[Tropical] Tropical Cyclone Discussion

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WTNT41 KNHC 221425
TCDAT1
HURRICANE JEANNE DISCUSSION NUMBER  36
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
11 AM EDT WED SEP 22 2004

SINCE THE EARLIER HURRICANE HUNTER FLIGHT THIS MORNING...THE
CONVECTIVE PATTERN HAS IMPROVED AS INDICATED BY A CONSENSUS DVORAK
INTENSITY ESTIMATE OF T5.0...OR 90 KT. HOWEVER...THE EYE HAS BECOME
CLOUD COVERED AGAIN AND 3-HR AVERAGE AODT VALUES ARE T4.6...OR 80
KT FROM CIMSS...AND T4.8...OR 85 KT...FROM TAFB. BASED ON THE
IMPROVED INNER-CORE CONVECTIVE PATTERN...THE INITIAL INTENSITY OF
JEANNE HAS BEEN INCREASED TO 85 KT...WHICH IS CONSISTENT WITH THE
LAST RECON CENTRAL PRESSURE REPORT OF 968 MB.

THE INITIAL MOTION IS 180/4.  THERE REMAINS NO SIGNIFICANT CHANGE TO
THE PREVIOUS TRACK FORECAST AND REASONING. JEANNE HAS MADE A TURN
TO THE SOUTH OVER THE PAST 6 HOURS...AND A GRADUAL TURN TOWARD THE
SOUTHWEST IS EXPECTED WITHIN THE NEXT 12 HOURS...FOLLOWED BY A SLOW
WESTWARD MOTION. A DEEP-LAYER HIGH CENTERED OVER OHIO WITH A RIDGE
EXTENDING SOUTHEASTWARD TO NEAR BERMUDA HAS BEEN GRADUALLY MOVING
EASTWARD. OVER THE NEXT 5 DAYS...THE CENTER OF THE RIDGE IS
FORECAST TO GRADUALLY MOVE TO A POSITION NEAR BERMUDA. THE
CLOCKWISE FLOW AROUND THE HIGH/RIDGE IS EXPECTED TO SLOWLY INCREASE
AND MOVE JEANNE NORTHWESTWARD BY 72 HOURS AND THEN MORE NORTHWARD
BY 96 HOURS. THE NHC MODEL GUIDANCE REMAINS IN GOOD AGREEMENT ON
THIS SCENARIO...WITH ONLY THE NOGAPS MODEL BEING THE WESTERNMOST
OUTLIER IN TAKING JEANNE ACROSS CENTRAL FLORIDA. THE NOGAPS
SCENARIO IS NOT BEING CONSIDERED AT THIS TIME DUE TO ITS MUCH
SLOWER EASTWARD MOVEMENT OF THE RIDGE TO THE NORTH OF JEANNE.

THE VERTICAL SHEAR IS FORECAST TO WEAKEN TO LESS THAN 5 KT IN 24
HOURS...SO SOME SLIGHT STRENGTHENING COULD OCCUR AT THAT TIME.
HOWEVER...THE MOST FAVORABLE UPPER-LEVEL PATTERN IS NOT EXPECTED TO
DEVELOP ACROSS JEANNE UNTIL AROUND 72 HOURS WHEN JEANNE IS FORECAST
TO MOVE UNDERNEATH THE WESTERN PORTION OF A SYNOPTIC-SCALE
ANTICYCLONE WITH A SHARP DIGGING TROUGH TO THE EAST. THAT PATTERN
WOULD ACT TO ENHANCE THE OUTFLOW IN THE EASTERN SEMICIRCLE...BUT
VERY DRY AIR IS EXPECTED TO SURROUND JEANNE AT THAT TIME. THE
INTENSITY FORECAST IS CLOSE TO THE CONSERVATIVE SHIPS INTENSITY
MODEL...BUT IF NO DRY AIR GETS WRAPPED INTO THE INNER-CORE REGION
THEN JEANNE COULD EASILY BE 5-10 KT STRONGER THAN FORECAST.

FORECASTER STEWART

FORECAST POSITIONS AND MAX WINDS

INITIAL      22/1500Z 26.3N  68.5W    85 KT
 12HR VT     23/0000Z 26.0N  68.9W    85 KT
 24HR VT     23/1200Z 26.0N  69.8W    90 KT
 36HR VT     24/0000Z 26.0N  70.9W    90 KT
 48HR VT     24/1200Z 26.3N  72.3W    90 KT
 72HR VT     25/1200Z 27.5N  75.2W    90 KT
 96HR VT     26/1200Z 29.5N  77.0W    80 KT
120HR VT     27/1200Z 33.0N  77.5W    70 KT


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