Hurricane DANIELLE

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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
 
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