[Tropical] Tropical Cyclone Discussion

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WTNT43 KNHC 210322
TCDAT3
TROPICAL STORM LISA DISCUSSION NUMBER   7
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
11 PM EDT MON SEP 20 2004

T-NUMBERS FROM TAFB AND SAB BOTH GIVE 45 KTS.  THE PREVIOUS
INTENSITY OF 55 KTS IS REDUCED TO 50 KTS FOR THIS ADVISORY.
KARLS OUTFLOW IS BEGINNING TO SHEAR THE SYSTEM AND THIS SHOULD MAKE
ANY STRENGTHENING RATHER DIFFICULT.  THE SHIPS MODEL ALSO SUGGESTS
THIS AND THE SYSTEM IS FORECAST TO UNDER GO LITTLE CHANGE DURING
THE NEXT TWO DAYS.  AFTER THAT TIME THE SHEAR BEGINS TO WEAKEN AND
THE SYSTEM IS FORECAST TO REACH HURRICANE STRENGTH.

THE INITIAL MOTION ESTIMATE IS 275/10...THE SAME AS IT WAS 24 HOURS
AGO. JEANNE IS MOVING WESTWARD WITHOUT ANY INFLUENCE FROM KARLS
CIRCULATION. THERE REMAINS NO SIGNIFICANT CHANGE TO THE PREVIOUS
TRACK FORECAST OR REASONING. LISA IS EXPECTED TO CONTINUE MOVING IN
A WEST TO WEST-NORTHWESTWARD DIRECTION THROUGHOUT THE FORECAST
PERIOD AS THE SMALL CYCLONE MOVES AROUND THE PERIPHERY OF A NARROW
SUBTROPICAL RIDGE LOCATED BETWEEN LISA AND KARL. THE ONLY MODEL
THAT HAS A HINT OF WHAT IS GOING ON IS THE GFDL...WHICH MOVES THE
SYSTEM WESTWARD AND EVEN SLIGHTLY SOUTH-WESTWARD BEGINNING AT THE 4
DAY FORECAST PERIOD.  THE OFFICIAL FORECAST IS ADJUSTED SLIGHTLY TO
THE LEFT TO COME MORE IN LINE WITH THE GFDL.

FORECASTER JARVINEN

FORECAST POSITIONS AND MAX WINDS

INITIAL      21/0300Z 13.8N  37.9W    50 KT
 12HR VT     21/1200Z 13.9N  39.4W    50 KT
 24HR VT     22/0000Z 14.5N  41.5W    50 KT
 36HR VT     22/1200Z 15.1N  43.0W    55 KT
 48HR VT     23/0000Z 15.4N  44.3W    55 KT
 72HR VT     24/0000Z 15.6N  46.2W    60 KT
 96HR VT     25/0000Z 15.7N  48.1W    70 KT
120HR VT     26/0000Z 16.1N  50.0W    70 KT


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