[Tropical] Tropical Cyclone Discussion

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WTNT44 KNHC 140231
TCDAT4
HURRICANE IVAN DISCUSSION NUMBER  47
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
11 PM EDT MON SEP 13 2004

A SHORT TIME AGO...THE EASTERN EYEWALL OF THE HURRICANE PASSED OVER
THE WESTERN TIP OF CUBA.  THE LAST CENTRAL PRESSURE READINGS FROM
BOTH THE AIR FORCE AND NOAA HURRICANE HUNTERS WAS 914 MB A FEW
HOURS AGO...SUGGESTING THAT IVAN WAS MAINTAINING ITS INTENSITY...
AND IT DOES NOT APPEAR THAT ENOUGH OF THE CORE INTERACTED WITH LAND
TO CAUSE SIGNIFICANT WEAKENING.  THEREFORE...THE CURRENT INTENSITY
IS HELD AT 140 KT FOR THIS ADVISORY.  SOME WEAKENING IS FORECAST AS
IVAN MOVES FARTHER NORTH OVER THE EASTERN GULF OF MEXICO DURING THE
NEXT COUPLE OF DAYS...AND ENCOUNTERS SOME WESTERLY SHEAR...HOWEVER
IVAN SHOULD STILL BE A MAJOR HURRICANE WHEN IT REACHES THE UNITED
STATES COAST.

IVAN WOBBLED NORTH-NORTHWESTWARD A FEW HOURS AGO AND NOW THE
ESTIMATED MOTION IS JUST BETWEEN NORTHWEST AND NORTH-NORTHWEST...
325/8. THE PRIMARY STEERING MECHANISM FOR THE HURRICANE IS A
MID-TROPOSPHERIC RIDGE NEAR AND EAST OF THE FLORIDA PENINSULA. THE
CONSENSUS OF THE DYNAMICAL TRACK PREDICTION MODELS SHOWS A
NORTHWESTWARD TO NORTH-NORTHWESTWARD MOTION FOLLOWED BY A TURN TO
THE NORTH AS THE HURRICANE MOVES INTO THE NORTHERN GULF OF MEXICO.
AS THE CENTER NEARS THE COAST...A SLIGHT TURN TO THE EAST COULD
OCCUR AS THE SYSTEM BEGINS TO RESPOND TO SLIGHT WESTERLY STEERING
FLOW.  ONCE AGAIN...THE OFFICIAL FORECAST TRACK HAS BEEN SHIFTED A
LITTLE TO THE WEST...AND IS IN BEST AGREEMENT WITH THE LATEST GFDL
AND GFS SOLUTIONS. THE LATEST FSU SUPERENSEMBLE RUN IS ONLY
SLIGHTLY TO THE WEST OF THE NHC TRACK.

THE SIZE OF THE HURRICANE AND THE FORECAST TRACK REQUIRE THE
ISSUANCE OF A HURRICANE WATCH FOR A PORTION OF THE NORTHERN GULF
COAST AT THIS TIME.  ONCE AGAIN WE EMPHASIZE THAT...DUE TO FORECAST
ERRORS...ONE SHOULD NOT FOCUS ON THE EXACT FORECAST TRACK AS THE
EVENTUAL LANDFALL POINT.  THE ENTIRE HURRICANE WATCH AREA IS AT
RISK.

FORECASTER PASCH

FORECAST POSITIONS AND MAX WINDS

INITIAL      14/0300Z 22.0N  85.4W   140 KT
 12HR VT     14/1200Z 23.1N  86.2W   140 KT
 24HR VT     15/0000Z 24.8N  87.3W   135 KT
 36HR VT     15/1200Z 26.6N  88.2W   130 KT
 48HR VT     16/0000Z 28.5N  88.5W   120 KT
 72HR VT     17/0000Z 32.0N  87.5W    65 KT...INLAND
 96HR VT     18/0000Z 34.0N  86.0W    20 KT...INLAND
120HR VT     19/0000Z 35.5N  83.5W    20 KT...INLAND

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