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| #145944 (Received by flhurricane at: 5:08 PM 14.Aug.2007) TCDAT4 TROPICAL STORM DEAN DISCUSSION NUMBER 6 NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL AL042007 500 PM EDT TUE AUG 14 2007 DEAN'S STRUCTURE HAS NOT IMPROVED DURING THE AFTERNOON. CONVECTION HAS WANED AND REMAINS ESPECIALLY LIMITED IN THE NORTHEASTERN SEMICIRCLE...THOUGH THIS MAY BE A DIURNAL FLUCTUATION. BOTH TAFB AND SAB GAVE DVORAK ESTIMATES OF T2.5 OR 35 KT...WHILE AN AMSU PASS AT 1623 UTC SUGGESTED A SUBSTANTIALLY STRONGER INTENSITY. GIVEN THE LACK OF CONVECTIVE VIGOR...THE INTENSITY OF DEAN IS KEPT AT 35 KT. INITIAL MOTION OF DEAN IS 265 DEGREES AT 18 KT...A BIT SLOWER THAN THE LAST ADVISORY. DEAN IS SOUTH OF A DEEP-LAYERED RIDGE WHICH SHOULD STEER THE CYCLONE TOWARD THE WEST OR WEST-NORTHWEST FOR THE NEXT FEW DAYS. THE MODEL GUIDANCE SHIFTED SOMEWHAT TO THE WEST AND FASTER COMPARED TO THE 06 UTC RUNS...PERHAPS DUE TO A WEAKER AND LESS DIGGING TROUGH OFF OF THE U.S. EAST COAST BY DAY 5. THE OFFICIAL TRACK FORECAST IS TO THE LEFT OF AND FASTER THAN THE PREVIOUS ADVISORY...BUT REMAINS TO THE RIGHT OF THE CONSENSUS OF THE GFS...GFDL...AND HWRF. COMPARED TO THE OTHER MODELS...TRACK SOLUTIONS FOR THE NOGAPS AND ECMWF ARE SLOWER BECAUSE THEY DO NOT APPEAR TO HAVE A GOOD HANDLE ON DEAN'S FAST INITIAL FORWARD SPEED. DEAN IS CURRENTLY EXPERIENCING MODERATE NORTHEASTERLY SHEAR...IS OVER 27.5C SSTS...AND IS WITHIN A MOIST ENVIRONMENT. THE SHEAR SHOULD DROP WHILE THE SSTS WARM OVER THE NEXT FEW DAYS...SO THE ENVIRONMENT APPEARS TO BE CONDUCIVE FOR GRADUAL INTENSIFICATION. THE INTENSITY FORECAST IS CLOSE A CONSENSUS OF THE HWRF... GFDL...SHIPS...AND LGEM THROUGH 72 HR. THEREAFTER...THE INTENSITY FORECAST RELIES PRIMARILY UPON THE GFDL AND LGEM MODELS. BY DAY 5...DEAN IS FORECAST TO BE A STRENGTHENING HURRICANE AND COULD REACH MAJOR HURRICANE STATUS BY THEN. FORECAST POSITIONS AND MAX WINDS INITIAL 14/2100Z 11.6N 41.0W 35 KT 12HR VT 15/0600Z 11.7N 43.6W 40 KT 24HR VT 15/1800Z 12.0N 46.9W 45 KT 36HR VT 16/0600Z 12.3N 50.2W 50 KT 48HR VT 16/1800Z 12.6N 53.5W 60 KT 72HR VT 17/1800Z 14.0N 59.5W 70 KT 96HR VT 18/1800Z 15.5N 64.5W 85 KT 120HR VT 19/1800Z 17.5N 69.5W 95 KT $$ FORECASTER LANDSEA/KNABB |
