429 
 WTNT41 KNHC 292046
 TCDAT1
 HURRICANE DANIELLE DISCUSSION NUMBER  34
 NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL   AL062010
 500 PM AST SUN AUG 29 2010
  
 DEEP CONVECTION AROUND DANIELLE HAS BECOME RATHER ASYMMETRIC WITH
 MOST OF THE COOL CLOUD TOPS OCCURRING IN THE CYCLONE'S NORTHERN
 SEMICIRCLE. CORRESPONDING...DVORAK CURRENT INTENSITY ESTIMATES FROM
 SAB AND TAFB ARE DROPPING WITH 3.5...OR 55 KT...AND 4.0...OR 65
 KT...RESPECTIVELY. FORTUNATELY...A FORTUITOUS ASCAT PASS WAS
 RECEIVED FROM 1404Z WHICH SHOWED SEVERAL BELIEVABLE HURRICANE 
 FORCE WIND VECTORS. A CIMSS AMSU INTENSITY ESTIMATE FROM A 1626Z
 NOAA-19 OVERPASS EVEN SUGGESTED CATEGORY TWO INTENSITY...THOUGH
 THIS APPEARS TO BE TOO HIGH. THE INITIAL INTENSITY IS SET AT 70 KT
 AS A BLEND OF THESE. DANIELLE CONTINUES TO EXHIBIT 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.
  
 DANIELLE CONTINUES TO ACCELERATE TOWARD THE NORTH-NORTHEAST WITH A
 CURRENT SPEED OF ABOUT 25 KT. THERE WAS CONCERN THAT WE WERE
 FOLLOWING A MID-LEVEL VORTEX RATHER THAN THE SURFACE CIRCULATION.
 HOWEVER...GEOSTATIONARY VISIBLE AND POLAR ORBITING MICROWAVE IMAGERY
 SUGGESTS THAT THE VORTEX IS STILL COHERENT VERTICALLY. DANIELLE
 SHOULD DECELERATE SOME AND TURN TOWARD THE EAST-NORTHEAST BY
 TOMORROW UNDER THE INFLUENCE OF A VIGOROUS SHORTWAVE TROUGH TO ITS
 NORTHWEST AND A SUBTROPICAL RIDGE TO ITS SOUTHEAST. MOST OF THE
 MODELS LOSE THE VORTEX IN ABOUT 48 HR WHEN THE SYSTEM BECOMES
 EXTRATROPICAL. THIS IS BECAUSE THERE IS A PROMINENT BAROCLINIC
 DEVELOPMENT JUST NORTH OF DANIELLE...WHICH MAY RESULT IN THE VORTEX
 FROM DANIELLE BECOMING ABSORBED AT THAT TIME. ASSUMING THAT 
 DANIELLE REMAINS THE PRIMARY CYCLONE AFTER EXTRATROPICAL
 TRANSITION...A TRACK FORECAST IS PROVIDED THROUGH 96 HR. THE
 FORECAST TRACK IS FASTER THAN THE PREVIOUS ADVISORY AND MODEL
 CONSENSUS FOR THE NEXT 24 HR BECAUSE OF THE FASTER INITIAL MOTION
 THAN ANTCIPATED...AND THEN SIMILAR TO BOTH THEREAFTER. UNTIL
 EXTRATROPICAL TRANSITION IN ABOUT TWO DAYS...DANIELLE SHOULD WEAKEN
 GRADUALLY DUE TO MODERATE VERTICAL SHEAR AND DECREASING SSTS UNDER
 ITS TRACK. THE OCEAN PREDICTION CENTER PROVIDED POSITION...
 INTENSITY...AND SIZE GUIDANCE FOR THE EXTRATROPICAL PORTION OF
 DANIELLE.
  
 THE 1404Z ASCAT PASS ALLOWED FOR A SLIGHT ENLARGEMENT OF THE
 34...50...AND 64 KT WIND RADII ESTIMATED FOR THE INITIAL TIME.
  
 FORECAST POSITIONS AND MAX WINDS
  
 INITIAL      29/2100Z 38.0N  54.5W    70 KT
  12HR VT     30/0600Z 40.1N  52.9W    65 KT
  24HR VT     30/1800Z 41.3N  50.2W    60 KT
  36HR VT     31/0600Z 42.3N  45.5W    55 KT
  48HR VT     31/1800Z 44.0N  39.0W    60 KT...POST-TROP/EXTRATROP
  72HR VT     01/1800Z 51.0N  30.0W    60 KT...POST-TROP/EXTRATROP
  96HR VT     02/1800Z 57.6N  32.5W    50 KT...POST-TROP/EXTRATROP
 120HR VT     03/1800Z...DISSIPATED
  
 $$
 FORECASTER LANDSEA/BERG