[Tropical] Tropical Cyclone Discussion

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WTNT41 KNHC 181435
TCDAT1
TROPICAL STORM JEANNE DISCUSSION NUMBER  20
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
11 AM EDT SAT SEP 18 2004

SATELLITE IMAGES INDICATE THAT THE CLOUD PATTERN ASSOCIATED WITH
JEANNE IS GRADUALLY RECOVERING FROM THE INTERACTION WITH
HISPANIOLA. THE LOW-LEVEL CENTER IS LOCATED UNDER THE INCREASING
CONVECTION AND T-NUMBERS ARE UP TO 3.0 ON THE DVORAK SCALE. LATEST
AIRCRAFT MEASURED A FLIGHT LEVEL WIND OF 54 KNOTS AND GRAND TURK
HAS REPORTED 41 KNOTS.  BASED ON THIS INFORMATION...THE INITIAL
INTENSITY HAS BEEN INCREASED TO 45 KNOTS. WATER VAPOR IMAGES SHOW
AN UPPER-LOW SWINGING SOUTHWARD AROUND THE WESTERN PORTION OF
JEANNE. THIS PATTERN WOULD RESULT IN THE RELAXATION OF THE SHEAR
FOLLOWED BY SOME STRENGTHENING. JEANNE HAS THE CHANCE TO REGAIN
HURRICANE STATUS IN THE NEXT DAY OR TWO BEFORE THE SHEAR INCREASES
AGAIN. THE OFFICIAL FORECAST GOES ALONG WITH BOTH SHIPS AND THE
GFDL.

JEANNE IS MOVING VERY SLOWLY TOWARD THE NORTH-NORTHWEST OR 340
DEGREES AT 6 KNOTS AROUND THE PERIPHERY OF A WEAK SUBTROPICAL
RIDGE. A SHARP MID-TO UPPER LEVEL TROUGH...PARTIALLY RELATED TO
IVAN...IS EXPECTED TO BE MOVING EASTWARD CREATING A WEAKNESS TO THE
NORTH OF THE CYCLONE. THIS PATTERN WOULD FORCE JEAN TO MOVE ON A
GENERAL NORTHWARD TRACK DURING THE NEXT 3 DAYS. THEREAFTER...A
RATHER STRONG HIGH IS EXPECTED TO REPLACE THE TROUGH AND DEPENDING
HOW FAR NORTH JEANNE MOVES...THE CYCLONE COULD BE BLOCKED AND MOVE
WESTWARD OR COULD TURN NORTHEASTWARD FOLLOWING THE TROUGH. SINCE
THERE IS MUCH UNCERTAINTY IN GLOBAL MODELS BEYOND 3 DAYS...THE BEST
OPTION AT THIS TIME IS TO KEEP JEAN NEARLY STATIONARY BETWEEN
BERMUDA AND THE BAHAMAS AT DAYS 4 AND 5. IN FACT...THE GFS KEEP THE
CYCLONE LOOPING WITHIN THIS REGION THROUGH THE PERIOD.

FORECASTER AVILA

FORECAST POSITIONS AND MAX WINDS

INITIAL      18/1500Z 21.4N  73.0W    45 KT
 12HR VT     19/0000Z 22.2N  73.2W    55 KT
 24HR VT     19/1200Z 23.5N  73.5W    60 KT
 36HR VT     20/0000Z 25.0N  73.5W    65 KT
 48HR VT     20/1200Z 26.5N  73.5W    70 KT
 72HR VT     21/1200Z 28.0N  73.5W    65 KT
 96HR VT     22/1200Z 29.0N  73.0W    65 KT
120HR VT     23/1200Z 29.1N  73.0W    65 KT


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