Hurricane DANIELLE

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HURRICANE DANIELLE DISCUSSION NUMBER  11
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL   AL062010
500 AM AST TUE AUG 24 2010
 
ALTHOUGH THE CLOUD PATTERN ASSOCIATED WITH DANIELLE IS NOT AS WELL
ORGANIZED AS IT WAS SEVERAL HOURS AGO...LATEST DVORAK SATELLITE
INTENSITY ESTIMATES FROM SAB AND TAFB ARE AT 77 AND 90 KT...
RESPECTIVELY. THE CONVECTIVE ORGANIZATION OF THE CYCLONE HAS BEEN
PULSATING FOR REASONS THAT ARE NOT WELL UNDERSTOOD...BUT THE
OVERALL TREND IS INDICATIVE OF A GENERAL INTENSIFICATION. UPPER-
LEVEL OUTFLOW IS WELL ESTABLISHED OVER THE EASTERN SEMICIRCLE BUT
IS LESS DEFINED TO THE WEST. BASED UPON THE HIGHER SATELLITE
INTENSITY ESTIMATES...THE ADVISORY INTENSITY IS INCREASED TO 85 KT.

AN EYE FEATURE THAT FORMED EARLIER IS NO LONGER EVIDENT...BUT A 0434
UTC AMSR-E OVERPASS WAS HELPFUL IN LOCATING THE CENTER.  THAT
OVERPASS AND OTHER RECENT FIXES YIELD AN INITIAL MOTION SLIGHTLY TO
THE LEFT OF THE PREVIOUS ESTIMATE...280/17.  DANIELLE IS EXPECTED
TO MOVE ON A GENERAL WEST-NORTHWESTWARD COURSE FOR THE NEXT 12
HOURS OR SO BUT IS FORECAST TO GRADUALLY TURN MORE TOWARD THE
NORTHWEST WHEN IT BEGINS TO ENCOUNTER A WEAKNESS IN THE SUBTROPICAL
RIDGE APPARENT IN WATER VAPOR IMAGERY BETWEEN 45-50W.  DYNAMICAL
MODEL GUIDANCE SHOWS THE BREAK IN THE RIDGE BECOMING MORE
PRONOUNCED BY 48 HOURS WHEN A STRONGER MID-LATITUDE TROUGH
AMPLIFIES OVER THE CENTRAL ATLANTIC.  THE EVOLUTION OF THESE
FEATURES SHOULD CAUSE DANIELLE TO DECELERATE AND TURN NORTH-
NORTHWESTWARD LATER IN THE FORECAST PERIOD.  THE OFFICIAL NHC TRACK
FORECAST IS ESSENTIALLY AN UPDATE OF THE PREVIOUS PACKAGE AND LIES
CLOSE TO THE MULTI-MODEL CONSENSUS.

GLOBAL MODELS SHOW DANIELLE REMAINING IN A LOW VERTICAL WIND SHEAR
ENVIRONMENT FOR THE NEXT 24 HOURS OVER WATER TEMPERATURES BETWEEN
28-29C.  THESE FAVORABLE FACTORS SHOULD LEAD TO A CONTINUED
INTENSIFICATION OF THE CYCLONE...AND THE SHIPS RI INDEX INDICATES A
35% CHANCE OF AN INCREASE IN INTENSITY OF 25 KT DURING THE NEXT 24
HOURS.  BETWEEN 24-72 HOURS...SOME INCREASE IN SOUTHWESTERLY
VERTICAL WIND SHEAR ASSOCIATED WITH AN UPPER-LEVEL TROUGH MOVING
SOUTHWESTWARD OVER THE CENTRAL ATLANTIC COULD HALT THE CURRENT
INTENSIFICATION OR POSSIBLY RESULT IN SOME WEAKENING.  LATER IN THE
PERIOD...THE NUMERICAL GUIDANCE SUGGESTS SOME SLIGHT REDUCTION IN
SHEAR...BUT...GIVEN THE UNCERTAINTIES...THE OFFICIAL FORECAST DOES
NOT SHOW RESTRENGTHENING IN 3-5 DAYS.  THE OFFICIAL NHC WIND SPEED
FORECAST IS SIMILAR TO BUT SLIGHTLY HIGHER THAN THE PREVIOUS ONE
DURING THE FIRST 24 HOURS...AND UNCHANGED BEYOND THAT TIME.
  
FORECAST POSITIONS AND MAX WINDS
 
INITIAL      24/0900Z 15.9N  44.6W    85 KT
 12HR VT     24/1800Z 16.9N  46.6W    95 KT
 24HR VT     25/0600Z 18.6N  48.9W   105 KT
 36HR VT     25/1800Z 20.5N  51.0W   100 KT
 48HR VT     26/0600Z 22.3N  52.9W   100 KT
 72HR VT     27/0600Z 25.5N  55.5W    95 KT
 96HR VT     28/0600Z 28.0N  57.5W    95 KT
120HR VT     29/0600Z 31.5N  59.0W    95 KT
 
$$
FORECASTER KIMBERLAIN
 
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