[Tropical] Tropical Cyclone Discussion

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WTNT41 KNHC 212046
TCDAT1
HURRICANE JEANNE DISCUSSION NUMBER  33
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
5 PM EDT TUE SEP 21 2004

VISIBLE AND INFRARED SATELLITE IMAGERY...ALONG WITH DVORAK INTENSITY
ESTIMATES...INDICATE JEANNE HAS CHANGED LITTLE DURING THE PAST 6
HOURS. THE RAGGED EYE HAS BEEN INTERMITTENTLY CLOUD-COVERED AND THE
SATELLITE INTENSITY ESTIMATE REMAINS T4.5...OR 77KT...FROM TAFB AND
SAB. AS SUCH...THE INTENSITY ALSO REMAINS AT 80 KT. AN AIR FORCE
RESERVE RECON FLIGHT WILL INVESTIGATE JEANNE AGAIN AT 22/06Z.

THE INITIAL MOTION IS NOW 140/05.  AGAIN...THERE REMAINS NO
SIGNIFICANT CHANGE TO THE PREVIOUS FORECAST TRACK OR REASONING.
THE NHC MODEL GUIDANCE IS IN BETTER AGREEMENT NOW...EXCEPT FOR THE
GFS...ON JEANNE MAKING A SLOW ANTICYCLONIC LOOP DURING THE NEXT
36-48 HOURS BEFORE MOVING NORTHWEST AND EVENTUALLY NORTHWARD. WHILE
THE GFS IS STILL THE EASTERNMOST OUTLIER MODEL...EVEN IT HAS
CONTINUED TO SHIFT ITS TRACK FARTHER WEST CLOSER TO THE REST OF THE
OTHER MODELS. THE DEEP-LAYERED HIGH PRESSURE SYSTEM OVER THE
EASTERN U.S. IS SLOWLY BUILDING SOUTH AND EASTWARD TO THE NORTH OF
JEANNE AS A LARGE TROUGH TO THE NORTHEAST OF THE CYCLONE CONTINUES
TO SHIFT EASTWARD. THE OFFICIAL TRACK IS SIMILAR TO THE PREVIOUS
TWO FORECASTS...AND IS CLOSE TO THE GUNS CONSENSUS MODEL.

THE VERTICAL SHEAR ACROSS JEANNE IS STILL FORECAST TO WEAKEN TO LESS
THAN 10 KT IN 36-48 HOURS...SO SOME SLIGHT STRENGTHENING IS
POSSIBLE AROUND THAT TIME. BY 72 HOURS...HOWEVER...SIGNIFICANT
VERTICAL SHEAR FROM THE SOUTH AND SOUTHWEST IS FORECAST TO SPREAD
ACROSS JEANNE AS THE HURRICANE MOVES UNDERNEATH THE WESTERN
PERIPHERY OF A STRONG 200 MB ANTICYCLONE. THEREFORE...GRADUAL
WEAKENING IS EXPECTED. HWOEVERE...IF JEANNE SHOULD MOVE A LITTLE
FASTER AND A FARTHER WEST LIKE THE NOGAPS MODEL IS FORECASTING...
THEN THE HURRICANE WOULD LIKELY WEAKEN EVEN MORE THAN FORECAST
SINCE IT WOULD BE UNDER STRONGER UPPER-LEVEL FLOW.

FORECASTER STEWART

FORECAST POSITIONS AND MAX WINDS

INITIAL      21/2100Z 27.3N  68.8W    80 KT
 12HR VT     22/0600Z 27.0N  68.7W    80 KT
 24HR VT     22/1800Z 26.5N  68.7W    80 KT
 36HR VT     23/0600Z 26.2N  69.0W    85 KT
 48HR VT     23/1800Z 26.4N  69.6W    85 KT
 72HR VT     24/1800Z 27.3N  71.3W    80 KT
 96HR VT     25/1800Z 29.0N  73.5W    70 KT
120HR VT     26/1800Z 32.0N  74.5W    60 KT


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