Hurricane DANIELLE

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HURRICANE DANIELLE DISCUSSION NUMBER  36
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL   AL062010
500 AM AST MON AUG 30 2010
 
ONLY A SMALL AREA OF CONVECTION REMAINS IN THE NORTHWESTERN QUADRANT
AS DANIELLE CONTINUES TO MOVE OVER PROGRESSIVELY COOLER WATER
AND TRANSITIONS INTO AN EXTRATROPICAL CYCLONE. THE INITIAL INTENSITY
OF 65 KT IS BASED ON A BLEND OF A DVORAK CURRENT INTENSITY ESTIMATE
OF T3.0/45 KT FROM TAFB AND A 30/0449Z AMSU OVERPASS THAT INDICATED
DANIELLE STILL POSSESSED A MID-/UPPER-LEVEL WARM CORE SIMILAR TO
THAT OF AN EARLIER 29/2133Z AMSU OVERPASS THAT YIELDED AN INTENSITY
ESTIMATE OF 87 KT.
 
THE INITIAL MOTION ESTIMATE IS 040/15. THERE IS NO CHANGE TO THE
PREVIOUS FORECAST TRACK REASONING. DANIELLE HAS BEEN CAPTURED BY A
MID-/UPPER-LEVEL TROUGH AND IS EXPECTED TO MOVE NORTHEASTWARD TO
EAST-NORTHEASTWARD AT 15-20 KT FOR THE NEXT 48-72 HOURS. AFTER
THAT...A LARGER AND STRONGER TROUGH IS FORECAST TO MOVE OUT OF
NORTHEASTERN CANADA AND HELP TO ACCELERATE WHAT WILL BE
EXTRATROPICAL CYCLONE DANIELLE NORTH-NORTHEASTWARD AND THEN
NORTHWARD BY 96 HOURS. THE OFFICIAL FORECAST TRACK IS SIMILAR TO
THE PREVIOUS ADVISORY THROUGH 36 HOURS. AFTER THAT...THE TRACK IS 
A BLEND OF THE PREVIOUS FORECAST...GUIDANCE FROM THE OCEAN
PREDICTION CENTER...AND THE CONSENSUS MODELS.
 
DANIELLE SHOULD CONTINUE TO SLOWLY WEAKEN AND BECOME FULLY
EXTRATROPICAL WITHIN THE NEXT 12 HOURS OR SO AS THE CYCLONE MOVES
OVER COOLER WATER THAT WILL BE APPROACHING 20C. BY 72 HOURS...WHAT
WILL BE EXTRATROPICAL CYCLONE DANIELLE AT THAT TIME MAY STRENGTHEN
SOME AS BAROCLINIC ENERGY GETS DRAWN INTO THE SYSTEM FROM THE MUCH
LARGER MID-/UPPER-LEVEL TROUGH CURRENTLY PUSHING OUT OF
NORTHEASTERN CANADA. THE EX-DANIELLE CIRCULATION SHOULD REMAIN
LARGE AND FAIRLY STRONG OVER THE FAR NORTH ATLANTIC SHIPPING LANES.
 
MINOR ADJUSTMENTS WERE MADE TO THE ALREADY LARGE 34-KT WIND RADII
AND THE 12-FT SEAS RADII BASED ON A FEW SURROUNDING BUOY
OBSERVATIONS...AND ON 29/2344Z AND 30/0134 ASCAT WINDS.
 

FORECAST POSITIONS AND MAX WINDS
 
INITIAL      30/0900Z 40.4N  52.0W    65 KT
 12HR VT     30/1800Z 41.6N  49.3W    55 KT...POST-TROP/EXTRATROP
 24HR VT     31/0600Z 42.7N  44.3W    55 KT...POST-TROP/EXTRATROP
 36HR VT     31/1800Z 44.0N  38.0W    55 KT...POST-TROP/EXTRATROP
 48HR VT     01/0600Z 46.0N  32.0W    55 KT...POST-TROP/EXTRATROP
 72HR VT     02/0600Z 53.0N  26.0W    55 KT...POST-TROP/EXTRATROP
 96HR VT     03/0600Z 63.0N  32.0W    50 KT...POST-TROP/EXTRATROP
120HR VT     04/0600Z...DISSIPATED
 
$$
FORECASTER STEWART
 
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