[Tropical] Tropical Cyclone Discussion

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WTNT41 KNHC 170248
TCDAT1
TROPICAL STORM JEANNE DISCUSSION NUMBER  14
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
11 PM EDT THU SEP 16 2004

THE CENTER HAS BEEN MAINLY OVER LAND SINCE EARLIER TODAY...HOWEVER
RECENTLY A PORTION OF THE CORE HAS MOVED OVER A VERY SMALL AREA OF
WATER...THE BAHIA DE SAMANA ON THE NORTH COAST OF THE DOMINICAN
REPUBLIC. ON INFRARED SATELLITE IMAGES...THERE HAS BEEN AN INCREASE
IN THE STRENGTH OF THE RING OF CONVECTION SURROUNDING THE EYE OVER
THE PAST FEW HOURS. THE SYSTEM IS BEING KEPT JUST BELOW HURRICANE
STRENGTH ON THIS ADVISORY SINCE MUCH OF THE CIRCULATION IS STILL
OVER LAND. IF THE CENTER MOVES FAR ENOUGH AWAY FROM THE COAST BY
EARLY FRIDAY...AN AIR FORCE RESERVE UNIT HURRICANE HUNTER AIRCRAFT
WILL BE ABLE TO GET TO THE CENTER AND PROVIDE A GOOD ESTIMATE OF
THE ACTUAL STRENGTH OF THE TROPICAL CYCLONE. OVER THE NEXT SEVERAL
DAYS...THE UPPER-LEVEL WINDS APPEAR TO BE FAVORABLE FOR
INTENSIFICATION. HOWEVER LATE IN THE PERIOD THE GFS 200 MB WIND
FORECAST SUGGESTS INCREASING SOUTHWESTERLY SHEAR OVER
JEANNE...ASSUMING THAT IT MORE OR LESS FOLLOWS OUR FORECAST TRACK.
THIS WOULD TEND TO INHIBIT STRENGTHENING AT DAYS 4 AND 5. IF THE
TROPICAL CYCLONE MOVES TO THE SOUTH OF OUR TRACK...IT COULD
INTENSIFY FURTHER SINCE IT WOULD LIKELY BE SOUTH OF THE STRONGER
SHEAR.

THE MOTION HAS BEEN ERRATIC SINCE THIS AFTERNOON...WITH A
NORTHWESTWARD WOBBLE NOTED SEVERAL HOURS AGO THAT BROUGHT THE
CENTER TO THE NORTH COAST OF HISPANIOLA. NOW THE MOTION APPEARS TO
BE WEST-NORTHWESTWARD...ABOUT 295/5. A WEAK RIDGE TO THE NORTH OF
THE STORM WILL BE THE MAIN STEERING FACTOR FOR THE NEXT DAY OR SO.
THEREAFTER...THE STEERING ENVIRONMENT BECOMES LESS CERTAIN.  AFTER
JEANNE MOVES INTO THE BAHAMAS...THE LARGE CIRCULATION OF IVAN IS
EXPECTED TO WEAKEN THE RIDGE...AND INDUCE A MORE NORTHWARD TRACK.
THE GLOBAL MODELS BUILD A STRONG MID-TROPOSPHERIC HIGH NEAR THE
NORTHEASTERN UNITED STATES BY 5 DAYS.  THIS MAKES IT UNLIKELY THAT
JEANNE WILL BE ABLE TO VEER OUT TO SEA...AND IN FACT IT MAY BE
FORCED TO TURN MORE WESTWARD BY THAT TIME.  IT IS MUCH TOO EARLY TO
TALK ABOUT WHAT PORTION OF THE SOUTHEAST U.S. COAST MAY BE
THREATENED.

FORECASTER PASCH

FORECAST POSITIONS AND MAX WINDS

INITIAL      17/0300Z 19.4N  69.7W    60 KT
 12HR VT     17/1200Z 20.0N  70.8W    60 KT
 24HR VT     18/0000Z 21.1N  72.4W    65 KT
 36HR VT     18/1200Z 22.3N  73.7W    70 KT
 48HR VT     19/0000Z 23.6N  74.9W    75 KT
 72HR VT     20/0000Z 26.5N  76.9W    80 KT
 96HR VT     21/0000Z 29.5N  79.0W    85 KT
120HR VT     22/0000Z 32.0N  81.0W    85 KT


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