Hurricane IGOR

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HURRICANE IGOR DISCUSSION NUMBER  51
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL   AL112010
500 PM AST MON SEP 20 2010
 
IGOR APPEARS TO BE STARTING EXTRATROPICAL TRANSITION.  SURFACE
OBSERVATIONS INDICATE THAT A FRONTAL BOUNDARY EXTENDS FROM
NEWFOUNDLAND SOUTHWARD TOWARDS THE HURRICANE...AND COLD ADVECTION
IS INCREASING OVER THE WESTERN SIDE OF ITS CIRCULATION.  GLOBAL
MODEL FIELDS SUGGEST THAT IGOR SHOULD BE FULLY INCORPORATED INTO
THE FRONTAL ZONE BY 24 HOURS...IF NOT SOONER.  ASCAT DATA FROM
EARLIER THIS MORNING SHOWED A LARGE AREA OF STRONG WINDS...
BETWEEN 55-64 KT...OVER THE SOUTHWESTERN QUADRANT OF THE STORM AND
SUPPORTS AN INITIAL INTENSITY OF 65 KT.  THE ORIENTATION OF THE
STRONG WINDS OVER THE SOUTHWESTERN QUADRANT ALSO SUGGESTS THAT
EXTRATROPICAL TRANSITION IS OCCURRING.  IGOR COULD BE REINVIGORATED
DURING THE NEXT 24 HOURS AS IT BECOMES EXTRATROPICAL...AND THE NHC
FORECAST CONTINUES TO SHOW SOME STRENGTHENING IN THE SHORT TERM...
FOLLOWED BY GRADUAL WEAKENING AND DISSIPATION BY 120 HOURS.
 
THE INITIAL MOTION IS NOW 040/24.  THE TRACK GUIDANCE IS STILL
TIGHTLY CLUSTERED FOR THE NEXT 24 HOURS AND THEN SHOWS INCREASING
SPREAD AFTER THAT TIME.  THERE IS GREATER AGREEMENT THAT IGOR WILL
TURN NORTHWARD AND THEN NORTHWESTWARD TOWARD GREENLAND AFTER 24
HOURS...BUT THERE IS NOT AS MUCH AGREEMENT IN THE FORWARD SPEED. 
THE NEW TRACK FORECAST IS A BLEND OF THE PREVIOUS FORECAST...THE
MODEL CONSENSUS TVCN...AND GUIDANCE PROVIDED BY THE OCEAN
PREDICTION CENTER.
 
EVEN THOUGH IGOR IS FORECAST TO BE EXTRATROPICAL AS IT PASSES
NEWFOUNDLAND...TROPICAL STORM FORCE WINDS COULD REACH THE COAST OF
NEWFOUNDLAND BEFORE THE TRANSITION IS COMPLETE.  THEREFORE...
ENVIRONMENT CANADA HAS ISSUED A TROPICAL STORM WARNING FOR THE
EASTERN PART OF THAT PROVINCE.
 
FORECAST POSITIONS AND MAX WINDS
 
INITIAL      20/2100Z 38.2N  61.5W    65 KT
 12HR VT     21/0600Z 41.0N  57.9W    70 KT
 24HR VT     21/1800Z 45.3N  52.3W    75 KT...POST-TROP/EXTRATROP
 36HR VT     22/0600Z 50.1N  47.5W    70 KT...POST-TROP/EXTRATROP
 48HR VT     22/1800Z 54.6N  45.8W    60 KT...POST-TROP/EXTRATROP
 72HR VT     23/1800Z 60.0N  46.5W    50 KT...POST-TROP/EXTRATROP
 96HR VT     24/1800Z 66.0N  56.0W    30 KT...POST-TROP/EXTRATROP
120HR VT     25/1800Z...DISSIPATED
 
$$
FORECASTER BERG
 
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