Tropical Storm DANIELLE

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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
 
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FORECASTER LANDSEA/BERG
 
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