Tropical Storm DANNY

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TROPICAL STORM DANNY DISCUSSION NUMBER   5
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL   AL052009
1100 AM EDT THU AUG 27 2009
 
DANNY HAS BECOME A LITTLE BETTER ORGANIZED THIS MORNING.  THE
LOW-LEVEL CIRCULATION LOOKS BETTER DEFINED THAN IT DID YESTERDAY...
AND THE CONVECTION IS CLOSER TO THE CENTER.  THAT BEING SAID...THE
CENTER IS STILL EXPOSED...THE CONVECTION HAS MORE OF A LINEAR
CHARACTER THAN THE CURVED BANDS CHARACTERISTIC OF A TROPICAL
CYCLONE...AND THE STRONGEST WINDS ARE STILL WELL REMOVED FROM THE
CENTER.  THE INITIAL INTENSITY IS HELD AT 50 KT PENDING THE NEXT
AIR FORCE RESERVE HURRICANE HUNTER MISSION AT 18Z...ALTHOUGH RECENT
QUIKSCAT DATA SUGGESTS THIS COULD BE A LITTLE GENEROUS.
 
THE EXPOSED LOW-LEVEL CENTER HAS BEEN MOVING ALMOST DUE WESTWARD FOR
THE PAST FEW HOURS.  IT IS UNCLEAR IF THIS IS REPRESENTATIVE OF THE
ACTUAL MOTION OF DANNY OR A SHORT-TERM TREND.  SO...THE INITIAL
MOTION IS AN UNCERTAIN 310/11.  DESPITE THE PROBLEMATIC INITIAL
MOTION...THE TRACK GUIDANCE MODELS ARE IN EXCELLENT AGREEMENT THAT
DANNY SHOULD TURN NORTHWARD OVER THE NEXT 24-36 HR IN ADVANCE OF A
COMPLEX DEEP-LAYER TROUGH MOVING INTO THE EASTERN UNITED STATES.
AFTER THAT...THE STORM SHOULD ACCELERATE NORTHEASTWARD INTO THE
WESTERLIES...PASSING NEAR OR OVER NEW ENGLAND AND THE CANADIAN
MARITIMES ON ITS WAY INTO THE NORTH ATLANTIC.  THE
NAM...NOGAPS...AND CANADIAN MODELS ARE ON THE LEFT SIDE OF THE
GUIDANCE ENVELOPE... CALLING FOR THE CENTER TO PASS NEAR CAPE
HATTERAS AND THEN OVER NEW ENGLAND.  THE GFS...GFDL...AND HWRF ARE
ON THE RIGHT SIDE...CALLING FOR THE CENTER TO STAY OFFSHORE UNTIL
IT REACHES NOVA SCOTIA.  THE NEW FORECAST TRACK IS ADJUSTED TO THE
LEFT OF THE PREVIOUS TRACK FOR THE FIRST 48 HR BASED ON THE INITIAL
POSITION AND MOTION...AND IT LIES DOWN THE MIDDLE OF THE GUIDANCE
ENVELOPE.  WHILE THE FORECAST TRACK DOES NOT CURRENTLY SHOW DANNY
MAKING LANDFALL IN THE UNITED STATES...ADDITIONAL MOTION TO THE
LEFT OF THE TRACK COULD BRING THE CENTER NEAR OR OVER THE U. S.
EASTERN SEABOARD.
 
DANNY IS CURRENTLY IN AN AREA OF UPPER-LEVEL CONFLUENT FLOW
ASSOCIATED WITH THE PERSISTENT CYCLONIC SHEAR AXIS SEEN IN WATER
VAPOR IMAGERY.  THE LARGE-SCALE MODELS FORECAST THIS FEATURE TO BE
REPLACED BY AN UPPER-LEVEL ANTICYCLONE DURING THE NEXT 24-30 HR...
AND IF THIS VERIFIES IT WILL GIVE DANNY ITS BEST CHANCE TO
STRENGTHEN.  BASED ON THIS...THE INTENSITY FORECAST CALLS FOR DANNY
TO STRENGTHEN DURING THE 24-48 HR PERIOD...WITH A PEAK INTENSITY OF
65 KT.  THE GUIDANCE AGREES THAT DANNY SHOULD START LOSING TROPICAL
CHARACTERISTICS AND INTENSITY AFTER 48 HR AS IT BECOMES EMBEDDED IN
A STRONG BAROCLINIC ENVIRONMENT.  OVERALL...THE INTENSITY FORECAST
IS IN BEST AGREEMENT WITH THE INTENSITY CONSENSUS...WITH THE PEAK
INTENSITY BELOW THAT OF THE HWRF AND GFDL MODELS.
 
 
FORECAST POSITIONS AND MAX WINDS
 
INITIAL      27/1500Z 27.5N  73.1W    50 KT
 12HR VT     28/0000Z 28.7N  73.9W    50 KT
 24HR VT     28/1200Z 30.3N  74.5W    55 KT
 36HR VT     29/0000Z 33.2N  74.3W    60 KT
 48HR VT     29/1200Z 36.9N  72.4W    65 KT
 72HR VT     30/1200Z 45.0N  64.5W    60 KT...EXTRATROPICAL
 96HR VT     31/1200Z 50.0N  53.0W    45 KT...EXTRATROPICAL
120HR VT     01/1200Z 52.5N  37.0W    30 KT...EXTRATROPICAL
 
$$
FORECASTER BEVEN
 
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