Hurricane IGOR
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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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