[Tropical] Tropical Cyclone Discussion

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WTNT41 KNHC 291501
TCDAT1
HURRICANE DANIELLE DISCUSSION NUMBER  33
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL   AL062010
1100 AM AST SUN AUG 29 2010

DANIELLE HAS BEEN GRADUALLY WEAKENING TODAY AS DEPICTED IN THE
GEOSTATIONARY AND POLAR ORBITING SATELLITE IMAGERY.  VISIBLE AND
MICROWAVE SATELLITE IMAGERY FROM THE 0948Z TRMM AND 0950Z SSMIS
SUGGEST THAT THE MID-LEVEL CENTER OF DANIELLE IS DISPLACED SOMEWHAT
NORTHEAST OF THE SURFACE CENTER. DVORAK CI NUMBERS ARE AT 4.5 FROM
TAFB...OR 77 KT...AND 4.0 FROM SAB...OR 65 KT. A 0830Z AMSU
INTENSITY ESTIMATE FROM CIMSS SUGGESTED SOMEWHAT HIGHER
WINDS...BASED UPON A WELL-DEFINED MID AND UPPER LEVEL WARM CORE.
THE INITIAL INTENSITY IS SET AT 75 KT AS A BLEND OF THESE.

DANIELLE IS MOVING A BIT FASTER...23 KT...TOWARD THE NORTHEAST THIS
MORNING UNDER THE INFLUENCE OF A VIGOROUS SHORTWAVE TROUGH TO ITS
NORTHWEST AND A SUBTROPICAL RIDGE TO ITS SOUTHEAST.  THE MODELS ARE
IN TIGHT AGREEMENT THROUGH 48 HOURS IN DEPICTING MOTION TOWARD THE
NORTHEAST AT A SLIGHTLY SLOWER SPEED.  THE FORECAST TRACK IS QUITE
SIMILAR TO THE MODEL CONSENSUS AND THE PREVIOUS ADVISORY EXCEPT FOR
THE 96 HR POINT. THAT FORECAST POSITION IS WEST OF THE PREVIOUS
ADVISORY BUT EAST OF THE MODEL CONSENSUS...WHICH SHOWS DANIELLE
MOVING NORTH-NORTHWESTWARD WHILE IN THE PROCESS OF IT BECOMING
ABSORBED.

DANIELLE IS CURRENTLY EXHIBITING SOME BAROCLINICITY WHICH IS
BEING MANIFEST THROUGH THE COLD AIR ADVECTION ON THE NORTH AND WEST
SIDE OF THE CYCLONE.  HOWEVER...AS THE SYSTEM MOVES NORTHEASTWARD
AND A SURFACE HIGH REMAINS NEARLY STATIONARY OVER THE MID-ATLANTIC
STATES...THE EXTRATROPICAL TRANSITION SHOULD BE DELAYED. DURING THE
NEXT DAY OR SO...DANIELLE SHOULD WEAKEN GRADUALLY DUE TO MODERATE
VERTICAL SHEAR AND DECREASING SSTS UNDER ITS TRACK. ALL DYNAMICAL
MODELS AGREE THAT A FULL EXTRATROPICAL TRANSITION WILL OCCUR IN
ABOUT TWO DAYS...AND ET IS INDICATED HERE AT 48 HOUR. AFTER THIS
TRANSITION...THE SYSTEM IS LIKELY TO REINTENSIFY SLIGHTLY AND
REMAIN A LARGE AND STRONG EXTRATROPICAL CYCLONE THROUGH 4 DAYS. THE
INTENSITY FORECAST IS SIMILAR TO THE PREVIOUS ADVISORY AND A BIT
HIGHER THAN THE CONSENSUS OF THE STATISTICAL AND HURRICANE MODEL
GUIDANCE...AS BAROCLINIC FORCING SHOULD MAINTAIN AT LEAST A HIGH
END TROPICAL STORM AS DEPICTED BY THE GLOBAL MODELS.  BY DAY
5...THE CYCLONE SHOULD BE ABSORBED BY ANOTHER EXTRATROPICAL CYCLONE
IN THE FAR NORTH ATLANTIC. THE OCEAN PREDICTION CENTER PROVIDED
POSITION...INTENSITY...AND SIZE GUIDANCE FOR THE EXTRATROPICAL
PORTION OF DANIELLE.


FORECAST POSITIONS AND MAX WINDS

INITIAL      29/1500Z 35.5N  55.5W    75 KT
 12HR VT     30/0000Z 38.0N  53.8W    70 KT
 24HR VT     30/1200Z 39.7N  51.9W    65 KT
 36HR VT     31/0000Z 40.9N  48.5W    60 KT
 48HR VT     31/1200Z 43.1N  42.3W    65 KT...POST-TROP/EXTRATROP
 72HR VT     01/1200Z 47.0N  34.0W    65 KT...POST-TROP/EXTRATROP
 96HR VT     02/1200Z 57.5N  34.0W    55 KT...POST-TROP/EXTRATROP
120HR VT     03/1200Z...DISSIPATED

$$
FORECASTER LANDSEA/BERG



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