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| #146154 (Received by flhurricane at: 4:59 PM 15.Aug.2007) TCDAT4 TROPICAL STORM DEAN DISCUSSION NUMBER 10 NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL AL042007 500 PM EDT WED AUG 15 2007 DEAN CONTINUES TO ORGANIZE THIS AFTERNOON. ALTHOUGH THE CLOUD TOPS HAVE WARMED RECENTLY...THE LAST FEW VISIBLE SATELLITE PICTURES INDICATE A TIGHTLY CURVED BAND WRAPPING AROUND THE CENTER. AMSU AND TRMM MICROWAVE IMAGES HAVE ALSO SUGGESTED THE FORMATION OF A PARTIAL EYEWALL. MOST OBJECTIVE AND SUBJECTIVE DVORAK INTENSITY ESTIMATES ARE INCREASING...AND THE CURRENT INTENSITY IS RAISED TO 55 KT. THE INITIAL MOTION HAS SHIFTED MORE TO THE WEST-NORTHWEST IN THE PAST SIX HOURS...AROUND 285/19. THIS MOVEMENT TOWARD THE WEST-NORTHWEST IS EXPECTED TO BE BRIEF AS DEEP-LAYERED RIDGING TO THE NORTH OF DEAN STRENGTHENS OVERNIGHT...FORCING THE STORM ON MORE OF A WESTWARD COURSE TOMORROW. THE GLOBAL MODELS NOW SUGGEST THAT ANY INTERACTION WITH A MIDDLE-LEVEL TROUGH CURRENTLY OVER THE BAHAMAS WILL BE LIMITED AS THAT FEATURE IS FORECAST TO ADVANCE WESTWARD AS AN INVERTED TROUGH WELL AHEAD OF DEAN. NUMERICAL TRACK GUIDANCE IS IN VERY GOOD AGREEMENT WITH THIS SCENARIO...SHOWING THE STORM IN THE VICINITY OF THE NORTHWESTERN CARIBBEAN SEA IN ABOUT 5 DAYS. THE OFFICIAL FORECAST IS SHIFTED A LITTLE TO THE NORTH DURING THE FIRST 36 HOURS...BUT IS MUCH FASTER AND TO THE WEST OF THE PREVIOUS TRACK NEAR THE END OF THE PERIOD. IT IS WORTH NOTING THAT THE OFFICIAL FORECAST IS STILL SLOWER THAN THE NUMERICAL MODEL CONSENSUS. BASED ON WHAT WE THINK WE KNOW ABOUT INTENSITY CHANGE...THERE DO NOT SEEM TO BE TOO MANY INHIBITING FACTORS TO A FUTURE INTENSIFICATION OF DEAN. GLOBAL MODELS UNANIMOUSLY DEVELOP A LARGE UPPER-LEVEL ANTICYCLONE NEAR THE CENTER OF THE HURRICANE AS THE SYSTEM TRAVELS INTO THE CARIBBEAN SEA. IN COMBINATION WITH VERY DEEP WARM WATERS...THIS PATTERN WOULD FAVOR THE DEVELOPMENT OF A POWERFUL HURRICANE. THE OFFICIAL INTENSITY FORECAST IS HIGHER THAN THE PREVIOUS NHC FORECAST AND IS IN GOOD AGREEMENT WITH A CONSENSUS OF THE SHIPS...GFDL...HWRF...AND LGEM MODELS. FORECAST POSITIONS AND MAX WINDS INITIAL 15/2100Z 13.1N 47.9W 55 KT 12HR VT 16/0600Z 13.5N 50.8W 65 KT 24HR VT 16/1800Z 14.1N 54.7W 70 KT 36HR VT 17/0600Z 14.6N 58.6W 75 KT 48HR VT 17/1800Z 15.1N 62.3W 85 KT 72HR VT 18/1800Z 16.0N 69.5W 95 KT 96HR VT 19/1800Z 17.0N 76.0W 105 KT 120HR VT 20/1800Z 18.5N 83.0W 115 KT $$ FORECASTER BLAKE |
