000 WTNT41 KNHC 302034 TCDAT1 TROPICAL STORM DANIELLE DISCUSSION NUMBER 38 NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL AL062010 500 PM AST MON AUG 30 2010 DANIELLE IS STUBBORNLY HOLDING ON TO TROPICAL CYCLONE STATUS THIS AFTERNOON. THE CONVECTIVE ENVELOPE HAS BECOME MORE SYMMETRIC SINCE YESTERDAY AND RELATIVELY DEEP CONVECTION CONTINUES NEAR THE CENTER OF THE CYCLONE. USING A SHEAR PATTERN...THE TAFB DVORAK CURRENT INTENSITY ESTIMATE INDICATED A 3.5...OR 55 KT. AN AMSU MEASUREMENT OF THE WARM CORE INDICATED 62 KT AT 1616Z USING THE CIMSS TECHNIQUE. BASED UPON A BLEND OF THESE...DANIELLE IS DOWNGRADED TO A 60 KT TROPICAL STORM AT THIS TIME. A 1340Z ASCAT PASS ALLOWED US TO CONTRACT IN THE 34 AND 50 KT WIND RADII SOMEWHAT. EXTRATROPICAL TRANSITION SHOULD PROCEED QUICKLY THIS EVENING. ALL AVAILABLE GLOBAL MODEL FIELDS ALONG WITH THE USE OF THE FSU CYCLONE PHASE SPACE DIAGRAMS INDICATE THAT DANIELLE SHOULD BECOME FULLY EXTRATROPICAL BY EARLY TUESDAY...AS A SIGNIFICANT BAROCLINIC ZONE DEVELOPS JUST TO THE NORTHWEST OF THE SYSTEM. DANIELLE SHOULD REMAIN A LARGE CYCLONE AFTER EXTRATROPICAL TRANSITION WITH PEAK INTENSITY JUST BELOW HURRICANE FORCE FOR A DAY OR SO. THE CYCLONE IS CURRENTLY MOVING EAST-NORTHEASTWARD AT ABOUT 13 KT. THE SYSTEM HAS BECOME CAPTURED BY A VIGOROUS SHORT-WAVE TROUGH...WHICH SHOULD ACCELERATE IT TOWARD THE EAST-NORTHEAST FOR THE NEXT TWO DAYS. A TURN TOWARD THE NORTH BY DAY THREE IS ANTICIPATED AND THE SYSTEM BECOMES ABSORBED BY A VERY LARGE EXTRATROPICAL CYCLONE BY DAY FOUR. THE TRACK FORECAST DURING THE EXTRATROPICAL PHASE IS A BLEND OF THE GFS...UKMET...AND ECMWF GLOBAL MODELS AND THE REVISED TRACK FORECAST IS SLIGHTLY SOUTH OF THE PREVIOUS ADVISORY. THE OCEAN PREDICTION CENTER PROVIDED POSITION...INTENSITY...AND SIZE GUIDANCE FOR THE EXTRATROPICAL PORTION OF DANIELLE. FORECAST POSITIONS AND MAX WINDS INITIAL 30/2100Z 41.3N 49.0W 60 KT 12HR VT 31/0600Z 42.0N 45.5W 55 KT...POST-TROP/EXTRATROP 24HR VT 31/1800Z 43.0N 38.0W 55 KT...POST-TROP/EXTRATROP 36HR VT 01/0600Z 45.5N 30.0W 50 KT...POST-TROP/EXTRATROP 48HR VT 01/1800Z 48.0N 23.0W 45 KT...POST-TROP/EXTRATROP 72HR VT 02/1800Z 55.5N 23.0W 40 KT...POST-TROP/EXTRATROP 96HR VT 03/1800Z...DISSIPATED $$ FORECASTER LANDSEA/BERG