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HURRICANE ISAAC DISCUSSION NUMBER  15
NATIONAL WEATHER SERVICE MIAMI FL
11 PM EDT SUN SEP 24 2000
 
THE EYE OF ISAAC HAS BEEN INTERMITTENT IN INFRARED SATELLITE IMAGERY
THE PAST 6 HOURS...BUT SHOWS UP NICELY AS A 5NM DIAMETER EYE IN
RECENT TRMM AND SSMI OVERPASSES.  HOWEVER...A 1944Z TRMM OVERPASS
SHOWED THE MID-LEVEL CENTER DISPLACED A LITTLE TO THE NORTHEAST OF
THE LOW-LEVEL EYE...SO THE INITIAL POSITION IS SLIGHTLY SOUTH OF THE
SATELLITE POSITION ESTIMATES OBTAINED FROM THE VARIOUS SATELLITE
AGENCIES. THE INITIAL INTENSITY IS HELD AT 100 KT BASED ON SATELLITE
INTENSITY ESTIMATES OF 90 KT FROM ALL THREE AGENCIES...THE VERY COLD
TOPS OF -80 TO -82C THAT HAVE DEVELOPED NEAR THE EYE...PLUS THE
SMALL EYE SEEN IN MICROWAVE IMAGERY.  DUE TO THE SMALL EYE DIAMETER
...JUST A SMALL AMOUNT OF CLOUD COVER WILL OBSCURE THE EYE FEATURE
IN INFRARED IMAGERY AND CAUSE THE INTENSITY ESTIMATES TO BE LOW.

THE INITIAL MOTION ESTIMATE IS 300/08.  THERE ARE NO SIGNIFICANT
CHANGES TO THE PREVIOUS TRACK OR INTENSITY FORECASTS. ISAAC HAS MADE
A LARGE WOBBLE TO THE NORTHWEST DURING THE PAST 6 HOURS...BUT A
GENERAL TRACK BACK TOWARD 290 DEGREES IS EXPECTED ONCE THE INNER
CORE CONVECTIVE FLUCTUATIONS SMOOTH OUT.  ALL THE MODELS MAINTAIN
THE STRONG SUBTROPICAL RIDGE TO THE NORTH OF ISAAC THROUGHOUT THE
PERIOD...WHICH SHOULD KEEP ISAAC ON A GENERAL WEST-NORTHWEST TRACK. 
THE UKMET MODEL IS THE FASTEST MODEL AND TURNS ISAAC DUE WEST AFTER
48 HOURS.  THE OFFICIAL TRACK IS SLOWER AND TO THE RIGHT OF THE
UKMET AND CLOSE THE GUNS AND GFDL MODELS.
 
FORECASTER STEWART
 
FORECAST POSITIONS AND MAX WINDS
 
INITIAL     25/0300Z 16.4N  38.9W   100 KTS
12HR VT     25/1200Z 17.0N  40.0W   100 KTS
24HR VT     26/0000Z 17.8N  41.9W   100 KTS
36HR VT     26/1200Z 18.6N  44.1W   100 KTS
48HR VT     27/0000Z 19.5N  46.5W    95 KTS
72HR VT     28/0000Z 20.5N  51.0W    90 KTS
 
 
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