[Tropical] Tropical Cyclone Discussion

[Nashville EMWIN]

WTNT44 KNHC 102033
TCDAT4
HURRICANE IVAN DISCUSSION NUMBER  34
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
5 PM EDT FRI SEP 10 2004

THERE HAS BEEN NO SIGNIFICANT CHANGES IN THE INTENSITY OR TRACK OF
IVAN TODAY. THE HURRICANE HAS A DISTINCT EYE WITHIN A LARGE CENTRAL
DENSE OVERCAST AND PLENTY OF BANDING FEATURES. THE OUTFLOW REMAINS
WELL ESTABLISHED PRIMARILY TO THE WEST. THE PRESSURE HAS BEEN
OSCILLATING DURING THE DAY AND THE LAST READING FROM A
RECONNAISSANCE PLANE WAS 937 MB. INITIAL INTENSITY IS ADJUSTED TO
120 KNOTS BASED ON WIND DATA FROM THE RECONNAISSANCE PLANE. SOME
FLUCTUATIONS IN INTENSITY ARE LIKELY BEFORE IVAN MOVES NEAR OR OVER
JAMAICA WHERE THE EFFECTS OF THE HIGH TERRAIN MAY WEAKEN THE
HURRICANE. IT IS POSSIBLE THAT IVAN WILL RE-STRENGTHEN SOME BETWEEN
THE CAYMAN ISLANDS AND CUBA WHERE THERE IS A VERY HIGH OCEANIC HEAT
CONTENT AND THE SHEAR IS EXPECTED TO REMAIN WEAK.  ONCE IN THE GULF
OF MEXICO...THE SHEAR IS FORECAST TO INCREASE AND IVAN SHOULD
GRADUALLY WEAKEN. HOWEVER...IVAN IS EXPECTED TO REMAIN A DANGEROUS
HURRICANE UNTIL IT REACHES THE UNITED STATES.

THE HURRICANE IS MOVING TOWARD THE WEST-NORTHWEST OR 300 DEGREES AT
11 KNOTS STEERED BY A PERSISTENT SUBTROPICAL RIDGE OVER THE
BAHAMAS. AS THE RIDGE WEAKENS...AND A TROUGH DEVELOPS IN THE GULF OF
MEXICO...THE HURRICANE WILL LIKELY TURN MORE TO THE NORTHWEST WITH
A DECREASE IN FORWARD SPEED. THE FORECAST REMAINS UNCERTAIN AFTER
THE HURRICANE CROSSES CUBA. HOWEVER...MODELS ARE BECOMING IN BETTER
AGREEMENT ON A TRACK ACROSS THE EASTERN GULF OF MEXICO. ALTHOUGH
THE OFFICIAL FORECAST COULD HAVE BEEN SHIFTED A LITTLE WESTWARD DUE
TO THE NEW GUIDANCE...IT IS NOT PRUDENT TO MAKE A CHANGE AT THIS
TIME.  THE OFFICIAL FORECAST IS NOW BASICALLY TO THE RIGHT OF THE
GUIDANCE ENVELOPE...AND KEEPS THE HURRICANE ON A NORTHWARD TRACK
VERY CLOSE TO THE FLORIDA WEST COAST.

FORECASTER AVILA

FORECAST POSITIONS AND MAX WINDS

INITIAL      10/2100Z 17.0N  76.2W   120 KT
 12HR VT     11/0600Z 17.7N  77.5W   115 KT NEAR JAMAICA
 24HR VT     11/1800Z 18.8N  78.7W   120 KT
 36HR VT     12/0600Z 19.9N  79.8W   125 KT
 48HR VT     12/1800Z 21.3N  81.1W   130 KT NEARING CUBA
 72HR VT     13/1800Z 24.7N  82.7W   110 KT
 96HR VT     14/1800Z 29.0N  83.5W   100 KT
120HR VT     15/1800Z 34.0N  83.5W    30 KT...INLAND


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