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000 FXUS62 KTAE 291916 AFDTAE AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE TALLAHASSEE FL 316 PM EDT WED OCT 29 2008 .SYNOPSIS... THE 18 UTC REGIONAL SURFACE ANALYSIS SHOWED A HIGH PRESSURE RIDGE OVER THE SOUTHEAST U.S. WITH A 1030 MB HIGH CENTERED ALONG THE LA- MS BORDER. VAPOR IMAGERY AND UPPER AIR DATA SHOWED SINKING NORTHWEST FLOW OVER MUCH OF THE SOUTHEAST BETWEEN AN UNUSUALLY DEEP TROUGH OVER THE EASTERN U.S. AND A RIDGE OVER THE ROCKY MOUNTAIN STATES. && .SHORT TERM... (TONIGHT THROUGH SATURDAY) THE AFOREMENTIONED HIGH PRESSURE CENTER WILL DISSIPATE OVER THE GULF COAST TONIGHT AND THURSDAY MORNING AS A NEW CENTER DEVELOPS OVER THE MID ATLANTIC STATES. ALTHOUGH THE PRESSURE GRADIENT WILL BEGIN TO INCREASE AS A RESULT...WINDS WILL LIKELY REMAIN CALM UNTIL AFTER SUNRISE...ALLOWING FOR ANOTHER NIGHT OF STRONG RADIATION COOLING. THE RAW MODEL OUTPUT FROM THE GFS AND NAM ARE HAVING THEIR USUAL PROBLEM WITH BRINGING SURFACE TEMPERATURES UP TOO QUICKLY AS THE HIGH PRESSURE CENTER RE-DEVELOPS TO THE NORTHEAST...SO WE WILL NOT USE THEIR BIAS CORRECTED GRIDS IN THIS FORECAST PACKAGE. THE MAV AND MET TEMPERATURES LOOK MORE REALISTIC...AND MAY EVEN BE SLIGHTLY WARM GIVEN THE FAVORABLE SETUP FOR STRONG COOLING. WE EXPECT A FEW OF THE NORMALLY COLDER INLAND SITES (TALLAHASSEE REGIONAL AIRPORT...CRESTVIEW...AND CROSS CITY...ETC.) TO BRIEFLY REACH" onClick="return popup(this, 'notes')">REACH FREEZING BY DAWN...BUT FREEZING CONDITIONS WILL NOT BE WIDESPREAD AND/OR LONG ENOUGH TO WARRANT A FREEZE WARNING. HOWEVER...FROST WILL BE WIDESPREAD ENOUGH TO WARRANT A FROST ADVISORY. A SLOW AND WEAK WARMING TREND WILL BEGIN THURSDAY AFTERNOON...BUT IT MAY STILL BE COLD ENOUGH IN A FEW SPOTS FOR A LITTLE FROST FRIDAY MORNING. TEMPERATURES WILL REMAIN BELOW AVERAGE THROUGH SATURDAY...BUT NOT AS COLD AS THE PAST FEW DAYS. IT LOOKS LIKE GOOD TRICK-OR-TREATING WEATHER FRIDAY EVENING...WITH TEMPERATURES IN THE UPPER 50S...LOW RELATIVE HUMIDITY...AND FAIR WEATHER. CLOUDS WILL BEGIN TO INCREASE FROM EAST TO WEST ON SATURDAY AS ATLANTIC MOISTURE INCREASES FROM NORTHEAST LOW LAYER WINDS...WHILE AN UPPER LEVEL LOW CUTS OFF OVER THE GULF OF MEXICO. .LONG TERM... (SATURDAY NIGHT THROUGH WEDNESDAY) THERE ARE TWO SCHOOLS OF THOUGHT ON THE EVOLUTION OF THIS CUT-OFF ENERGY OVER THE GULF. THE GFS IS INDICATING A DEEPER AND LESS PROGRESSIVE SYSTEM WHICH HOLDS IN THE VICINITY THROUGH MONDAY NIGHT. THE ECMWF IS SHOWING A LESS ORGANIZED AND MORE PROGRESSIVE SYSTEM WHICH HAS A BRIEF STAY OVER THE EASTERN GULF AND WHOSE INFLUENCE EXITS EAST BY THE END OF SUNDAY. TO SOME DEGREE THIS FASTER AND WEAKER SCENARIO HAS SOME SUPPORT FROM THE LATEST 00Z CANADIAN WHICH IS QUITE PROGRESSIVE WITH ITS SOLUTION. DESPITE THE DIFFERENCES IN PATTERN ALOFT THE SURFACE PATTERNS ARE QUITE SIMILAR. SURFACE HIGH PRESSURE RIDGING INTO THE AREA FROM THE NORTH SHOULD BE RE-ENFORCED BY EARLY NEXT WEEK AS ANOTHER STRONG HIGH DROPS SOUTHEAST THROUGH THE GREAT LAKES. WILL USE AN ENSEMBLE APPROACH THIS WEEKEND AND EXIT THE SYSTEM NOT AS FAST AS THE ECMWF BUT FASTER THAN THE GFS. ALLOWING FOR THIS SOMEWHAT SLOWER SOLUTION...WILL HAVE TO INTRODUCE SOME SLIGHT/CHANCE POPS TO THE SOUTHEAST HALF OF THE AREA SUNDAY AND MONDAY... MAINLY SOUTHEAST OF A LINE FROM TIFTON TO BAINBRIDGE AND PANAMA