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HURRICANE ISAAC DISCUSSION NUMBER  23
NATIONAL WEATHER SERVICE MIAMI FL
11 PM EDT TUE SEP 26 2000
 
ISAAC HAS REDEVELOPED DEEP CONVECTION OVER THE LOW-LEVEL CENTER AND
A WEAK EYE FEATURE CAN BE SEEN IN INFRARED IMAGERY.  THE INITIAL
INTENSITY IS MAINTAINED AT 80 KT BASED ON A SATELLITE INTENSITY
ESTIMATE OF 80 KT FROM BOTH TAFB AND SAB.  THE INITIAL POSITION WAS
LOCATED JUST A LITTLE TO THE SOUTHWEST OF THE SATELLITE FIX
POSITIONS DUE TO SOME SOUTHWESTERLY SHEAR DISPLACING THE MID- AND
UPPER-LEVEL CIRCULATIONS TO THE NORTHEAST OF THE LOW-LEVEL CENTER.
 
INITIAL MOTION ESTIMATE IS 300/11.  THERE IS NO SIGNIFICANT CHANGE
TO THE PREVIOUS FORECAST TRACK OR REASONING.  ISAAC MADE A LARGE
WOBBLE TOWARD THE NORTHWEST...OR 320 DEGREES...DURING THE PAST 6
HOURS AS THE CONVECTION REDEVELOPED AROUND THE CENTER.  HOWEVER...A
GENERAL TRACK TOWARD THE WEST-NORTHWEST SHOULD RESUME NOW THAT ISAAC
IS BEING STEERED BY THE DEEP LAYER FLOW AGAIN.  THE OFFICIAL TRACK
IS JUST EAST OF THE PREVIOUS FORECAST THROUGH 36 HOURS DUE TO THE
RECENT RIGHTWARD SHIFT IN THE POSITION...BUT AFTERWARDS THE OFFICIAL
TRACK IS CLOSE TO THE PREVIOUS FORECAST.  THIS IS CONSISTENT WITH
ALL OF THE MODEL GUIDANCE...WHICH IS TIGHTLY PACKED AROUND THE
PREVIOUS FORECAST TRACK.

THERE IS NO CHANGE TO THE PREVIOUS INTENSITY FORECAST OR REASONING. 
HOWEVER...THE 12 FT SEAS RADII WERE INCREASED SIGNIFICANTLY BASED ON
RECENT SHIP REPORTS WELL TO THE NORTHWEST AND NORTHEAST OF ISAAC.
 
FORECASTER STEWART
 
FORECAST POSITIONS AND MAX WINDS
 
INITIAL     27/0300Z 20.1N  46.2W    80 KTS
12HR VT     27/1200Z 21.0N  47.7W    80 KTS
24HR VT     28/0000Z 22.3N  49.6W    80 KTS
36HR VT     28/1200Z 23.7N  51.5W    85 KTS
48HR VT     29/0000Z 25.5N  53.5W    90 KTS
72HR VT     30/0000Z 30.5N  57.0W    90 KTS
 
 
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