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Hurricane IGOR (Text)

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HURRICANE IGOR DISCUSSION NUMBER  38...CORRECTED
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL   AL112010
1100 AM AST FRI SEP 17 2010

CORRECT SAB SATELLITE CLASSIFICATION
 
THE OVERALL CLOUD PATTERN OF IGOR HAS CHANGED LITTLE IN ORGANIZATION
OVER THE PAST SEVERAL HOURS...ALTHOUGH DVORAK CI NUMBERS HAVE
DECREASED TO 5.5 FROM SAB AND TAFB...RESPECTIVELY.  BASED UPON THESE
DATA...THE INITIAL WIND SPEED IS LOWERED TO 105 KT. AN 0915 UTC
SSMIS OVERPASS SHOWED THE EXISTENCE OF A NEW OUTER WIND MAXIMUM AT
ABOUT 90 NMI RADIUS...WITH AN INNER EYEWALL PARTIALLY BROKEN TO THE
WEST.  INNER CORE DYNAMICS ASIDE...THERE IS STILL AN  OPPORTUNITY
FOR RE-INTENSIFICATION DURING THE NEXT DAY OR TWO WHILE IGOR IS
LOCATED IN A LIGHT SHEAR ENVIRONMENT AND MOVING OVER WARM WATERS. 
GLOBAL MODELS FORECAST A GRADUAL INCREASE IN SOUTHERLY TO
SOUTHWESTERLY SHEAR OVER THE CYCLONE AFTER ABOUT 48 HOURS AND
WATERS GRADUALLY BECOME COOLER AFTER THAT.  BOTH OF THESE FACTORS
SUGGEST A SLOW WEAKENING OF IGOR BEGINNING AFTER ABOUT TWO
DAYS...AND THE OFFICIAL NHC FORECAST IS ABOUT THE SAME AS BEFORE.
THE GUIDANCE SUGGESTS THAT EXTRATROPICAL TRANSITION SHOULD BE
COMPLETED BETWEEN 96 AND 120 HOURS.
 
IGOR IS MAINTAINING A FAIRLY STEADY MOTION OF 305/08.  THE STEERING
FLOW AROUND THE SOUTHWEST SIDE OF A SUBTROPICAL RIDGE SHOULD GUIDE
IGOR ON A NORTHWESTWARD AND THEN NORTH-NORTHWESTWARD COURSE DURING
THE NEXT COUPLE OF DAYS.  AFTER THAT...THE APPROACH OF A VIGOROUS
SHORTWAVE TROUGH OVER THE NORTHEASTERN U.S. SHOULD GRADUALLY TURN
THE HURRICANE NORTHWARD AND THEN NORTHEASTWARD WITH A SUBSTANTIAL
INCREASE IN FORWARD SPEED.  THE OFFICIAL NHC TRACK FORECAST IS CLOSE
TO THE PREVIOUS ONE...EXCEPT FOR BEING SOMEWHAT SLOWER AT
96 AND 120 HOURS IN LINE WITH THE LATEST GUIDANCE.
  
 
FORECAST POSITIONS AND MAX WINDS
 
INITIAL      17/1500Z 23.1N  60.1W   105 KT
 12HR VT     18/0000Z 24.0N  61.5W   105 KT
 24HR VT     18/1200Z 25.4N  63.2W   105 KT
 36HR VT     19/0000Z 27.0N  64.5W   100 KT
 48HR VT     19/1200Z 28.8N  65.1W   100 KT
 72HR VT     20/1200Z 34.0N  63.5W    90 KT
 96HR VT     21/1200Z 41.0N  55.0W    75 KT...POST-TROP/EXTRATROP
120HR VT     22/1200Z 51.0N  44.5W    60 KT...POST-TROP/EXTRATROP
 
$$
FORECASTER KIMBERLAIN
 
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