[Tropical] Tropical Cyclone Discussion

[Nashville EMWIN]

WTNT44 KNHC 051426
TCDAT4
HURRICANE IVAN DISCUSSION NUMBER  12
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
11 AM EDT SUN SEP 05 2004

IVAN IS STRENGTHENING RATHER RAPIDLY AT THIS TIME.  THE EYE IS
BECOMING BETTER DEFINED ON THE VISIBLE IMAGERY AND DVORAK INTENSITY
ESTIMATES SUPPORT AT LEAST 75 KT FOR THE CURRENT INTENSITY.  THIS
MAKES IVAN THE STRONGEST TROPICAL CYCLONE FOR SUCH A LOW LATITUDE
IN THE ATLANTIC BASIN RECORDS.  CIRRUS OUTFLOW IS WELL ESTABLISHED
OVER ALL QUADRANTS OF THE HURRICANE.  ALL PARAMETERS SEEM TO BE IN
PLACE FOR IVAN TO CONTINUE STRENGTHENING...AND THERE IS A HIGH
LIKELIHOOD THAT THIS WILL BECOME THE SEASON'S FOURTH MAJOR
HURRICANE.  THE OFFICIAL WIND SPEED FORECAST IS SIMILAR TO THE
SHIPS GUIDANCE...AND IT MAY BE CONSERVATIVE.

THE MOTION CONTINUES AT ABOUT 280/18...AND THE SHORT-TERM MOTION MAY
BE EVEN FASTER.  THE TRACK FORECAST REASONING REMAINS ESSENTIALLY
UNCHANGED.  IVAN IS ON THE SOUTH SIDE OF A STRONG SUBTROPICAL
RIDGE...A REGIME THAT IS LIKELY TO CONTINUE FOR THE NEXT 3-4 DAYS
AND WHICH WOULD STEER THE HURRICANE WEST-NORTHWESTWARD OVER THAT
TIME SPAN.  IN THE 4-5 DAY TIME FRAME...THERE IS OF COURSE MORE
UNCERTAINTY...AND WHERE IVAN WINDS UP BY THE END OF THE PERIOD WILL
DEPEND LARGELY ON THE STRENGTH OF THE RIDGE TO ITS NORTH BY THAT
TIME.  THE OFFICIAL FORECAST IS IN GOOD AGREEMENT WITH THE
DYNAMICAL MODEL CONSENSUS...AND IN EVEN BETTER AGREEMENT WITH A
CONSENSUS THAT EXCLUDES THE GFS...I.E. GUNS.  THE GFS HAS NOT BEEN
SHOWING A REALISTIC SOLUTION SINCE IT WEAKENS IVAN INTO A TROPICAL
WAVE OVER THE CARIBBEAN.  GIVEN THE CURRENT TREND IN IVAN'S
INTENSITY...SUCH A SCENARIO DOES NOT SEEM VERY LIKELY AT THIS TIME.

THE WIND RADII HAVE BEEN ADJUSTED A LITTLE BASED ON A RECENT
QUIKSCAT PASS THAT COVERED THE CIRCULATION OF IVAN.

FORECASTER PASCH

FORECAST POSITIONS AND MAX WINDS

INITIAL      05/1500Z  9.9N  46.0W    75 KT
 12HR VT     06/0000Z 10.6N  48.7W    80 KT
 24HR VT     06/1200Z 11.5N  52.3W    85 KT
 36HR VT     07/0000Z 12.4N  55.9W    90 KT
 48HR VT     07/1200Z 13.3N  59.4W    95 KT
 72HR VT     08/1200Z 15.0N  65.5W   105 KT
 96HR VT     09/1200Z 17.5N  71.0W   110 KT
120HR VT     10/1200Z 20.5N  75.0W    70 KT...INLAND


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