[Tropical] Tropical Cyclone Discussion

[EMWIN Server]

WTNT44 KNHC 160252
TCDAT4
HURRICANE IVAN DISCUSSION NUMBER  55
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
11 PM EDT WED SEP 15 2004

THE EYE REMAINS WELL-DEFINED ON SATELLITE IMAGES...BUT ON THE MOBILE
WSR-88D RADAR...THERE HAS BEEN AN EROSION OF THE SOUTHWEST
EYEWALL.  ALSO...THE NOAA PLANE REPORTED THAT THE EYEWALL WAS OPEN
TO THE SOUTHWEST.  GPS DROPSONDE DATA AT 200 MB FROM THIS EVENING'S
NOAA G-IV JET MISSION DO NOT SUGGEST MUCH VERTICAL SHEAR IN THE
ENVIRONMENT OF IVAN...ALTHOUGH THERE IS SOME WESTERLY FLOW INTO THE
HURRICANE AT 250 AND 300 MB.  NO LARGE CHANGES IN STRENGTH ARE
LIKELY UNTIL THE CENTER REACHES THE COAST...AND IVAN IS EXPECTED TO
MAKE LANDFALL AS A MAJOR HURRICANE.

OVER THE LAST FEW HOURS THE MOTION HAS BEEN SLIGHTLY EAST OF
NORTH...ABOUT 010/010.  BECAUSE OF THIS SLIGHT EASTWARD SHIFT IN
HEADING...THE TRACK HAS BEEN ADJUSTED SLIGHTLY TO THE RIGHT.  THIS
REMAINS CLOSE TO THE CONSENSUS OF THE TRACK MODELS AS WELL AS THE
LATEST FSU SUPERENSEMBLE RUN.

SINCE IVAN IS SO LARGE AND INTENSE...IT IS EXPECTED TO BRING
HURRICANE FORCE WINDS WELL INLAND...UP TO ABOUT 150 MILES ALONG ITS
TRACK.  NOTE THAT THE INLAND GUST FACTOR IS QUITE LARGE BECAUSE
HIGH MOMENTUM AIR...ALOFT...CAN BE BROUGHT TO THE SURFACE IN THE
CONVECTIVE CELLS.  LATER IN THE PERIOD...THE DYNAMICAL MODELS SHOW
THE FORWARD PROGRESS OF IVAN BEING BLOCKED.  THEREFORE THE OFFICIAL
FORECAST SHOWS IVAN STALLING NEAR THE SOUTHERN APPALACHIANS AND
SLOWLY DISSIPATING IN THAT AREA.  OBVIOUSLY THIS COULD BE A MAJOR
FLOOD EVENT OVER PORTIONS OF THE SOUTHEASTERN U.S. IN THE COMING
DAYS.

FORECASTER PASCH

FORECAST POSITIONS AND MAX WINDS

INITIAL      16/0300Z 29.3N  88.1W   115 KT
 12HR VT     16/1200Z 31.0N  87.9W   110 KT...INLAND
 24HR VT     17/0000Z 33.0N  87.2W    60 KT...INLAND
 36HR VT     17/1200Z 34.5N  86.5W    30 KT...INLAND
 48HR VT     18/0000Z 35.5N  85.5W    25 KT...INLAND
 72HR VT     19/0000Z 36.0N  84.0W    20 KT...INLAND
 96HR VT     20/0000Z 36.0N  84.0W    20 KT...DISSIPATING
120HR VT     21/0000Z...DISSIPATED

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