[Tropical] Tropical Cyclone Discussion

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WTNT43 KNHC 010231
TCDAT3
TROPICAL STORM LISA DISCUSSION NUMBER  47
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
11 PM EDT THU SEP 30 2004

CONVENTIONAL AND MICROWAVE SATELLITE IMAGERY INDICATE THAT LIKELY
HAS REMAINED JUST BELOW HURRICANE STRENGTH. A CLOSED LOW-LEVEL EYE
FEATURE WAS APPARENT IN 30/2101Z TRMM AND 01/0020Z SSMI OVERPASSES
...AND A BANDING EYE FEATURE HAS BEEN TRYING TO DEVELOP IN VISIBLE
AND INFRARED IMAGERY FOR THE PAST 9 HOURS. IN ADDITION...A 30/2117Z
UW-CIMSS AMSU OVERPASS INDICATED A PRESSURE ESTIMATE OF 989.6 MB.
THEREFORE...THE PRESSURE AND INTENSITY WILL REMAIN THE SAME AT 990
MB AND 60 KT...RESPECTIVELY...AS IN THE PREVIOUS ADVISORY.

THE INITIAL MOTION ESTIMATE IS 005/10. THE LAST 9 HOURS OF
CONVENTIONAL AND MICROWAVE SATELLITE FIX POSITIONS INDICATE THAT
LISA HAS MADE THE TURN TOWARD THE NORTH. A GRADUAL TURN TOWARD THE
NORTH-NORTHEAST AND EVENTUALLY TO THE NORTHEAST IS EXPECTED TO
OCCUR IN THE 12-24 TIME PERIOD AS AN APPROACHING SHORTWAVE PICKS UP
THE CYCLONE. BY 36 HOURS...LISA IS EXPECTED TO ACCELERATE AS THE
CYCLONE BEGINS TO TRANSITION OVER TO AN EXTRATROPICAL LOW...OR
POSSIBLY BECOME ABSORBED BY A LARGER EXTRATROPICAL CYCLONE.

LISA IS EXPECTED TO REMAIN IN FAVORABLE VERTICAL SHEAR CONDITIONS OF
5-10 KT FOR THE NEXT 24 HOURS...EVEN THOUGH THE CYCLONE WILL BE
MOVING OVER 24-25C SSTS. AS MENTIONED IN THE PREVIOUS
DISCUSSION...ENOUGH MODERATE CONVECTION MAY WRAP AROUND THE CENTER
LATER TONIGHT TO FINALLY CLOSE OFF AN EYE IN THE MID- AND
UPPER-LEVELS...ALLOWING LISA TO REACH MINIMAL HURRICANE STRENGTH.
AFTER 24 HOURS...INCREASING WESTERLY VERTICAL SHEAR AND MUCH COOLER
WATER SHOULD BRING ABOUT A WEAKENING TREND. THE OFFICIAL FORECAST
IS A LITTLE LOWER THAN THE SHIPS AND GFDL INTENSITY MODELS WHICH
BRING LISA TO 63 KT AND 69 KT IN 24 HOURS...RESPECTIVELY.

FORECASTER STEWART

FORECAST POSITIONS AND MAX WINDS

INITIAL      01/0300Z 34.6N  47.7W    60 KT
 12HR VT     01/1200Z 36.3N  47.3W    60 KT
 24HR VT     02/0000Z 39.0N  44.8W    55 KT
 36HR VT     02/1200Z 42.2N  40.4W    45 KT...BECOMING EXTRATROPICAL
 48HR VT     03/0000Z 45.0N  33.0W    35 KT...EXTRATROPICAL
 72HR VT     04/0000Z...ABSORBED BY EXTRATROPICAL LOW


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