Tropical Storm DANIELLE

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TROPICAL STORM DANIELLE DISCUSSION NUMBER   7
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL   AL062010
500 AM AST MON AUG 23 2010
 
DANIELLE HAS BEEN EXHIBITING A CLASSIC BURSTING PATTERN WITH CLOUD
TOP TEMPERATURES AS LOW AS -85C DURING THE PAST SEVERAL HOURS.
AMSR-E AND TRMM MICROWAVE IMAGERY FROM 0351 AND 0541 UTC...
RESPECTIVELY...CONTINUE TO INDICATE THAT THE CIRCULATION
CENTER LIES ON THE NORTHEAST EDGE OF THE CONVECTIVE CANOPY...
PERHAPS A LITTLE MORE UNDERNEATH THE MAIN CONVECTIVE MASS THAN
PREVIOUSLY NOTED.  THE BURSTING PATTERN AND THE PLACEMENT OF THE
SURFACE CENTER SUGGESTS THAT DANIELLE CONTINUES TO UNDERGO EASTERLY
VERTICAL WIND SHEAR BUT POSSIBLY NOT AS MUCH BEFORE.  DVORAK
INTENSITY ESTIMATES ARE 3.0 AND 4.0 FROM SAB AND TAFB...
RESPECTIVELY...AND 3-HOUR AVERAGE ADT VALUES ARE 3.4. USING A BLEND
OF THESE INTENSITY ESTIMATES...THE ADVISORY INTENSITY IS RAISED
CONSERVATIVELY TO 50 KT.
 
THE MICROWAVE IMAGERY AND RECENT SATELLITE FIXES SUGGEST A
MOTION TO THE LEFT AND FASTER THAN PREVIOUS ESTIMATES...300/12.
GLOBAL MODELS SHOW THE STORM ON THE WESTERN EDGE OF A SUBTROPICAL
RIDGE OVER THE EASTERN ATLANTIC WHICH SHOULD KEEP DANIELLE ON A
WEST-NORTHWESTERLY COURSE WITH SOME FURTHER INCREASE IN FORWARD
SPEED DURING THE NEXT 24 TO 48 HOURS.  THEREAFTER...THE GUIDANCE IS
IN GOOD AGREEMENT THAT THE CYCLONE WILL BEGIN TO ENCOUNTER A BREAK
IN THE SUBTROPICAL RIDGE BETWEEN 45-50W WHICH SHOULD BECOME MORE
PRONOUNCED AS A MID-LATITUDE TROUGH DIGS OVER THE CENTRAL ATLANTIC
IN A FEW DAYS. THESE EVENTS SHOULD CAUSE DANIELLE TO TURN MORE
NORTHWESTWARD AND DECELERATE.  TRACK MODEL SOLUTIONS ARE FAIRLY
TIGHTLY CLUSTERED AND HAVE SHIFTED EASTWARD FROM THE PREVIOUS
PACKAGE. THE OFFICIAL NHC TRACK FORECAST IS ADJUSTED EASTWARD AND
IS CLOSE TO...BUT NOT AS FAR EAST AS...THE MULTI-MODEL CONSENSUS.
 
THE EASTERLY VERTICAL WIND SHEAR THAT HAS BEEN AFFECTING DANIELLE
IS FORECAST TO DECREASE IN 12 TO 24 HOURS...WHEN THE CYCLONE
BECOMES EMBEDDED IN A GENERALLY UNIFORM LAYER OF EASTERLY FLOW. 
SINCE THE STORM WILL BE OVER 27-28C WATER TEMPERATURES AND IN A
LOWER SHEAR ENVIRONMENT...A PERIOD OF GREATER INTENSIFICATION IS
FORECAST DURING THE NEXT DAY OR TWO.  AFTER ABOUT 48 HOURS...
HOWEVER...THE GUIDANCE SHOWS THAT DANIELLE COULD BEGIN TO FEEL THE
EFFECTS OF SOUTHWESTERLY VERTICAL WIND SHEAR WHEN IT INTERACTS WITH
A MID-LATITUDE TROUGH OVER THE CENTRAL ATLANTIC.  THE OFFICIAL NHC
WIND SPEED FORECAST IS IN REASONABLE AGREEMENT WITH THE LATEST
STATISTICAL/DYNAMICAL INTENSITY GUIDANCE. 
 
FORECAST POSITIONS AND MAX WINDS
 
INITIAL      23/0900Z 14.8N  37.1W    50 KT
 12HR VT     23/1800Z 15.7N  39.1W    55 KT
 24HR VT     24/0600Z 16.9N  42.0W    65 KT
 36HR VT     24/1800Z 18.3N  44.9W    70 KT
 48HR VT     25/0600Z 19.9N  47.5W    75 KT
 72HR VT     26/0600Z 23.5N  51.5W    75 KT
 96HR VT     27/0600Z 26.5N  54.5W    80 KT
120HR VT     28/0600Z 29.0N  57.0W    85 KT
 
$$
FORECASTER KIMBERLAIN
 
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