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000 FXUS62 KMFL 201726 AFDMFL AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE MIAMI FL 126 PM EDT SAT SEP 20 2008 .AVIATION...VFR CONDITIONS WILL PREVAIL NEXT 24 HOURS WITH ONLY A FEW QUICK PASSING SHRA FOR POSSIBLY BRIEF MVFR CIG/VSBY AT ALL S FLA TERMINALS THROUGH 23Z AND THEN OVERNIGHT AT THE E CST SITES. E FLOW HAS WEAKENED TODAY WITH SPEEDS OF 10KT OR LESS AND THIS SHOULD ALLOW W CST SEA BREEZE TO SET UP AT KAPF AT AROUND 19Z PERSISTING UNTIL AROUND 23Z WHEN THEIR WIND WILL SHIFT BACK TO LIGHT E AGAIN. SLIGHTLY MORE MOIST AIRMASS WILL WORK ITS BACK ACROSS FLA TONIGHT INTO EARLY SUNDAY AND THIS WILL ALLOW ISOLD TO SCT SHRA TO CONTINUE AFFECTING E CST TERMINALS SO HAVE KEPT VCSH IN ALL THE E TERMINALS THROUGH THE PERIOD. 30/KOB && .PREV DISCUSSION... /ISSUED 1032 AM EDT SAT SEP 20 2008/ UPDATE... ONLY MINOR MODIFICATIONS WERE MADE TO THE GRIDS THIS MORNING... WITH THE MOST SIGNIFICANT CHANGE BEING THE LOWERING OF POPS AND REMOVAL OF THUNDER...BASED ON DATA SEEN IN THE 20/12Z KMFL RAOB. THE LOCAL ATMOSPHERE APPEARS TO BE SUBSTANTIALLY DRIER AND MORE STABLE TODAY COMPARED TO WHAT WE HAVE SEEN RECENTLY...AND ALTHOUGH SHOWERS REMAIN A DISTINCT POSSIBILITY...THE THREAT FOR THUNDERSTORMS IS TOO LOW TO INCLUDE IN THE PUBLIC FORECAST AT THIS TIME. OTHERWISE...MADE SUBTLE CHANGES TO THE WIND AND CLOUD COVER GRIDS TO ACCOUNT FOR CURRENT TRENDS...BUT BOTH TEMPERATURE AND DEW POINT GRIDS LOOK GOOD AT THIS TIME. UPDATED PRODUCTS WILL BE ISSUED SHORTLY. 70/DD AVIATION DISCUSSION... /ISSUED 729 AM EDT SAT SEP 20 2008/ AVIATION...A FEW SHRA CONTINUE TO DEVELOP OVER THE ATLANTIC AND THEN MOVE ONSHORE IN THE LIGHT EASTERLY FLOW. THUS, HAVE PLACE VCSH IN ALL E CST TAFS ALTHOUGH THE ACTIVITY IS VERY ISOLD IN NATURE. SCT TSRA ARE EXPECTED TO DEVELOP AFT 14Z WITH VCTS IN THE E TERMINALS AS A RESULT. E FLOW HAS WEAKENED DURING THE PAST 24 HOURS BUT NONE OF THE MODEL GUIDANCE SHOWS A W CST SEA BREEZE FROM DEVELOPING SO HAVE NOT INCLUDED IN THE KAPF TAF BUT WILL EXAMINE THIS AGAIN PRIOR TO THE 18Z TAF ISSUANCE. 30/KOB PREV DISCUSSION... /ISSUED 407 AM EDT SAT SEP 20 2008/ DISCUSSION...A WEAKENING UPPER TROUGH OF LOW PRES TO THE NE OF S FLA WILL CONTINUE TO MOVE NE LEAVING THE AREA BETWIXT A LARGE ATLC RIDGE EXTENDING FROM THE CENTRAL ATLC SW OVER HISPANIOLA... AND AN UPPER TROUGH OVER THE U.S. THAT EXTENDS FROM THE GREAT LAKES SW INTO THE LOWER MS RIVER VALLEY. THIS PERSISTS THROUGH SUN. THE CONTINENTAL UPPER TROUGH DISSIPATES AND AN UPPER RIDGE...NOW EXTENDING FROM THE DESERT SW ACROSS THE SOUTHERN GREAT PLAINS THEN NE INTO THE GREAT LAKES...WILL MON THROUGH THU. A TROUGH DEVELOPS TO THE E OF THE U.S. RIDGE AND DIGS SOUTHWARD ALONG THE U.S. E SEABOARD WITH A CLOSED UPPER LOW DEVELOPING OVER THE ATLC OFF OF THE CAROLINAS TOWARD MID-WEEK. FOR THE SHORT TERM...TODAY THROUGH MON...S FLA WILL BE A LITTLE DRIER THAN NORMS TODAY AS S FLA STILL UNDER THE EFFECT OF DRY AIR ALOFT AS A WEAK SHORT WAVE RIDGE MOVES OVER THE AREA IN THE WAKE OF THE UPPER TROUGH PULLING/DISSIPATING TO THE NE. AS THE TROUGH MOVES NE...AN INVERTED SURFACE TROUGH ASSOCIATED WITH THE SYSTEM TO THE E OF S FLA MOVES OVER S FLA LATE SUN INTO MON WITH AN INCREASE IN MOISTURE AND CHANCES OF RAIN. MAX TEMPS NEAR NORMS BUT E COAST MIN TEMPS A TAD BIT ABOVE. EXTENDED PERIOD...TUE THROUGH FRI...S FLA REMAINS IN THE COL BETWEEN THE CONTINENTAL RIDGE AND THE ATLC RIDGE. THUS SOME UPPER INSTABILITY WITH AMPLE ATMOSPHERIC MOISTURE COMBINE TO KEEP S FLA IN A SITUATION OF MAINLY AFTERNOON SHOWERS AND THUNDERSTORMS INTERIOR AND W WITH MAINLY E COAST NOCTURNAL ACTIVITY. MARINE...NE/E WINDS AROUND 10 KNOTS WITH SEAS 2 TO 4 FEET TODAY THROUGH SUN NGT. SEAS 4 FEET OR LESS EXCEPT SEAS TO 5 FEET OFF OF PALM BEACH COUNTY AS 2 TO 3 FOOT SWELLS GENERATED BY THE LOW PRES E OF JAX IMPACT THE LOCAL AREA WATERS. WAVES AND SWELLS DECREASE MON. FIRE WEATHER...NO CONCERNS WITH RH REMAINING ABOVE CRITICAL VALUES. && .PRELIMINARY POINT TEMPS/POPS... WEST PALM BEACH 78 89 76 88 / 30 50 30 40 FORT LAUDERDALE 80 88 77 88 / 30 40 30 40 MIAMI 78 89 77 89 / 30 40 30 40 NAPLES 74 91 74 91 / 20 50 30 40 && .MFL WATCHES/WARNINGS/ADVISORIES... FL...NONE. AM...NONE. GM...NONE. && $$