WTNT44 KNHC 180823                                              2005230 0823
TCDAT4
TROPICAL STORM IRENE DISCUSSION NUMBER  55
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
5 AM EDT THU AUG 18 2005

IRENE HAS BEEN ACCELERATING RAPIDLY NORTHEASTWARD THE PAST 6 HOURS
NOW THAT THE CYCLONE IS FULLY CAUGHT UP IN THE DEEP SOUTHWESTERLY
FLOW AHEAD OF AN APPROACHING STRONG MID-LATITUDE EXTRATROPICAL
CYCLONE AND ASSOCIATED FRONTAL SYSTEM. SATELLITE INTENSITY
ESTIMATES FROM TAFB AND SAB ARE 45 KT AND 55 KT...RESPECTIVELY.
HOWEVER...GIVEN THE FASTER FORWARD SPEED...I HAVE OPTED TO MAINTAIN
THE INTENSITY AT 60 KT FOR THIS ADVISORY.

THE INITIAL MOTION ESTIMATE IS 045/30. THE INITIAL POSITION IS BASED
ON CONTINUITY WITH THE PREVIOUS FORECAST TRACK AND EXTRAPOLATION
FROM SEVERAL MICROWAVE SATELLITE POSITION ESTIMATES BETWEEN 17/21Z
AND 18/02Z. IRENE SHOULD CONTINUE TO ACCELERATE NORTHEASTWARD AT
FORWARD SPEEDS OF 35-40 KT...OR HIGHER...THROUGHOUT THE REMAINDER
OF THE FORECAST. THIS WILL TAKE THE CYCLONE OVER MUCH COLDER WATER
WITHIN THE NEXT FEW HOURS...WHICH SHOULD RESULT IN A RAPID
TRANSITION OVER TO A POWERFUL EXTRATROPICAL LOW PRESSURE SYSTEM.

FORECASTER STEWART
FORECAST POSITIONS AND MAX WINDS

INITIAL      18/0900Z 41.3N  51.0W    60 KT...BECOMING EXTRATROPICAL
 12HR VT     18/1800Z 46.0N  46.1W    55 KT...EXTRATROPICAL
 24HR VT     19/0600Z 54.0N  40.0W    50 KT...EXTRATROPICAL
 36HR VT     19/1800Z...ABSORBED BY LARGER EXTRATROPICAL LOW


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