[Tropical] Tropical Cyclone Discussion

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WTNT41 KNHC 232054
TCDAT1
HURRICANE JEANNE DISCUSSION NUMBER  41
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
5 PM EDT THU SEP 23 2004

WHILE THE EYE OF JEANNE HAS BECOME A LITTLE MORE DISTINCT...
SATELLITE IMAGERY ALSO INDICATES THAT THE OVERALL CONVECTIVE
STRUCTURE HAS CHANGED LITTLE THIS AFTERNOON...SO THE INTENSITY IS
BEING MAINTAINED AT 90 KT. THE NEXT RECON FLIGHT INTO JEANNE WILL
BE AROUND 24/06Z

THE INITIAL MOTION IS 290/06. JEANNE HAS BEEN WOBBLING IN A GENERAL
WEST-NORTHWESTWARD MOTION THE PAST 9 HOURS...BUT A TURN TOWARD TO
THE WEST IS EXPECTED TO BEGIN LATER TONIGHT OR EARLY FRIDAY. THIS
HAS BEEN THE YEAR FOR WRAPAROUND RIDGES...AND 12Z UPPER-AIR DATA
INDICATE THAT JEANNE IS CAUGHT IN SUCH A PATTERN. HOWEVER...ALL OF
THE GLOBAL AND REGIONAL MODELS AGREE THAT THE WESTERN PORTION OF
THE RIDGE ACROSS FLORIDA WILL GRADUALLY WEAKEN OVER THE NEXT 12-24
HOURS...WHICH SHOULD ALLOW JEANNE TO MOVE WESTWARD AT A FASTER
FORWARD SPEED. ALL OF THE MODELS ARE GENERALLY IN GOOD AGREEMENT ON
A STRONG RIDGE/HIGH CURRENTLY LOCATED OVER PENNSYLVANIA AND WEST
VIRGINIA MOVING SOUTHEASTWARD TO NEAR EASTERN NORTH CAROLINA IN
ABOUT 48-60 HOURS. HOWEVER...THERE ARE ENOUGH SUBTLE DIFFERENCES
THAT COULD DETERMINE IF...WHEN...AND WHERE JEANNE COULD MAKE
LANDFALL ALONG THE FLORIDA EAST COAST. THE ETA...NOGAPS...AND GFDN
MODELS ARE THE FARTHEST SOUTH AND BRING JEANNE ACROSS SOUTH FLORIDA
AND TO NEAR THE TAMPA BAY AREA. THE OTHER MODELS REMAIN JUST INLAND
FROM THE FLORIDA EAST COAST WITH LANDFALL BETWEEN WEST PALM BEACH
AND CAPE CANAVERAL. THE FORECAST TRACK WAS NUDGED SLIGHTLY SOUTH
AND WEST BASED ON THE GFDL...GFS...AND UKMET MODELS HAVING
INITIALIZED THE RIDGE TOO WEAK...BY ABOUT 20 METERS AT 500 MB.
USERS ARE CAUTIONED TO NOT FOCUS ON THE SPECIFIC FORECAST POINTS
DUE TO FORECAST UNCERTAINTY...THE LARGE SIZE OF THE HURRICANE...AND
BECAUSE JEANNE COULD TAKE A MORE ROUNDED PATH NEAR LANDFALL THAN
IMPLIED BY SIMPLY CONNECTING THE 48 AND 72 HOUR FORECAST POINTS. A
60-HR POINT WOULD BE CLOSE TO 26.7N 79.8W WITH A 100-KT INTENSITY.

THE SHIPS MODEL AND THE VARIOUS GLOBAL MODELS NOW INDICATE THAT
SOUTH TO SOUTHWESTERLY UPPER-LEVEL SHEAR MAY HOLD OFF UNTIL JEANNE
GETS NEAR THE FLORIDA EAST COAST IN ABOUT 60 HOURS. THIS MAY ALLOW
JEANNE TO STRENGTHEN INTO A MAJOR HURRICANE AS THE CYCLONE MOVES
OVER INCREASINGLY WARMER WATER...83-84F...LOCATED FROM THE
NORTHWEST BAHAMAS WESTWARD TO THE SOUTHEAST FLORIDA COAST.

FORECASTER STEWART

FORECAST POSITIONS AND MAX WINDS

INITIAL      23/2100Z 25.9N  70.3W    90 KT
 12HR VT     24/0600Z 25.9N  71.5W    95 KT
 24HR VT     24/1800Z 25.8N  73.4W   100 KT
 36HR VT     25/0600Z 25.8N  75.5W   105 KT
 48HR VT     25/1800Z 26.1N  77.8W   105 KT
 72HR VT     26/1800Z 27.9N  81.3W    75 KT...INLAND
 96HR VT     27/1800Z 31.5N  81.5W    55 KT...INLAND
120HR VT     28/1800Z 36.0N  77.0W    35 KT...INLAND


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