FXUS62 KTAE 200057 AFDTLH AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE TALLAHASSEE FL 900 PM EDT SAT JUL 19 2003 LOCAL RADARS SHOW LAST OF THE CONVECTION MOVING ACROSS THE COASTAL COUNTIES OF THE BIG BEND AND COASTAL WATERS. SHOULD BE ABLE TO UPDATE ZONES SHORTLY TO REMOVE POPS. 00Z KTLH SOUNDING VERY MOIST WITH PWAT AT 2.05" ALONG WITH UNIDIRECTIONAL FLOW FROM THE WEST UP TO 500 MB. CLOUDS WILL BE THINNING ALL AREAS SO WILL PARTLY CLOUDY WILL BE ACCEPTED. MARINE: WINDS AT THE BUOYS ARE WEST NEAR 10 KNOTS WITH SEAS LESS THAN 2 FEET. NO CHANGES ANTICIPATED. BARRY PREVIOUS DISCUSSION FOLLOWS ******************************************************************** CURRENTLY: SCATTERED TSTORMS THAT DEVELOPED OVER THE PANHANDLE THIS MORNING HAVE CONTINUED TO DEVELOP AND PROGRESS EASTWARD. SOME STRONG STORMS ARE ALSO MOVING THROUGH AL AND WEST GA ZONES. THESE SHOWERS AND TSTORMS SHOULD CONTINUE TO MOVE EAST THIS AFTERNOON WITH THE MEAN STEERING FLOW. THUNDERSTORMS HAVE THE POTENTIAL TO PRODUCE HEAVY DOWNPOURS...GUSTY WINDS AND SMALL HAIL. SOME ISOLATED SEVERE STORMS ARE POSSIBLE THIS AFTERNOON. BY EVENING COVERAGE SHOULD BEGIN TO DIMINISH. MCS OVER MISSISSIPPI AND ALABAMA SHOULD PROGRESS SOUTH TODAY AND SE AL COULD SEE SOME STORMS IMPACT LATER TODAY/TONIGHT. FOR TOMORROW AFTERNOON SHOWERS AND THUNDERSTORMS ACROSS THE AREA ARE ON TAP. SOME STORMS MAY BE STRONG. THE UPPER LEVEL TROUGH REMAINS OVER THE EAST AND MODELS AMPLIFY THIS TROUGH EVEN MORE AND MOVE A LOW OUT OF CANADA INTO THE GREAT LAKES REGION. GFS CENTERS THE LOW A TAD LOWER OVER THE OHIO RIVER VALLEY AND THEN MOVES IT NORTHEAST. GFS IS MORE AGGRESSIVE WITH THIS LOW AND THE PRESSURE GRADIENT OVER THE SOUTHEAST. NOT BUYING INTO THE 25 KT WINDS OVER THE AREA JUST YET...BUT DO PICK THEM UP SOME. THE BASE OF THE TROUGH IS EXPECTED TO BE OVER THE AREA AND A FEW DISTURBANCES SHOULD SLIDE EAST OVER THE AREA...INCREASING RAIN CHANCES MONDAY THROUGH WEDNESDAY. BY THURSDAY TROUGH SHOULD MOVE EAST OF THE AREA ALLOWING FOR DRIER AIR AND A TAD QUIETER WEATHER IN THE CWA. .MARINE...LIGHT WINDS AND LOW SEAS PREVAIL. BY TUESDAY/WEDNESDAY TIME FRAME MAY SEE WINDS AND SEAS PICK UP SOME IN RESPONSE TO THE TROUGH DIGGING INTO THE SOUTHEAST. .FIRE WEATHER...RH VALUES REMAIN UP...NO HIGHLIGHTS. .PRELIMINARY POINT TEMPS/POPS... TLH 71 90 72 90 / 20 50 30 50 PFN 77 88 76 88 / 20 50 30 50 DHN 72 90 72 88 / 20 50 30 50 ABY 72 90 71 89 / 20 40 20 50 VLD 71 90 72 90 / 20 50 30 50 CTY 72 90 72 91 / 20 50 30 50 .TLH WATCHES/WARNINGS/ADVISORIES... AL...NONE. GA...NONE. FL...NONE. $$ BOLINSKI PREVIOUS DISCUSSION.