[Tropical] Tropical Cyclone Discussion

[EMWIN Server]

WTNT41 KNHC 210855
TCDAT1
HURRICANE IGOR DISCUSSION NUMBER  53
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL   AL112010
500 AM AST TUE SEP 21 2010

IGOR CONTINUES TO LOSE TROPICAL CYCLONE CHARACTERISTICS AS IT
BECOMES MORE INVOLVED WITH A BAROCLINIC ZONE.  HOWEVER...A SMALL
AREA OF CONVECTION HAS DEVELOPED NORTH OF THE CENTER...AND THE
CYCLONE HAS NOT YET DEVELOPED A WELL-DEFINED FRONTAL BOUNDARY SOUTH
OF THE CENTER.  THUS...IGOR IS AGAIN MAINTAINED AS A TROPICAL
CYCLONE.  EXTRATROPICAL TRANSITION IS LIKELY TO BE COMPLETE LATER
TODAY...WITH SOME BAROCLINICALLY-INDUCED STRENGTHENING EXPECTED.
LATE IN THE FORECAST PERIOD...THE SYSTEM WILL BE MERGING WITH
ANOTHER EXTRATROPICAL LOW OVER HIGH LATITUDES.

THE INITIAL MOTION IS 045/36.  IGOR...OR THE EXTRATROPICAL LOW IT IS
FORECAST TO BECOME...IS LIKELY TO BE STEERED AROUND A LARGE
MID-LEVEL CYCLONIC GYRE OVER NORTHEASTERN NORTH AMERICA OVER THE
NEXT FEW DAYS.  THE NEW FORECAST TRACK IS SIMILAR TO THE PREVIOUS
FORECAST THROUGH 48 HR...THEN ADJUSTED SOMEWHAT TO THE SOUTH
THEREAFTER DURING THE FORECAST NORTHWESTWARD MOTION AT 72-96 HR.

EVEN THOUGH IGOR IS FORECAST TO BE EXTRATROPICAL AS IT PASSES
NEWFOUNDLAND...TROPICAL-STORM AND POSSIBLY HURRICANE-FORCE WINDS
COULD REACH THE COAST OF NEWFOUNDLAND BEFORE THE TRANSITION IS
COMPLETE.  ENVIRONMENT CANADA HAS ISSUED A HURRICANE WATCH AND
EXTENDED THE TROPICAL STORM WARNING FOR THE EASTERN PART OF THAT
PROVINCE.

FORECAST POSITIONS AND MAX WINDS

INITIAL      21/0900Z 42.8N  55.1W    65 KT
 12HR VT     21/1800Z 46.7N  51.3W    70 KT...POST-TROP/EXTRATROP
 24HR VT     22/0600Z 52.3N  48.4W    75 KT...POST-TROP/EXTRATROP
 36HR VT     22/1800Z 56.7N  48.3W    65 KT...POST-TROP/EXTRATROP
 48HR VT     23/0600Z 60.5N  52.5W    65 KT...POST-TROP/EXTRATROP
 72HR VT     24/0600Z 62.5N  59.0W    45 KT...POST-TROP/EXTRATROP
 96HR VT     25/0600Z 64.0N  61.0W    35 KT...POST-TROP/EXTRATROP
120HR VT     26/0600Z...DISSIPATED

$$
FORECASTER BEVEN


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