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| #146098 (Received by flhurricane at: 11:00 AM 15.Aug.2007) TCDAT4 TROPICAL STORM DEAN DISCUSSION NUMBER 9 NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL AL042007 1100 AM EDT WED AUG 15 2007 SATELLITE IMAGES INDICATE THAT DEAN HAS A SMALL CENTRAL DENSE OVERCAST CLOUD PATTERN. HINTS OF A BANDING EYE HAVE BEEN SEEN ON VISIBLE AND MICROWAVE IMAGERY...AND SATELLITE INTENSITY ESTIMATES HAVE BEEN INCREASING. THE CURRENT INTENSITY ESTIMATE OF 50 KT IS A BLEND OF TAFB/SAB SUBJECTIVE DVORAK ESTIMATES OF 45 KT AND AMSU/AODT ESTIMATES OF NEAR 55 KT. THE INITIAL MOTION IS ABOUT THE SAME AS BEFORE...275/17. A STRONG DEEP-LAYERED RIDGE LIES TO THE NORTH OF DEAN AND IS FORECAST TO REMAIN WELL-ESTABLISHED FOR THE NEXT FEW DAYS. NUMERICAL TRACK FORECAST MODELS HAVE COME INTO BETTER AGREEMENT THAT THE STORM WILL MAINTAIN THE SAME GENERAL MOTION FOR THE NEXT COUPLE OF DAYS. BEYOND THREE DAYS...THE FATE OF THE STORM WILL BE PARTIALLY CONTROLLED BY A MIDDLE-LEVEL TROUGH CURRENTLY OVER THE BAHAMAS. THIS TROUGH IS FORECAST TO CUT OFF INTO A LOW AND HEAD WESTWARD UNDER A BUILDING SOUTHEAST UNITED STATES HIGH. MOST OF THE GUIDANCE SHOWS THE LOW REMAINING FARTHER AWAY FROM DEAN WITH STRONGER RIDGING CONTINUING ACROSS THE SOUTHWESTERN ATLANTIC OCEAN THAN IN PREVIOUS MODEL RUNS. THIS SOLUTION WOULD FAVOR A MORE WESTWARD TRACK IN THE LONG-RANGE..AND THE OFFICIAL FORECAST IS SHIFTED IN THAT DIRECTION NEAR THE END OF THE FORECAST. STEADY INTENSIFICATION OF THIS SYSTEM SEEMS TO BE THE BEST BET AS VERTICAL WIND SHEAR IS FORECAST TO BE LIGHT BY ALL MODELS AND SEA SURFACE TEMPERATURES UNDER THE STORM START TO RISE. THE ONLY NEGATING FACTOR TO INTENSIFICATION MIGHT BE THE ATMOSPHERIC STABILITY AS SUGGESTED BY THE SHIPS MODEL. HOWEVER...INTENSITY GUIDANCE INDICATES THAT DEAN WILL BE A HURRICANE BEFORE IT ENTERS THE EASTERN CARIBBEAN. THE GFDL/HWRF/SHIPS MODELS ALL FORECAST DEAN TO BE A MAJOR HURRICANE BY DAY 5...AND SO DOES THE OFFICIAL FORECAST. FORECAST POSITIONS AND MAX WINDS INITIAL 15/1500Z 12.4N 46.0W 50 KT 12HR VT 16/0000Z 12.7N 48.6W 55 KT 24HR VT 16/1200Z 13.1N 52.2W 60 KT 36HR VT 17/0000Z 13.7N 55.8W 65 KT 48HR VT 17/1200Z 14.2N 59.2W 75 KT 72HR VT 18/1200Z 15.5N 66.0W 85 KT 96HR VT 19/1200Z 16.5N 72.0W 95 KT 120HR VT 20/1200Z 18.0N 78.0W 105 KT $$ FORECASTER BLAKE |
