000 WTNT41 KNHC 172105 TCDAT1 TROPICAL STORM FAY DISCUSSION NUMBER 9 NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL AL062008 500 PM EDT SUN AUG 17 2008 FAY HAS BECOME A LITTLE BETTER ORGANZIED IN SATELLITE AND RADAR IMAGERY THIS AFTERNOON...WITH INCREASED CURVED BANDS OF CONVECTION NEAR THE CENTER IN THE NORTHEASTERN SEMICIRCLE. HOWEVER...THERE ARE SINGS OF SOUTHWESTERLY VERTICAL WIND SHEAR AND DRY AIR ENTRAINMENT IN THE WESTERN SEMICIRCLE...WHERE THERE IS LITTLE IN THE WAY OF ORGANIZED CONVECTION OR STRONG WINDS. AN AIR FORCE RESERVE HURRICANE HUNTER AIRCRAFT RECENTLY REPORTED A CENTRAL PRESSURE OF 1003 MB...ALTHOUGH THE PLANE HAS NOT YET SAMPLED THE WINDS IN THE NORTHEASTERN QUADRANT. THE INITIAL INTENSITY REMAINS 45 KT BASED ON CONTINUITY AND A 45 KT SATELLITE INTENSITY ESTIMATE FROM TAFB. THE CENTER OF FAY SURGED TOWARD THE WEST-NORTHWEST DURING THE DAY...AT ONE TIME MOVING BETWEEN 18-20 KT. THAT MOTION APPEARS TO HAVE ENDED...AND THE INITIAL MOTION FOR THIS ADVISORY IS A SOMEWHAT UNCERTAIN 300/13. FAY IS APPROACHING A DEVELOPING WEAKNESS IN A LOW/MID LEVEL RIDGE OVER THE GULF OF MEXICO...WHICH IS DEVELOPING DUE TO A MID/UPPER-LEVEL TROUGH OVER THE SOUTHERN UNITED STATES. THIS PATTERN SHOULD ALLOW FAY TO TURN MORE NORTHWARD AFTER 24 HR... BUT THERE REMAINS SIGNIFICANT DISAGREEMENT BETWEEN THE MODELS ON HOW MUCH OF A TURN WILL OCCUR. THE ECMWF AND CANADIAN MODELS CONTINUE TO FORECAST A SHARPER TURN WITH LANDFALL IN SOUTHWESTERN FLORIDA...WITH THE ECMWF SHOWING FAY CROSSING TO THE ATLANTIC THEN MOVING WESTWARD TO HIT FLORIDA AGAIN. THE GFS AND GFDL HAVE SHIFTED WEST SINCE THEIR PREVIOUS RUNS...WHILE THE UKMET HAS SHIFTED A LITTLE TO THE EAST. THESE MODELS HAVE JOINED THE HWRF IN CALLING FOR A TRACK NEAR OR JUST OVER THE WEST COAST OF THE FLORIDA PENINSULA. THE NOGAPS CONTINUES TO FORECAST A NORTH-NORTHWESTWARD MOTION TOWARD THE FLORIDA PANHANDLE. OVERALL...THE GUIDANCE ENVELOPE HAS SHIFTED TO THE WEST SINCE THE PREVIOUS PACKAGE... POSSIBLY DUE TO THE CHANGE IN THE INITIAL POSITION CAUSED BY THE MOTION SURGE. THE FORECAST TRACK IS SHIFTED ABOUT 60 N MI TO THE WEST OF THE PREVIOUS PACKAGE...BUT LIES TO THE EAST OF THE CENTER OF THE GUIDANCE ENVELOPE AND THE CONSENSUS MODELS. THE NEW TRACK IS IN BEST AGREEMENT WITH THE HWRF. THE INTENSITY FORECAST REMAINS PROBLEMATIC. THE SHIPS MODEL NOW FORECASTS PERSISTENT WIND SHEAR DURING THE FORECAST PERIOD...WITH PERHAPS A PERIOD OF LIGHTER SHEAR FROM 18-48 HR. THE LARGE-SCALE MODELS HAVE A VARIETY OF SOLUTIONS FOR THE CURRENT UPPER-LEVEL TROUGH WEST OF FAY OVER THE GULF OF MEXICO AND THE CARIBBEAN...WITH NO CLEAR EVIDENCE AT THIS TIME OF WHICH IS CORRECT. IT APPEARS THE SHEAR WILL BE LIGHT ENOUGH TO ALLOW FAY TO GRADUALLY STRENGTHEN AS SHOWN IN THE GFDL MODEL...AND THE NEW INTENSITY FORECAST THUS CALLS FOR INTENSIFICATION ALONG THOSE LINES. IT SHOULD BE NOTED THAT THE HWRF CALLS FOR FAY TO BECOME A CATEGORY 2 HURRICANE OVER THE EASTERN GULF OF MEXICO...WHILE THE SHIPS MODEL FORECAST A PEAK JUST BELOW HURRICANE STRENGTH. THE FORECAST TRACK SITUATION IS SIMILAR TO THAT OF HURRICANE CHARELY FROM AUGUST 2004...IN THAT A SMALL CHANGE IN THE TRACK OF THE STORM COULD MAKE A BIG DIFFERENCE IN THE EVETUAL LANDFALL LOCATION. THE NHC WIND SPEED PROBABILITIES PRODUCT SHOWS ABOUT AN EQUAL CHANCE OF HURRICANE-FORCE WINDS FOR THE ENTIRE WEST COAST OF THE FLORIDA PENINSULA. FORECAST POSITIONS AND MAX WINDS INITIAL 17/2100Z 21.0N 80.2W 45 KT 12HR VT 18/0600Z 22.3N 81.7W 50 KT...INLAND 24HR VT 18/1800Z 23.8N 82.8W 55 KT...OVER WATER 36HR VT 19/0600Z 25.3N 83.1W 65 KT 48HR VT 19/1800Z 27.0N 83.2W 75 KT 72HR VT 20/1800Z 30.0N 83.0W 65 KT...INLAND 96HR VT 21/1800Z 33.5N 82.0W 30 KT...INLAND 120HR VT 22/1800Z 37.0N 82.0W 20 KT...INLAND REMNANT LOW $$ FORECASTER BEVEN