[Tropical] Tropical Cyclone Discussion

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WTNT41 KNHC 141440
TCDAT1
TROPICAL STORM JEANNE DISCUSSION NUMBER   4
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
11 AM EDT TUE SEP 14 2004

SATELLITE AND RADAR DATA INDICATE THAT TROPICAL DEPRESSION ELEVEN
HAS ACQUIRED ENOUGH BANDING FEATURES TO BE UPGRADED TO TROPICAL
STORM JEANNE. THE INITIAL INTENSITY IS BASED ON DVORAK SATELLITE
INTENSITY ESTIMATES OF 45 KT FROM BOTH TAFB AND SAB...AND 35 KT...
FROM AFWA. RECON WILL REACH JEANNE AROUND 18Z.

THE INITIAL MOTION ESTIMATE IS A SOMEWHAT UNCERTAIN 290/10. THE
ADVISORY POSITION AS ADJUSTED SLIGHTLY SOUTH OF THE PREVIOUS
POSITION AND FORECAST TRACK BASED ON RADAR DATA FROM GUADELOUPE.
HOWEVER...THIS MORE SOUTHERLY INITIAL POSITION MAY JUST BE DUE TO
DISRUPTION OF THE SURROUNDING DEEP CONVECTION BY SOME OF THE LARGER
LEEWARD ISLANDS. A MOTION TO THE WEST-NORTHWEST IS EXPECTED TO
RESUME SHORTLY...BUT THE FORECAST TRACK HAS BEEN ADJUSTED A LITTLE
SOUTH OR TO THE LEFT OF THE PREVIOUS FORECAST OWING TO THE MORE
SOUTHERLY INITIAL POSITION. THE NHC TRACK MODEL GUIDANCE IS IN VERY
GOOD AGREEMENT ON A WEST-NORTHWESTWARD MOTION THROUGH 72 HR. AFTER
THAT...THE MODEL GUIDANCE DIVERGES SIGNIFICANTLY WITH THE GFS AND
GFDL MODELS TURNING JEANNE MORE NORTHWARD...WHILE THE NOGAPS...
UKMET...AND CANADIAN MODELS TRENDING MORE WESTWARD. A STRONG RIDGE
IS ALREADY IN PLACE ACROSS THE WESTERN ATLANTIC FROM BERMUDA TO
FLORIDA...WHICH SEPARATES T.S. JEANNE FROM HURRICANE IVAN. ONLY THE
GFS AND GFDL WEAKEN THE RIDGE TO THE NORTH OF JEANNE IN THE LATER
PERIODS. THE REMAINDER OF THE MODELS MAINTAIN THE RIDGE AND EVEN
BUILD IT SLIGHTLY WESTWARD. THE FORECAST WAS SHIFTED SLIGHTLY
WESTWARD AT 96- AND 120-HOURS SIMILAR TO THE NOGAPS AND CANADIAN
MODELS...AND IS CLOSE TO THE GUNS CONSENSUS MODEL.

JEANNE IS CURRENTLY UNDERNEATH A FAIRLY FAVORABLE UPPER-LEVEL FLOW
PATTERN TO THE EAST OF AN AMPLIFYING UPPER-LEVEL TROUGH. THE ONLY
IMMEDIATE HINDERING INFLUENCE TO THE INTENSIFICATION PROCESS IS DRY
AIR PUNCHING INTO THE SYSTEM FROM THE NORTHWEST. HOWEVER...
SURROUNDING UPPER-AIR DATA SUGGESTS THAT THIS SHOULD BE SHORT-LIVED
AND STEADY INTENSIFICATION SHOULD OCCUR UNTIL JEANNE PASSES OVER OR
NEAR PUERTO RICO. IN THE LONGER TERM...JEANNE IS FORECAST TO PASS
NEAR THE BASE OF THE UPPER-LEVEL TROUGH IN 48-96 HOURS...WHICH
RESULTS IN 20-25 KT OF NORTHERLY SHEAR DURING THAT TIME PERIOD. THE
INTENSITY IS LEVELED OFF UNTIL 120 HOURS...WHEN THE SHEAR IS
EXPECTED TO WEAKEN TO LESS THAN 10 KT FROM AN EASTERLY DIRECTION.

FORECASTER STEWART

FORECAST POSITIONS AND MAX WINDS

INITIAL      14/1500Z 16.6N  63.1W    35 KT
 12HR VT     15/0000Z 17.3N  64.6W    45 KT
 24HR VT     15/1200Z 18.3N  66.3W    55 KT...INLAND PUERTO RICO
 36HR VT     16/0000Z 19.2N  68.0W    55 KT
 48HR VT     16/1200Z 20.0N  69.5W    60 KT
 72HR VT     17/1200Z 21.2N  71.3W    60 KT
 96HR VT     18/1200Z 22.5N  73.0W    60 KT
120HR VT     19/1200Z 24.5N  75.0W    70 KT


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