ZCZC MIATCDAT1 ALL TTAA00 KNHC DDHHMM HURRICANE DANIELLE DISCUSSION NUMBER 11 NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL AL062010 500 AM AST TUE AUG 24 2010 ALTHOUGH THE CLOUD PATTERN ASSOCIATED WITH DANIELLE IS NOT AS WELL ORGANIZED AS IT WAS SEVERAL HOURS AGO...LATEST DVORAK SATELLITE INTENSITY ESTIMATES FROM SAB AND TAFB ARE AT 77 AND 90 KT... RESPECTIVELY. THE CONVECTIVE ORGANIZATION OF THE CYCLONE HAS BEEN PULSATING FOR REASONS THAT ARE NOT WELL UNDERSTOOD...BUT THE OVERALL TREND IS INDICATIVE OF A GENERAL INTENSIFICATION. UPPER- LEVEL OUTFLOW IS WELL ESTABLISHED OVER THE EASTERN SEMICIRCLE BUT IS LESS DEFINED TO THE WEST. BASED UPON THE HIGHER SATELLITE INTENSITY ESTIMATES...THE ADVISORY INTENSITY IS INCREASED TO 85 KT. AN EYE FEATURE THAT FORMED EARLIER IS NO LONGER EVIDENT...BUT A 0434 UTC AMSR-E OVERPASS WAS HELPFUL IN LOCATING THE CENTER. THAT OVERPASS AND OTHER RECENT FIXES YIELD AN INITIAL MOTION SLIGHTLY TO THE LEFT OF THE PREVIOUS ESTIMATE...280/17. DANIELLE IS EXPECTED TO MOVE ON A GENERAL WEST-NORTHWESTWARD COURSE FOR THE NEXT 12 HOURS OR SO BUT IS FORECAST TO GRADUALLY TURN MORE TOWARD THE NORTHWEST WHEN IT BEGINS TO ENCOUNTER A WEAKNESS IN THE SUBTROPICAL RIDGE APPARENT IN WATER VAPOR IMAGERY BETWEEN 45-50W. DYNAMICAL MODEL GUIDANCE SHOWS THE BREAK IN THE RIDGE BECOMING MORE PRONOUNCED BY 48 HOURS WHEN A STRONGER MID-LATITUDE TROUGH AMPLIFIES OVER THE CENTRAL ATLANTIC. THE EVOLUTION OF THESE FEATURES SHOULD CAUSE DANIELLE TO DECELERATE AND TURN NORTH- NORTHWESTWARD LATER IN THE FORECAST PERIOD. THE OFFICIAL NHC TRACK FORECAST IS ESSENTIALLY AN UPDATE OF THE PREVIOUS PACKAGE AND LIES CLOSE TO THE MULTI-MODEL CONSENSUS. GLOBAL MODELS SHOW DANIELLE REMAINING IN A LOW VERTICAL WIND SHEAR ENVIRONMENT FOR THE NEXT 24 HOURS OVER WATER TEMPERATURES BETWEEN 28-29C. THESE FAVORABLE FACTORS SHOULD LEAD TO A CONTINUED INTENSIFICATION OF THE CYCLONE...AND THE SHIPS RI INDEX INDICATES A 35% CHANCE OF AN INCREASE IN INTENSITY OF 25 KT DURING THE NEXT 24 HOURS. BETWEEN 24-72 HOURS...SOME INCREASE IN SOUTHWESTERLY VERTICAL WIND SHEAR ASSOCIATED WITH AN UPPER-LEVEL TROUGH MOVING SOUTHWESTWARD OVER THE CENTRAL ATLANTIC COULD HALT THE CURRENT INTENSIFICATION OR POSSIBLY RESULT IN SOME WEAKENING. LATER IN THE PERIOD...THE NUMERICAL GUIDANCE SUGGESTS SOME SLIGHT REDUCTION IN SHEAR...BUT...GIVEN THE UNCERTAINTIES...THE OFFICIAL FORECAST DOES NOT SHOW RESTRENGTHENING IN 3-5 DAYS. THE OFFICIAL NHC WIND SPEED FORECAST IS SIMILAR TO BUT SLIGHTLY HIGHER THAN THE PREVIOUS ONE DURING THE FIRST 24 HOURS...AND UNCHANGED BEYOND THAT TIME. FORECAST POSITIONS AND MAX WINDS INITIAL 24/0900Z 15.9N 44.6W 85 KT 12HR VT 24/1800Z 16.9N 46.6W 95 KT 24HR VT 25/0600Z 18.6N 48.9W 105 KT 36HR VT 25/1800Z 20.5N 51.0W 100 KT 48HR VT 26/0600Z 22.3N 52.9W 100 KT 72HR VT 27/0600Z 25.5N 55.5W 95 KT 96HR VT 28/0600Z 28.0N 57.5W 95 KT 120HR VT 29/0600Z 31.5N 59.0W 95 KT $$ FORECASTER KIMBERLAIN NNNN
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