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HURRICANE GERT DISCUSSION NUMBER  43
NATIONAL WEATHER SERVICE MIAMI FL
11 PM EDT TUE SEP 21 1999
 
THE INITIAL MOTION ESTIMATE IS 020/16.  THE MOTION SCENARIO IS
UNCHANGED WITH THE 18Z AVIATION MODEL SHOWING GERT BEING STEERED BY
THE FLOW TO THE EAST OF A LARGE MID-TROPOSPHERIC TROUGH OVER THE
EASTERN U.S.  THE OFFICIAL FORECAST TRACK IS SIMILAR TO THE PREVIOUS
ADVISORY EXCEPT A LITTLE SLOWER AFTER 48 HOURS.  THIS IS SIMILAR TO
THE GFDL FORECAST AND TO THE LEFT OF MOST OTHER MODELS.  THE HPC
GUIDANCE IS THE ONLY TRACK FORECAST LEFT OF THE OFFICIAL.
 
DVORAK SATELLITE INTENSITY ESTIMATES INDICATE SLOW WEAKENING
CONTINUES.  COLD SSTS SHOULD BE ENCOUNTERED IN 24 HOURS OR SO AND
THIS SHOULD HASTEN THE WEAKENING PROCESS.  ALSO THE AVIATION MODEL
LOSES THE LOW LEVEL CIRCULATION AFTER 36 HOURS AS IT IS ABSORBED
INTO THE LARGER TROUGH.  SO THE FORECAST IS FOR WEAKENING AND
EXTRATROPICAL TRANSFORMATION OVER THE NEXT 3 DAYS...IF THE LOW LEVEL
CIRCULATION SURVIVES THAT LONG.
 
LAWRENCE
 
FORECAST POSITIONS AND MAX WINDS
 
INITIAL     22/0300Z 35.2N  60.8W    80 KTS
12HR VT     22/1200Z 37.8N  59.6W    75 KTS
24HR VT     23/0000Z 42.0N  57.0W    70 KTS
36HR VT     23/1200Z 46.0N  54.0W    60 KTS
48HR VT     24/0000Z 49.2N  50.0W    50 KTS...EXTRATROPICAL
72HR VT     25/0000Z 57.0N  44.0W    35 KTS...EXTRATROPICAL
 
 
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