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HURRICANE ISIDORE DISCUSSION NUMBER  16
NATIONAL WEATHER SERVICE MIAMI FL
11 PM EDT THU SEP 19 2002
 
THE LAST FIX FROM AN AIR FORCE PLANE NEAR 2300 UTC REPORTED A 
MINIMUM PRESSURE OF 981 MB.  ON ITS WAY HOME...A DROPSONDE LAUNCHED 
FROM THE PLANE REPORTED WINDS ABOVE THE SURFACE RANGING FROM 90 TO 
95 KNOTS. SINCE THEN... SATELLITE IMAGES HAVE INDICATED THAT ISIDORE 
HAS BECOME STRONGER AS INDICATED BY DVORAK T-NUMBERS WHICH HAVE 
INCREASED TO 4.5 AND 5.0.  INITIAL INTENSITY IS ADJUSTED TO 75 KNOTS 
AT THIS TIME WITH AN ESTIMATED PRESSURE OF 979 MB. THE NEXT PLANE 
WILL BE IN THE AREA AT 0600 UTC.

ALL PARAMETERS APPEAR TO BE FAVORABLE FOR STRENGTHENING. ISIDORE IS 
BECOMING A LARGE CYCLONE WITH AN EXPANSIVE OUTFLOW...FEEDER BANDS 
AND IS MOVING OVER THE HIGHER UPPER-OCEANIC HEAT CONTENT OF THE 
BASIN. IN ADDITION...SHIPS MODEL INDICATES THAT 4 OF 5 REQUIRED 
PARAMETERS FOR RAPID INTENSIFICATION ARE MET. THEREFORE...ISIDORE IS 
FORECAST TO BECOME A MAJOR HURRICANE IN THE EXTREME SOUTHEAST GULF 
OF MEXICO.

A HINT OF THE EYE CAN BE OBSERVED FROM BOTH HAVANA AND KEY WEST 
RADARS. THESE OBSERVATIONS COMBINED WITH SATELLITE FIXES GIVE AN 
INITIAL MOTION OF 305 DEGREES AT 7 KNOTS...WHICH IS BASICALLY THE 
SAME AS 6 HOURS AGO. NO CHANGE IN TRACK IS EXPECTED FOR THE NEXT 48 
HOURS AND ISIDORE WILL BE SPENDING FRIDAY CROSSING THE WESTERNMOST 
PORTION OF CUBA. THEREAFTER...THE FORECAST TRACK BECOMES HIGHLY 
UNCERTAIN. GLOBAL MODELS SLOW THE SYSTEM DOWN TO A HALT IN THE 
SOUTHEASTERN GULF OF MEXICO AS STEERING CURRENTS COLLAPSE DUE TO THE 
PASSAGE OF A MID-LEVEL TROUGH TO THE NORTH. AT LONGER RANGE...ALL 
MODELS MOVE THE HURRICANE ON A GENERAL NORTHWARD TRACK EXCEPT THE 
NCEP GLOBAL MODEL. THE LATTER MOVES THE HURRICANE SOUTHWESTWARD 
TOWARD THE BAY OF CAMPECHE.  THIS SOLUTION IS PROBABLY DUE TO A 
STRONG LOW WHICH THE MODEL DEVELOPS JUST NORTH OF THE BAHAMAS. IT IS 
TEMPTING TO GO WITH THE NCEP MODEL SOLUTION SINCE THIS MODEL HAS 
BEEN VERY RELIABLE. BUT FOR NOW...IT IS BETTER TO KEEP THE HURRICANE 
WITH A NORTHWESTWARD DRIFT BEYOND 48 HOURS UNTIL THE STEERING 
PATTERN BECOMES MORE CLEAR. 
 
FORECASTER AVILA
 
FORECAST POSITIONS AND MAX WINDS
 
INITIAL     20/0300Z 21.0N  82.5W    75 KTS
12HR VT     20/1200Z 21.7N  83.5W    85 KTS
24HR VT     21/0000Z 22.5N  84.5W    95 KTS
36HR VT     21/1200Z 23.0N  85.5W   100 KTS
48HR VT     22/0000Z 23.5N  86.5W   105 KTS
72HR VT     23/0000Z 24.0N  87.0W   105 KTS
 
 
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