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#371996 (Received by flhurricane at: 4:37 PM 28.Aug.2010) TCDAT1 HURRICANE DANIELLE DISCUSSION NUMBER 30 NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL AL062010 500 PM AST SAT AUG 28 2010 VISIBLE IMAGERY AND A METOP-A AMSU OVERPASS INDICATE THAT ONLY A FRAGMENT OF THE INNER EYEWALL EXISTS. THE AMSU IMAGE ALSO SHOWED THAT THE 45 NMI DIAMETER OUTER CONCENTRIC RING HAS ERODED OVER THE SOUTHWEST QUADRANT. THE DVORAK SATELLITE INTENSITY ESTIMATES HAVE DECREASED TO 90 KT FROM BOTH TAFB AND SAB...AND SO HAS THE INITIAL INTENSITY. SOUTHWESTERLY SHEAR APPEARS TO BE IMPINGING THE OUTFLOW OVER THE WESTERN HALF OF THE CYCLONE. THE SHEAR...ASSOCIATED WITH AN APPROACHING MID TO UPPER LEVEL TROUGH...SHOULD INCREASE LATER TONIGHT PREVENTING DANIELLE FROM RE-STRENGTHENING. THE INTENSITY FORECAST IS BASED ON THE ICON INTENSITY MODEL CONSENSUS AND REFLECTS GRADUAL WEAKENING THROUGH DAY 4 AS THE SYSTEM COMPLETES ITS TRANSITION INTO AN EXTRATROPICAL LOW...WITH LITTLE CHANGE IN INTENSITY THEREAFTER. THE INITIAL MOTION ESTIMATE IS NORTH-NORTHEASTWARD OR 030/11. DANIELLE HAS BEGUN TO ACCELERATE TOWARD THE NORTH-NORTHEAST IN RESPONSE TO A DEEP LAYER BAROCLINIC SYSTEM MOVING INTO THE WESTERN ATLANTIC OCEAN. A TEMPORARY DECREASE IN FORWARD SPEED IS FORECAST NEAR THE 36 PERIOD AS A MID-LEVEL RIDGE PASSES TO THE NORTH OF THE CYCLONE. AT DAY 3...ANOTHER CANADIAN PULSE IS EXPECTED TO MOVE OVER THE CANADIAN MARITIMES...CAUSING DANIELLE TO AGAIN ACCELERATE EAST-NORTHEASTWARD. THE AFOREMENTIONED SHORTWAVE TROUGH SHOULD INDUCE A SHARP TURN NORTHWARD TOWARD THE END OF THE FORECAST PERIOD. THE OFFICIAL NHC FORECAST HAS AGAIN BEEN ADJUSTED A LITTLE TO THE RIGHT OF THE PREVIOUS ADVISORY AND IS BASED ON A BLEND OF THE DYNAMICAL MODELS...PRIMARILY THE GFS...ECMWF...AND THE CANADIAN. INITIAL WIND RADII HAVE BEEN ADJUSTED USING A 1426 UTC ASCAT PASS. FORECAST POSITIONS AND MAX WINDS INITIAL 28/2100Z 30.3N 59.7W 90 KT 12HR VT 29/0600Z 32.3N 58.2W 90 KT 24HR VT 29/1800Z 36.1N 55.6W 85 KT 36HR VT 30/0600Z 38.8N 53.8W 75 KT 48HR VT 30/1800Z 40.3N 50.5W 65 KT 72HR VT 31/1800Z 45.0N 38.0W 60 KT 96HR VT 01/1800Z 53.0N 33.0W 55 KT...POST-TROP/EXTRATROP 120HR VT 02/1800Z 54.0N 41.0W 55 KT...POST-TROP/EXTRATROP $$ FORECASTER ROBERTS/AVILA |