[Tropical] Tropical Cyclone Discussion

[EMWIN Server]

WTNT44 KNHC 160230
TCDAT4
HURRICANE IRENE DISCUSSION NUMBER  46
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
11 PM EDT MON AUG 15 2005

THE CENTER HAS BEEN MOSTLY INDISTINCT ON SATELLITE IMAGERY THIS
EVENING...AND AN SSMI OVERPASS AT 23Z SHOWED THE EYEWALL HAS ERODED
SLIGHTLY COMPARED TO THIS MORNING.  HOWEVER...DVORAK INTENSITY
ESTIMATES ARE UNCHANGED AND I WILL LEAVE THE ADVISORY INTENSITY AT
80 KT.  THERE IS CURRENTLY NO OUTFLOW IN THE NORTHWEST QUADRANT AS
IRENE IS BEGINNING TO BE AFFECTED BY THE UPPER-LEVEL WESTERLIES.

BASED LARGELY ON THAT SSMI OVERPASS...THE INITIAL MOTION IS
ESTIMATED TO BE 085/12...FASTER THAN BEFORE...AND FASTER THAN
PREDICTED BY THE 18Z GUIDANCE MODELS.  IN ADDITION...MUCH OF THE
CURRENT GUIDANCE IS SIGNIFICANTLY SLOWER THAN THE PREVIOUS OFFICIAL
FORECAST.  GIVEN THE CURRENT ACCELERATION TREND...I WILL ONLY SLOW
THE PREVIOUS FORECAST A LITTLE BIT AND THE NEW FORECAST IS FAIRLY
CLOSE TO THE FSU SUPERENSEMBLE.  SHOULD IRENE TAKE A PATH FARTHER
SOUTH THAN EXPECTED...IT COULD MOVE QUITE A BIT SLOWER THAN
FORECAST.

IRENE STILL HAS ABOUT 36 HOURS OVER WARM WATER...BUT THE SHEAR IS
EXPECTED TO INCREASE BEFORE THEN.  THIS SHEAR SHOULD INDUCE A
WEAKENING TREND...AND INDEED THE MICROWAVE DATA SUGGEST THIS TREND
HAS ALREADY BEGUN.  WEAKENING WOULD LIKELY BE SLOWER THAN FORECAST
SHOULD IRENE TAKE A MORE SOUTHERLY TRACK.  COOLER WATERS AND AN
APPROACHING MID-LATITUDE TROUGH ARE EXPECTED TO RESULT IN AN
EXTRATROPICAL TRANSITION WITHIN ABOUT 48 HOURS.

FORECASTER FRANKLIN


FORECAST POSITIONS AND MAX WINDS

INITIAL      16/0300Z 36.6N  64.4W    80 KT
 12HR VT     16/1200Z 37.1N  62.4W    75 KT
 24HR VT     17/0000Z 38.2N  59.8W    65 KT
 36HR VT     17/1200Z 40.4N  56.3W    55 KT
 48HR VT     18/0000Z 43.5N  51.5W    50 KT...EXTRATROPICAL
 72HR VT     19/0000Z 52.0N  40.0W    45 KT...EXTRATROPICAL
 96HR VT     20/0000Z 58.0N  32.0W    40 KT...EXTRATROPICAL
120HR VT     21/0000Z...ABSORBED INTO EXTRATROPICAL LOW


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