************************************************* .OVERVIEW...12Z KTLH SOUNDING SHOWED SOME COOLING AT MID LEVELS OVER YESTERDAY MORNING. HOWEVER, MOISTURE IN THE COLUMN HAS INCREASED WITH THE PW UP TO 1.81 INCHES. MEAN VECTOR WINDS FROM 1000-700 MB ARE W 10-15 KT. MODIFIED SOUNDING RESULTS IN A CAPE OF 3734 J/KG. LOOKING AT THE SEA BREEZE CLIMATOLOGY FOR THIS FLOW REGIME, WE ARE RIGHT ON THE MONEY WRT MOISTURE, BUT THE CAPE IS NEARLY A STANDARD DEVIATION ABOVE NORMAL. PVA WILL ALSO ENHANCE RAIN CHANCES TODAY AS A VORT LOBE MOVES SE OVER THE AREA. .UPDATE...FOR THE ABOVE REASONS, BELIEVE MOS POPS ARE TOO LOW. HOWEVER, CURRENT FORECAST IS ALREADY ABOVE MOS, SO ONLY MINOR POP CHANGES, IF ANY, WILL BE NECESSARY. THE REMAINING FORECAST ELEMENTS ALSO LOOK ON TARGET. ONLY EXCEPTION IS SKY CONDITION. ANTICIPATE MOSTLY CLOUDY SKIES THIS AFTERNOON. .MARINE...WINDS SHOULD BE MORE SW THAN W TODAY OVER THE COASTAL WATERS. WILL MAKE THIS MINOR CHANGE TO THE FORECAST. WOOL PREVIOUS DISCUSSION FOLLOWS. ***************************************************************** 200 AM EDT SAT JUL 19 2003 .OVERVIEW... LARGE UPPER HIGH OVER THE WRN USA HAS MOVED LITTLE IN THE LAST 24 HOURS. A SPEED MAX DIVING SE ACROSS IA IS SPARKING AN MCS OVER MISSOURI. THIS SPEED MAX APPEARS TO BE DEEPENING THE BROAD TROUGH OVER THE NE USA. CLOSER TO HOME...WATER VAPOR IMAGES SHOW THE FAR SE USA IS IN A DEFORMATION ZONE BETWEEN THE MENTIONED UPPER HIGH AND TROUGH. A CYCLONIC SHEAR AXIS EXTENDS NE ACROSS THE GULF AND THROUGH NE FL. LOWER TROPOSPHERIC FLOW OVER THE CWFA IS MORE DEFINITELY SW PER LOCAL SOUNDINGS AND VAD WIND PROFILES. HOWEVER...BY NOTING THE H7 00Z RAOB PLOT AND TLH/JAN SOUNDINGS...IT CAN BE SEEN THAT A LOWER TROPOSPHERIC TROUGH ALSO EXISTS WITH ITS AXIS FARTHER W OF THE UPPER TROUGH. THE SURFACE PRESSURE GRADIENT ALSO A LITTLE TIGHTER...WITH EVIDENCE OF A WEAK PRESSURE TROUGH EXTENDING SW INTO OUR NW ZONES... AND AN OUTFLOW BOUNDARY MOVING INTO OUR FAR NE CWFA. .SHORT TERM... TODAY...SHORT RANGE MODELS PROG THE MID-LEVEL TROUGH OVER THE WRN CWFA TO SHARPEN TODAY WITH THE APPROACH OF THE MENTIONED SPEED MAX. LOWER TROPOSPHERIC MEAN FLOW IS PROGGED TO BECOME SO CYCLONIC WE MAY END UP HAVING A BORDERLINE DISTURBED DAY. MEAN H10-H7 FLOW OVER OUR WRN WATERS IS ACTUALLY PROGGED TO VEER FROM SW TO NW BY THIS EVENING PER GFS/ETA. NONETHELESS...WILL FOLLOW THE REGIME 4 OR 5 SCENARIO FOR OUR LOCAL SEABREEZE CLIMATOLOGY. BOTH SCENARIOS INVOLVE MEAN SW FLOW AND ~50% POPS FOR FL ZONES AND FAIRLY HIGH POPS ALSO FOR OUR AL ZONES. PROGGED SOUNDINGS HAVE MOISTURE AND INSTABILITY VALUES NEAR OR ABOVE CLIMATOLOGY. SUNDAY...THERE IS MORE DISCREPANCY AMONG THE SHORT RANGE MODELS REGARDING THE FLOW REGIME. ETA IS THE OUTCAST WITH NW FLOW...WHEREAS GFS AND NGM KEEP SW FLOW. DO BELIEVE THERE WILL BE A SLIGHT NW COMPONENT. THERMODYNAMICS ARE JUST AS GOOD...SO WILL KEEP 50% OVER FL AND 40% OVER REMAINING ZONES. .MARINE... NO HIGHLIGHTS. .FIRE WEATHER... NO HIGHLIGHTS. .EXTENDED... NO CHANGES MADE. .PRELIMINARY POINT TEMPS/POPS... TLH 92 71 91 74 / 50 20 50 30 PFN 90 74 88 76 / 50 20 50 30 DHN 90 72 90 74 / 50 20 50 30 ABY 90 72 90 73 / 50 20 40 30 VLD 93 71 90 73 / 50 20 40 30 CTY 90 72 90 73 / 50 20 50 30 $$ TJT