CITY. UNDER THIS SCENARIO THE GFS WOULD INDICATE A BROAD AREA OF DEEP LAYER Q-G FORCING OVER THE EASTERN ZONES AND IS ALSO SHOWING SOME FAIRLY SIGNIFICANT ISENTROPIC UPGLIDE THROUGH THE LOWER/MID-LEVELS. THIS LIFT WOULD BE FED BY ABUNDANT ATLANTIC MOISTURE ADVECTING WESTWARD ALONG THE SOUTHERN PERIPHERY OF THE SURFACE RIDGE. THE RESULT WOULD BE MAINLY SHALLOW AND FAST MOVING SHOWERS. FORECAST DETAILS AS TO WHERE THIS MOISTURE/FORCING WILL BE MAXIMIZED ARE IMPOSSIBLE AT THIS TIME WITH THE TIMING/EVOLUTION DIFFERENCES WITHIN THE GLOBAL MODELS. WITH THIS IN MIND WILL AVOID DETAILS AND KEEP THE GRIDS RATHER BROAD. ALL GUIDANCE HAS THE SYSTEM WELL TO THE NORTHEAST BY TUESDAY NIGHT WITH STACKED RIDGING RETURNING TO MUCH OF THE SOUTHEAST. && .AVIATION... MOSTLY CLEAR SKIES WITH VFR CONDITIONS WILL BE EXPECTED THROUGH THE PERIOD AS HIGH PRESSURE REMAINS IN CONTROL ACROSS THE REGION. THE WINDS WILL GRADUALLY VEER AROUND TOWARD THE NORTHEAST AND REMAIN LIGHT THROUGH THURSDAY. && .MARINE... A HIGH PRESSURE CENTER WILL DISSIPATE OVER THE GULF COAST TONIGHT AND THURSDAY MORNING AS A NEW CENTER DEVELOPS OVER THE MID ATLANTIC STATES. THIS CHANGE IN POSITION OF THE HIGH PRESSURE CENTER WILL CAUSE THE WINDS AND SEAS TO INCREASE BY THURSDAY NIGHT...ESPECIALLY OVER THE OFFSHORE WATERS. && .FIRE WEATHER... RED FLAG CONDITIONS ARE EXPECTED AGAIN THURSDAY ACROSS NORTHWEST FLORIDA DUE TO LONG DURATIONS OF RELATIVE HUMIDITY. KBDI VALUES IN SOUTHEAST ALABAMA AND LOWER WIND SPEEDS IN SOUTH GEORGIA WILL PREVENT RED FLAG CRITERIA FROM BEING REACHED THROUGH THE REMAINDER OF THE WEEK. THERE WILL BE A SLIGHT INCREASE IN LOW-LEVEL MOISTURE ACROSS THE EASTERN PORTIONS OF THE AREA THROUGH THE WEEKEND. && .PRELIMINARY POINT TEMPS/POPS... TALLAHASSEE 32 71 41 71 44 / 0 0 0 0 0 PANAMA CITY 41 71 49 72 49 / 0 0 0 0 10 DOTHAN 36 70 42 70 42 / 0 0 0 0 0 ALBANY 35 69 39 70 40 / 0 0 0 0 0 VALDOSTA 33 70 41 71 44 / 0 0 0 0 0 CROSS CITY 31 73 44 75 48 / 0 0 0 0 10 && .TAE WATCHES/WARNINGS/ADVISORIES... AL...FROST ADVISORY FROM 1 AM TO 7 AM CDT THURSDAY FOR THE FOLLOWING ZONES: COFFEE...DALE...GENEVA...HENRY...HOUSTON. GA...FROST ADVISORY FROM 2 AM TO 8 AM EDT THURSDAY FOR THE FOLLOWING ZONES: BAKER...BEN HILL...BERRIEN...BROOKS...CALHOUN... CLAY...COLQUITT...COOK...DECATUR...DOUGHERTY...EARLY... GRADY...IRWIN...LANIER...LEE...LOWNDES...MILLER... MITCHELL...QUITMAN...RANDOLPH...SEMINOLE...TERRELL... THOMAS...TIFT...TURNER...WORTH. FL...FROST ADVISORY FROM 2 AM EDT /1 AM CDT/ TO 8 AM EDT /7 AM CDT/ THURSDAY FOR THE FOLLOWING ZONES: BAY...CALHOUN...COASTAL WALTON...DIXIE...FRANKLIN...GADSDEN...GULF...HOLMES... INLAND WALTON...JACKSON...JEFFERSON...LAFAYETTE...LEON... LIBERTY...MADISON...TAYLOR...WAKULLA...WASHINGTON. RED FLAG WARNING UNTIL 7 PM EDT /6 PM CDT/ THIS EVENING FOR THE FOLLOWING ZONES: BAY...CALHOUN...DIXIE...FRANKLIN... GADSDEN...GULF...HOLMES...INLAND WALTON...JACKSON... JEFFERSON...LAFAYETTE...LEON...LIBERTY...MADISON...TAYLOR... WAKULLA...WASHINGTON. RED FLAG WARNING FROM 1 PM EDT /12 PM CDT/ TO 7 PM EDT /6 PM CDT/ THURSDAY FOR THE FOLLOWING ZONES: BAY...CALHOUN... DIXIE...FRANKLIN...GADSDEN...GULF...HOLMES...INLAND WALTON...JACKSON...JEFFERSON...LAFAYETTE...LEON...LIBERTY... MADISON...TAYLOR...WAKULLA...WASHINGTON. GM...NONE. && $$ LONG TERM...MROCZKA AVIATION/FIRE WEATHER...GIBBS REST OF DISCUSSION...FOURNIER