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TROPICAL STORM LISA DISCUSSION NUMBER   1
NATIONAL WEATHER SERVICE MIAMI FL
5 PM EDT MON OCT 05 1998
 
THE STRONG TROPICAL WAVE THAT WE HAVE BEEN FOLLOWING FOR SEVERAL
DAYS DISPLAYED A FAIRLY WELL DEFINED LOW LEVEL CIRCULATION ON
VISIBLE IMAGERY TODAY.  THE WEST HALF OF THE LOW LEVEL CIRCULATION
IS EXPOSED BUT THERE IS DEEP CONVECTION ON THE EAST SIDE.  AN
OBSERVATION OF 45 KNOTS FROM A DRIFTING BOUY IN THE DEEP CONVECTION
AT ABOUT 11Z IS THE BASIS FOR CALLING THIS SYSTEM A TROPICAL STORM. 
LISA MAY HAVE BEEN A STORM FOR 18 HOURS OR MORE...BUT IT WAS NOT
UNTIL THE CENTER BECAME VISIBLE THIS MORNING THAT THIS WAS KNOWN TO
BE THE CASE.  THE SHEARING IMPLIED BY THE EXPOSED CENTER AND STRONG
WESTERLIES IS THE BASIS ASSUMING THAT WEAKENING HAS OCCURRED TODAY.

THE TRACK GUIDANCE ALL SHOWS THE SYSTEM BEING RECURVED BY A MAJOR
TROUGH IN THE WESTERLIES IN 72 HOURS AND THE OFFICIAL TRACK FORECAST
IS SIMILAR TO THE GFDL AND AVIATION AND LBAR MODELS.  A POSSIBILTY
IS THAT A STRONG BAROCLINIC SYSTEM WILL ABSORB THE TROPICAL CYCLONE
...RESULTING IN A STRONGER SYSTEM THAN FORECAST IN THIS ADVISORY.
THE FORECAST TRACK INDICATES NO THREAT TO LAND.

LAWRENCE

FORECAST POSITIONS AND MAX WINDS
 
INITIAL     05/2100Z 16.4N  49.3W    40 KTS
12HR VT     06/0600Z 17.7N  50.8W    35 KTS
24HR VT     06/1800Z 19.5N  52.0W    30 KTS
36HR VT     07/0600Z 21.5N  51.5W    30 KTS
48HR VT     07/1800Z 23.5N  48.5W    30 KTS
72HR VT     08/1800Z 26.0N  43.0W    30 KTS
 
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