[Tropical] Tropical Cyclone Discussion

[Nashville EMWIN]

WTNT44 KNHC 100813
TCDAT4
HURRICANE IVAN DISCUSSION NUMBER  32
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
5 AM EDT FRI SEP 10 2004

REPORTS FROM AN USAF RESERVE UNIT AIRCRAFT INDICATE THAT THE CENTRAL
PRESSURE IS UP SEVERAL MB FROM THE PREVIOUS MISSION...AND IS NOW
929 MB.  THE OBSERVED FLIGHT LEVEL AND DROPSONDE WINDS SUPPORT
ABOUT 125 KT OR LESS MAXIMUM SURFACE WIND ...SO THE OFFICIAL WIND
SPEED IS LOWERED TO THIS VALUE.  THE DEEP CONVECTIVE PATTERN LOOKS
A LITTLE RAGGED ON THE NORTH SIDE...BUT THE HURRICANE IS LIKELY
GOING THROUGH FLUCTUATIONS.  VERTICAL SHEAR AND SSTS ARE FAVORABLE
FOR FURTHER INTENSIFICATION FOR ABOUT 48 HOURS.  AFTER 48 HOURS...
THE LAND MASS OF CUBA AND INCREASING VERTICAL SHEAR SHOULD BRING
ABOUT SOME WEAKENING...BUT IVAN COULD STILL REMAIN A RATHER
POWERFUL HURRICANE AS IT MOVES OVER CUBA AND INTO THE GULF OF
MEXICO.

THE INITIAL MOTION ESTIMATE IS 300/11.  THE GLOBAL TRACK MODELS
REMAIN IN GOOD AGREEMENT ABOUT A TURN TOWARD THE NORTHWEST AND THEN
NORTH OVER THE NEXT 120 HOURS AS IVAN IS STEERED AROUND THE WESTERN
PERIPHERY OF THE SUBTROPICAL RIDGE WHICH HAS A WEAKNESS OVER THE
GULF OF MEXICO.  THERE IS SOME SPREAD TO THE MODELS AFTER 48 HOURS.
THE GFS...UKMET...AND GFDL ALL SHOW A TRACK OVER JAMAICA...THEN
WESTERN CUBA AND THEN FLORIDA.  THE NOGAPS AND FSU SUPERENSEMBLE
ARE FURTHER WEST AND ALSO SHOW A TRACK NEAR JAMAICA AND THEN OVER
WESTERN CUBA...BUT THEN MOVE IVAN OVER THE GULF TO THE WEST OF
FLORIDA.  THE OFFICIAL TRACK FORECAST IS SIMILAR TO AND AN UPDATE
OF THE PREVIOUS OFFICIAL ADVISORY AND SHOWS A TRACK OVER FLORIDA
IN GOOD AGREEMENT WITH A CONSENSUS OF THE MODELS.  IT REMAINS... OF
COURSE...MUCH TOO EARLY TO BE VERY CERTAIN ABOUT THE THREAT TO
FLORIDA.

THE GOVERNMENT OF CUBA HAS DECIDED TO WAIT A LITTLE LONGER BEFORE
PUTTING UP A HURRICANE OR TROPICAL STORM WARNING FOR SOUTHEASTERN
CUBA.

FORECASTER LAWRENCE

FORECAST POSITIONS AND MAX WINDS

INITIAL      10/0900Z 15.9N  74.2W   125 KT
 12HR VT     10/1800Z 16.9N  75.6W   125 KT
 24HR VT     11/0600Z 18.0N  77.4W   130 KT
 36HR VT     11/1800Z 19.1N  78.9W   135 KT
 48HR VT     12/0600Z 20.4N  80.2W   135 KT
 72HR VT     13/0600Z 23.3N  81.9W   115 KT
 96HR VT     14/0600Z 27.0N  82.5W   115 KT
120HR VT     15/0600Z 31.0N  82.5W    50 KT...INLAND


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