Hurricane DANIELLE

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HURRICANE DANIELLE DISCUSSION NUMBER  20
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL   AL062010
1100 AM AST THU AUG 26 2010

DANIELLE HAS GONE THROUGH ANOTHER ROUND OF CHANGES IN ITS CONVECTIVE
STRUCTURE.  THE EYE THAT WAS APPARENT FROM 05-07Z DISAPPEARED AT
ABOUT 10Z...ACCOMPANIED BY AN OVERALL DECREASE IN ORGANIZATION. 
SINCE THEN...THE EYE HAS RE-APPEARED...EMBEDDED IN A RAGGED CENTRAL
DENSE OVERCAST.  SATELLITE INTENSITY ESTIMATES ARE 90 KT FROM TAFB
AND SAB...SO THAT REMAINS THE INITIAL INTENSITY.  HOWEVER...THIS MAY
BE SMOOTHING THROUGH SOME SHORT-TERM FLUCTUATIONS.  

THE INITIAL MOTION IS 320/13.  IN THE FIRST 48 HR OF THE FORECAST
PERIOD...DANIELLE SHOULD BE STEERED GENERALLY NORTHWESTWARD BY A
LOW/MID-LEVEL RIDGE PASSING TO THE NORTH AND NORTHEAST OF THE
HURRICANE.  AFTER THAT TIME...A LARGE MID/UPPER-LEVEL TROUGH MOVING
THROUGH THE NORTHEASTERN UNITED STATES AND THE CANADIAN MARITIMES
IS EXPECTED TO CAUSE DANIELLE TO TURN TOWARD THE NORTH AND THE
NORTHEAST.  THE GUIDANCE HAS MADE A MAJOR EASTWARD SHIFT SINCE THE
PREVIOUS ADVISORY...AND IT IS NOW IN GOOD AGREEMENT ON RECURVATURE
INTO THE WESTERLIES WITH AN INCREASE IN FORWARD SPEED AFTER 72 HR. 
THE NEW FORECAST TRACK WILL ALSO BE SHIFTED EASTWARD DURING THIS
PERIOD...BUT NOT AS MUCH AS THE GUIDANCE HAS SHIFTED.  THE NEW
FORECAST TRACK IS DOWN THE MIDDLE OF THE GUIDANCE ENVELOPE FOR THE
FIRST 48 HR...AND IS ALONG THE LEFT EDGE OF THE GUIDANCE ENVELOPE
FROM 72-120 HR.  ADDITIONAL EASTWARD ADJUSTMENTS OF THE FORECAST
TRACK MAY BE NECESSARY THIS AFTERNOON IF THE CURRENT TRENDS IN THE
GUIDANCE CONTINUE.

ANALYSES FROM CIMSS AT THE UNIVERSITY OF WISCONSIN SUGGEST THAT
DANIELLE IS EXPERIENCING ABOUT 10 KT OF SOUTHWESTERLY VERTICAL WIND
SHEAR.  THE HURRICANE SHOULD CONTINUE IN A LIGHT/MODERATE SHEAR
ENVIRONMENT FOR 48 HR OR SO BEFORE ENCOUNTERING STRONGER SHEAR
ASSOCIATED WITH THE UPPER-LEVEL TROUGH.  ALL INTENSITY GUIDANCE
FORECAST STRENGTHENING FOR 24-48 HR AND THE INTENSITY FORECAST
FOLLOWS THAT SCENARIO...WITH A PEAK INTENSITY OF 100 KT IN 24 HR. 
AFTER 48 HR...INCREASING SHEAR AND DECREASING SEA SURFACE
TEMPERATURES SHOULD CAUSE STEADY WEAKENING.
 
 
FORECAST POSITIONS AND MAX WINDS
 
INITIAL      26/1500Z 24.4N  55.9W    90 KT
 12HR VT     27/0000Z 25.3N  57.3W    95 KT
 24HR VT     27/1200Z 26.5N  59.1W   100 KT
 36HR VT     28/0000Z 27.8N  60.4W   100 KT
 48HR VT     28/1200Z 29.3N  61.2W   100 KT
 72HR VT     29/1200Z 33.0N  60.5W    95 KT
 96HR VT     30/1200Z 36.5N  58.5W    85 KT
120HR VT     31/1200Z 39.0N  55.0W    70 KT
 
$$
FORECASTER BEVEN
 
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