 30 10 30 10 PANAMA CITY 78 90 78 94 79 / 20 20 10 30 10 DOTHAN 75 97 76 98 76 / 30 20 10 20 10 ALBANY 76 97 76 100 77 / 10 20 10 20 10 VALDOSTA 75 97 75 101 77 / 10 20 10 30 10 CROSS CITY 74 94 76 96 77 / 10 30 10 30 10 APALACHICOLA 79 90 79 93 80 / 20 20 10 30 10 && .TAE WATCHES/WARNINGS/ADVISORIES... AL...NONE. GA...NONE. FL...NONE. GM...NONE. && $$