[Tropical] Tropical Cyclone Discussion

[EMWIN Server]

WTNT43 KNHC 232046
TCDAT3
TROPICAL DEPRESSION LISA DISCUSSION NUMBER  18
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
5 PM EDT THU SEP 23 2004

VISIBLE SATELLITE IMAGERY SHOWS THAT NORTHERLY SHEAR HAS BLOWN AWAY
THE DEEP CONVECTION AND EXPOSED A LOW LEVEL CLOUD CENTER TO THE
NORTHEAST OF WHERE A CENTER LOCATION WAS ESTIMATED ON THE PREVIOUS
ADVISORY.  THIS REQUIRES A RELOCATION OF THE CENTER AND IMPLIES
THAT THE CENTER HAS MOVED IN A CYCLONIC OOP OVER THE PAST 24 HOURS
AND IS NOW MOVING ABOUT 300/05.  THE GLOBAL TRACK MODELS ARE IN
GOOD AGREEMENT ABOUT A SLOW MOSTLY NORTH-NORTHWESTWARD MOTION
TOWARD A WEAKNESS IN THE SUBTROPICAL RIDGE TO THE NORTH OF LISA.
THE OFFICIAL TRACK FORECAST FOLLOWS A CONSENSUS OF THE GUIDANCE AND
IS ADJUSTED TO THE RIGHT OF THE PREVIOUS ADVISORY DUE TO THE
RELOCATION.

THE ABSENCE OF ANY DEEP CONVECTION NEAR THE CENTER IS GROUNDS FOR
DOWNGRADING LISA TO A TROPICAL DEPRESSION.  THE SHIPS MODEL
INDICATES THAT THE VERTICAL SHEAR WILL WEAKEN SOME OVER THE NEXT 72
HOURS AND THE OFFICIAL FORECAST IS FOR MODEST INTENSIFICATION
THROUGH 72 HOURS...A LITTLE MORE THAN SHIPS BUT NOT NEARLY AS
AGGRESSIVE AS THE GFDL MODEL.

FORECASTER LAWRENCE

FORECAST POSITIONS AND MAX WINDS

INITIAL      23/2100Z 14.3N  40.7W    30 KT
 12HR VT     24/0600Z 14.4N  41.0W    30 KT
 24HR VT     24/1800Z 14.9N  41.9W    30 KT
 36HR VT     25/0600Z 16.0N  43.1W    35 KT
 48HR VT     25/1800Z 17.3N  44.1W    45 KT
 72HR VT     26/1800Z 20.2N  45.2W    55 KT
 96HR VT     27/1800Z 23.0N  46.0W    55 KT
120HR VT     28/1800Z 27.0N  47.0W    55 KT


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