Hurricane DANIELLE

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HURRICANE DANIELLE DISCUSSION NUMBER  18
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL   AL062010
1100 PM AST WED AUG 25 2010
 
SATELLITE IMAGES INDICATE THAT DANIELLE HAS BECOME BETTER ORGANIZED
DURING THE PAST SEVERAL HOURS. A LARGE CURVED BAND FEATURE EXTENDS
AROUND THE HURRICANE...AND THE CENTRAL DENSE OVERCAST HAS BECOME
MORE CIRCULAR WITH SIGNS OF A RAGGED EYE. MICROWAVE PASSES FROM
2000-2200 UTC CONFIRM THIS TREND AND SHOW THE DEVELOPMENT OF AN
EYEWALL THAT IS MOSTLY CLOSED. THE INITIAL WIND SPEED IS RAISED TO
85 KT...AND IS A BLEND OF THE CI NUMBERS FROM TAFB/SAB. THE SIZE OF
THE HURRICANE APPEARS TO BE EXPANDING ON SATELLITE...AND WIND
ANALYSES FROM CSU/CIRA ALSO SHOW THIS GROWTH. BASED ON THE ABOVE
DATA...THE INITIAL AND FORECAST WIND RADII HAVE BEEN INCREASED.
 
IT IS A LITTLE SURPRISING THAT THE HURRICANE HAS BEEN INTENSIFYING
AS WIND SHEAR ANALYSES FROM UW-CIMSS SHOW ABOUT 15 KT OF
SOUTHWESTERLY SHEAR.  THIS SHEAR IS FORECAST TO ABATE BY LATE
TOMORROW AS AN UPPER-LEVEL LOW DROPS TO THE SOUTHWEST OF DANIELLE. 
THIS IS A COMMON SYNOPTIC SITUATION THAT SUPPORTS INTENSIFICATION
AND NOW MOST OF THE GUIDANCE HAVE DANIELLE NEAR MAJOR HURRICANE
STRENGTH ON FRIDAY.  BY THE END OF THE PERIOD...THE HURRICANE
SHOULD BE WEAKENING AS IT ENCOUNTERS COOLER WATER AND AN INCREASE
IN SHEAR.  THIS SCENARIO IS FOLLOWED IN THE OFFICIAL FORECAST...AND
THE FORECAST INTENSITY IS A LITTLE HIGHER THAN THE PREVIOUS ONE.   
 
THE INITIAL MOTION IS ABOUT 320/15 DURING THE PAST 12 HOURS...AND
EVEN A LITTLE TO THE RIGHT OF THAT RECENTLY.  A LARGE TROUGH TO THE
NORTH OF THE HURRICANE HAS APPARENTLY BEEN CAUSING IT TO MOVE A
LITTLE TO THE RIGHT OF THE FORECAST PATH...BUT THE TROUGH IS
RAPIDLY MOVING AWAY FROM DANIELLE.  THIS SHOULD ALLOW A RIDGE TO
REBUILD TO THE NORTH OF THE HURRICANE AND A LEFTWARD BEND OF THE
TRACK BY TOMORROW NIGHT. IN A FEW DAYS...A TURN TO THE NORTH IS
ANTICIPATED AS THE CYCLONE MOVES BETWEEN A RIDGE OVER THE CENTRAL
ATLANTIC AND AN UPPER TROUGH OVER THE WESTERN ATLANTIC. GUIDANCE
REMAINS DIVERGENT ON WHETHER THE HURRICANE WILL SIMPLY RECURVE OUT
TO SEA WITH THAT TROUGH...OR WHETHER IT WILL BE LEFT BEHIND AND
RESUME A SLOWER MOTION TO THE NORTHWEST OR NORTH. THE MOST RELIABLE
MODELS ARE GENERALLY NEAR OR EAST OF THE MODEL CONSENSUS...AND THE
OFFICIAL TRACK FORECAST WILL LEAN ON THAT SIDE OF THE GUIDANCE
ENVELOPE...SLIGHTLY TO THE EAST OF THE PREVIOUS NHC TRACK.
  
 
FORECAST POSITIONS AND MAX WINDS
 
INITIAL      26/0300Z 22.4N  54.1W    85 KT
 12HR VT     26/1200Z 23.7N  55.6W    90 KT
 24HR VT     27/0000Z 25.0N  57.4W    95 KT
 36HR VT     27/1200Z 26.1N  59.3W   100 KT
 48HR VT     28/0000Z 27.5N  60.8W   100 KT
 72HR VT     29/0000Z 30.3N  62.3W   100 KT
 96HR VT     30/0000Z 33.5N  62.0W    90 KT
120HR VT     31/0000Z 37.0N  61.5W    80 KT
 
$$
FORECASTER BLAKE
 
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