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HURRICANE ISIDORE DISCUSSION NUMBER  26
NATIONAL WEATHER SERVICE MIAMI FL
11 AM EDT SUN SEP 22 2002
 
AIR FORCE RESERVE HURRICANE HUNTERS FOUND A MINIMUM PRESSURE OF 934 
MB A FEW HOURS AGO...WHICH WOULD GENERALLY CORRESPOND TO ABOUT 128 
KT.  ALL THREE SATELLITE AGENCIES ALSO REPORTED A DVORAK SATELLITE 
INTENSITY ESTIMATE OF T6.5...OR 127 KT. HOWEVER...THE HIGHEST 
FLIGHT-LEVEL WIND RECORDED THUS FAR HAS ONLY BEEN 122 KT WHICH 
CONVERTS TO A SURFACE WIND SPEED OF ABOUT 110 KT...EVEN THOUGH 
DROPSONDE WINDS HAVE BEEN AS HIGH AS 133 KT JUST A FEW HUNDRED FEET 
ABOVE THE SURFACE. WHILE ALL INDICATIONS ARE THAT ISIDORE IS 
PROBABLY A CATEGORY 4 HURRICANE...I AM CONSTRAINED TO HOLD THE 
INTENSITY AT 110 KT UNTIL HIGHER WIND SPEEDS ARE MEASURED BY 
SUBSEQUENT RECON FLIGHTS.

THE INITIAL MOTION ESTIMATE IS 255/07. THERE IS NO SIGNIFICANT 
CHANGE TO THE PREVIOUS FORECAST TRACK OR REASONING. ISIDORE HAS BEEN 
WOBBLING ABOUT A MEAN WEST OR WEST-SOUTHWESTWARD DIRECTION THE PAST 
12 HOURS...WHICH IS TYPICAL OF RAPIDLY DEEPENING TROPICAL CYCLONES. 
ALL OF THE NHC MODEL GUIDANCE AGREES ON A GENERAL WEST OR SLIGHTLY 
WEST-SOUTHWESTWARD MOTION THROUGH 36 HOURS AND THEN DIVERGE 
SIGNIFICANTLY AFTER THAT WITH SOME MODELS TAKING ISIDORE NORTHWARD 
WHILE OTHERS TAKE THE CYCLONE SOUTHWESTWARD. THE OFFICIAL TRACK IS 
JUST AN EXTENSION OF THE PREVIOUS FORECAST TRACK AND IS BETWEEN THE 
AVN AND THE AVN ENSEMBLE MEAN MODELS.
 
THERE IS NO SIGNIFICANT CHANGE TO THE PREVIOUS INTENSITY FORECAST. 
AS LONG AS ISIDORE DOES NOT MOVE INLAND OVER YUCATAN...SOME SLOW 
INTENSIFICATION IS STILL POSSIBLE DUE TO THE LOW SHEAR AND ABUNDANCE 
OF WARM GULF WATER. THE SHIPS INTENSITY MODEL BRINGS ISIDORE TO 127 
KT IN 48 HOURS AND 130 KT IN 60 HOURS. NOTE THAT WITH INTENSE 
TROPICAL CYCLONES...THERE IS NO WAY TO FORECAST EYEWALL REPLACEMENT 
CYCLES WITH ANY ACCURACY BEYOND ABOUT 12 HOURS...SO THERE MAY BE 
SOME INTENSITY FLUCTUATIONS THROUGHOUT THE FORECAST PERIOD.
 
FORECASTER STEWART
 
FORECAST POSITIONS AND MAX WINDS
 
INITIAL     22/1500Z 21.8N  88.5W   110 KTS
12HR VT     23/0000Z 21.6N  89.6W   115 KTS
24HR VT     23/1200Z 21.3N  90.5W   120 KTS
36HR VT     24/0000Z 21.3N  91.2W   120 KTS
48HR VT     24/1200Z 21.5N  92.0W   125 KTS
72HR VT     25/1200Z 22.5N  93.0W   125 KTS
 
 
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