000 WTNT41 KNHC 271451 TCDAT1 HURRICANE DANIELLE DISCUSSION NUMBER 25 NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL AL062010 1100 AM AST FRI AUG 27 2010 THE OVERALL CLOUD PATTERN OF DANIELLE HAS CHANGED LITTLE SINCE THE LAST ADVISORY. THE 15-20 NMI DIAMETER EYE REMAINS QUITE DISTINCT AND EMBEDDED IN THE CENTER OF THE CONVECTIVE CLOUD MASS. CLOUD TOPS HAVE STARTED TO COOL AND THE COLDEST CLOUD RING NOW ENCIRCLES THE EYE ABOUT 75 PERCENT. THE SATELLITE CURRENT INTENSITY ESTIMATE FROM TAFB WAS T6.0/115 KT. ADT ESTIMATES FROM UW-CIMSS ARE T5.9/114 KT AND AN ODT OF T6.1/117 KT FROM NHC. A BLEND OF THESE INTENSITY ESTIMATES SUPPORTS MAINTAINING AN INTENSITY OF 115 KT FOR THIS ADVISORY. AN AIR FORCE RESERVE RECON AIRCRAFT WILL INVESTIGATE DANIELLE THIS AFTERNOON AND PROVIDE A MORE ACCURATE ASSESSMENT OF THE INTENSITY. THE INITIAL MOTION ESTIMATE REMAINS 305/10. DANIELLE HAS MADE A FEW BRIEF WESTWARD WOBBLES DURING THE PAST FEW HOURS...BUT OVERALL THE MOTION REMAINS UNCHANGED. THE TRACK WAS NUDGED SLIGHTLY TO THE WEST THROUGH 36 HOURS MERELY TO ACCOUNT FOR THE SLIGHT WESTWARD POSITION AT 12Z. THE GUIDANCE MODELS REMAIN VERY TIGHTLY PACKED THROUGH 72 HOURS AND ARE CONSISTENT WITH DANIELLE BEGINNING RECURVATURE TO THE NORTHEAST BY 24-36 HOURS AS THE HURRICANE ROUNDS THE WESTERN PERIPHERY OF THE DEEP-LAYER SUBTROPICAL RIDGE SITUATED ALONG 30N LATITUDE. IT IS POSSIBLE THAT THE OUTFLOW OF DANIELLE ON THE EAST SIDE THAT IS CONVERGING INTO A BROAD MID-LATITUDE TROUGH TO ITS NORTHEAST COULD BUILD THE RIDGE SLIGHTLY WESTWARD DURING THE NEXT 24 HOURS. THE RESULT WOULD BE A MORE NORTHERLY MOTION AND SLOWER RECURVATURE THAN CURRENTLY INDICATED. HOWEVER...THE CYCLONE IS STILL EXPECTED TO REMAIN WELL TO THE EAST OF BERMUDA. AFTER RECURVATURE OCCURS...A STRONG MID-LEVEL TROUGH CURRENTLY OVER THE NORTHEASTERN U.S. IS FORECAST TO ACCELERATE DANIELLE QUICKLY TO THE NORTHEAST AND THEN CAPTURE THE SYSTEM AT HIGHER LATITUDES AND TURN IT MORE POLEWARD AFTER 96 HOURS AS A POWERFUL EXTRATROPICAL LOW PRESSURE SYSTEM. THE OFFICIAL FORECAST TRACK IS SIMILAR TO THE PREVIOUS ADVISORY TRACK THROUGH 72 HOURS...AND THEN A LITTLE FASTER AND MORE POLEWARD AT DAYS 4 AND 5...WHICH IS CONSISTENT WITH THE CONSENSUS MODEL...TVCN. DANIELLE IS EXPECTED TO MOVE INTO A REGION OF LOWER VERTICAL SHEAR OVER THE NEXT 24 HOURS AS IT APPROACHES THE SUBTROPICAL RIDGE AXIS. OUTFLOW REMAIN QUITE IMPRESSIVE AND THE IS BEING ENHANCED TO THE NORTH AND EAST AS THE FLOW INTERACTS WITH BROAD UPPER-LEVEL TROUGH LOCATED WELL TO THE NORTHEAST OF DANIELLE. GIVEN THE FAVORABLE UPPER-LEVEL FLOW PATTERN...DECREASING SHEAR...AND SSTS OF 29C... CONDITIONS APPEAR FAVORABLE FOR SOME SLIGHT STRENGTHENING TO OCCUR DURING THE NEXT 24 HOURS. HOWEVER...BY 36-48 HOURS...SOUTHWESTERLY VERTICAL SHEAR AHEAD OF THE U.S. EAST COAST TROUGH IS EXPECTED TO INCREASE TO 25-30 KT. THE COMBINATION OF THE INCREASING SHEAR AND DECREASING SSTS SHOULD INITIATE A STEADY WEAKENING TREND. IN THE 96-120 TIME PERIOD...DANIELLE IS EXPECTED TO TRANSITION INTO A POWERFUL EXTRATROPICAL CYCLONE OVER THE COLD WATERS OF THE NORTH ATLANTIC. THE OFFICIAL INTENSITY FORECAST IS A BLEND OF THE SHIPS-GFDL-HWRF INTENSITY MODELS. FORECAST POSITIONS AND MAX WINDS INITIAL 27/1500Z 26.9N 59.8W 115 KT 12HR VT 28/0000Z 27.9N 60.8W 115 KT 24HR VT 28/1200Z 29.5N 61.2W 115 KT 36HR VT 29/0000Z 31.5N 60.3W 110 KT 48HR VT 29/1200Z 34.3N 57.6W 95 KT 72HR VT 30/1200Z 38.0N 52.0W 80 KT 96HR VT 31/1200Z 40.5N 43.0W 65 KT 120HR VT 01/1200Z 46.0N 28.0W 60 KT...POST-TROP/EXTRATROP $$ FORECASTER STEWART