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| #208142 (Received by flhurricane at: 11:09 PM 17.Aug.2008) TCDAT1 TROPICAL STORM FAY DISCUSSION NUMBER 10 NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL AL062008 1100 PM EDT SUN AUG 17 2008 AIR FORCE RECONNAISSANCE REPORTS NEAR 0000 UTC SHOWED LITTLE MOTION SINCE THE EARLIER FIXES. RECENT SATELLITE IMAGERY AND CUBAN RADAR DATA IMAGERY INDICATE THAT THE CENTER IS ILL-DEFINED AT THE MOMENT...AND SURFACE SYNOPTIC DATA SUGGEST THAT THE CIRCULATION IS SOMEWHAT ELONGATED FROM EAST TO WEST. STRONGEST CONVECTION IS OCCURRING JUST TO THE EAST AND NORTHEAST OF THE ESTIMATED CENTER. INITIAL MOTION IS A HIGHLY UNCERTAIN 305/9. THE TRACK FORECAST REASONING IS NOT MUCH DIFFERENT FROM EARLIER TODAY. FAY IS LIKELY TO TURN TOWARD THE NORTH ON THE WESTERN PERIPHERY OF A MID-LEVEL RIDGE. NOAA G-IV JET DATA SHOW MID-TROPOSPHERIC HEIGHT FALLS OVER THE SOUTHEASTERN GULF OF MEXICO WHICH ALSO SUPPORTS A TURN TOWARD THE NORTH. SOME OF THE TRACK MODELS SUCH AS THE GFDL MODEL HAVE SHIFTED...ONCE AGAIN...TO THE EAST. THERE HAVE OBVIOUSLY BEEN SOME RUN-TO-RUN CONSISTENCY PROBLEMS WITH OUR TRACK GUIDANCE...BUT THIS IS OFTEN THE CASE FOR WEAK TROPICAL CYCLONES IN THE MODEL INITIAL CONDITIONS. I HAVE NOT MADE MUCH OF A CHANGE TO THE OFFICIAL FORECAST WHICH REMAINS CLOSE TO THE DYNAMICAL MODEL CONSENSUS. WE HAVE BEEN CARRYING 45 KT FOR THE CURRENT INTENSITY SINCE EARLIER TODAY ALTHOUGH THERE HAVE BEEN NO RECENTLY OBSERVED FLIGHT-LEVEL WINDS TO SUPPORT THIS VALUE. HOWEVER IT IS BELIEVED THAT THESE WINDS ARE LIKELY OCCURRING IN THE STRONG CONVECTION NORTHEAST OF THE CENTER WHICH WAS NOT SAMPLED BY THE AIRCRAFT. AN UPPER-LEVEL LOW OVER THE EXTREME NORTHWESTERN CARIBBEAN SEA IS IMPEDING THE OUTFLOW OVER THE WESTERN PORTION OF THE TROPICAL CYCLONE AND MAY EVEN BE CAUSING SOME UPPER-LEVEL CONVERGENCE OVER THE STORM. ON THE OTHER HAND...THE SHIPS GUIDANCE INDICATES THAT VERTICAL SHEAR WILL DECREASE DURING THE NEXT DAY OR SO. THEREFORE SOME STRENGTHENING IS FORECAST WHILE FAY IS OVER WATER DURING THE EARLIER PART OF THE FORECAST PERIOD. BY 48 HOURS OR SO...SHEAR ASSOCIATED WITH AN UPPER-LEVEL TROUGH OVER THE EXTREME EASTERN GULF OF MEXICO IS FORECAST TO INCREASE...AND THIS SHOULD LIMIT INTENSIFICATION. THE OFFICIAL INTENSITY FORECAST IS A BLEND OF THE LATEST GFDL AND HWRF MODEL PREDICTIONS. IT SHOULD BE ADDED THAT THERE IS LOW CONFIDENCE IN THIS FORECAST HOWEVER. IT IS IMPORTANT NOT TO FOCUS ON THE EXACT FORECAST TRACK. A BETTER WAY OF ASSESSING YOUR RISK IS TO MAKE USE OF THE WIND SPEED PROBABILITIES. THESE DO NOT CHANGE SIGNIFICANTLY FOR GIVEN LOCATIONS WHEN SMALL ADJUSTMENTS ARE MADE TO THE TRACK FORECAST. FORECAST POSITIONS AND MAX WINDS INITIAL 18/0300Z 21.4N 80.6W 45 KT 12HR VT 18/1200Z 22.3N 81.7W 50 KT...INLAND 24HR VT 19/0000Z 23.8N 82.7W 55 KT 36HR VT 19/1200Z 25.3N 82.8W 65 KT 48HR VT 20/0000Z 27.0N 82.8W 70 KT 72HR VT 21/0000Z 30.5N 82.5W 50 KT...INLAND 96HR VT 22/0000Z 34.0N 82.5W 25 KT...INLAND 120HR VT 23/0000Z 37.5N 82.5W 20 KT...REMNANT LOW $$ FORECASTER PASCH/ROBERTS |
