Tropical Storm JOSEPHINE

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TROPICAL STORM JOSEPHINE DISCUSSION NUMBER  11
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL   AL102008
500 PM EDT THU SEP 04 2008
 
JOSEPHINE CURRENTLY CONSISTS OF A LARGE SWIRL OF LOW/MID-LEVEL
CLOUDS THAT IS VOID OF ORGANIZED CONVECTION.  INDEED...THE ONLY
CONVECTION IN THE SYSTEM AT THIS TIME ARE A FEW CELLS WELL TO THE
SOUTHWEST AND NORTHEAST OF THE CENTER.  ANALYSES FROM CIMSS AT THE
UNIVERSITY OF WISCONSIN SHOW THAT JOSEPHINE CONTINUES TO EXPERIENCE
ABOUT 20 KT OF SOUTHWESTERLY VERTICAL WIND SHEAR.  THE INITIAL
INTENSITY IS REDUCED TO 40 KT BASED ON A BLEND OF INTENSITY
ESTIMATES FROM TAFB AND SAB...AND 35-40 KT WINDS SEEN IN AN ASCAT
PASS NEAR 12Z.
 
THE INITIAL MOTION REMAINS 285/9.  AGAIN...THERE IS NO CHANGE TO THE
FORECAST PHILOSOPHY FROM THE PREVIOUS ADVISORY.  JOSEPHINE IS
FORECAST TO MOVE IN A GENERAL WEST-NORTHWESTWARD MOTION ALONG THE
SOUTHERN PERIPHERY OF A LARGE SUBTROPICAL RIDGE FOR THE NEXT 36-48
HOURS. AFTER THAT...A WEAKNESS IS FORECAST TO DEVELOP IN THE
RIDGE...WHICH SHOULD ALLOW JOSEPHINE TO MAKE A NORTHWARD JOG AT
72-96 HR...BEFORE THE RIDGE FILLS BACK IN FORCING THE CYCLONE A
LITTLE MORE WESTWARD BY 120 HOURS.  WHILE THE GUIDANCE IS IN BETTER
AGREEMENT ON THE SPEED THIS TIME...THERE IS SOME SPREAD IN THE
DIRECTION.  THE BAMD...NOGAPS...GFDL...AND HWRF CALL FOR A
NORTHWESTERLY MOTION...WHILE THE UKMET...GFS...AND BAMS ARE AT THE
OTHER EDGE OF THE ENVELOPE CALLING FOR A WEST-NORTHWESTWARD MOTION. 
THE NEW FORECAST TRACK IS SIMILAR TO THE PREVIOUS TRACK AND LIES
ALONG THE SOUTH SIDE OF THE GUIDANCE IN BEST AGREEMENT WITH THE
UKMET AND BAMS.

THE LARGE-SCALE MODELS CONTINUE TO DISAGREE ON WHETHER THE SHEAR
OVER JOSEPHINE WILL LET UP.  THE GFS FORECASTS UPPER-LEVEL WINDS TO
BECOME MORE FAVORABLE AFTER 48 HR...WHILE THE UKMET FORECAST A
RATHER HOSTILE LOOKING UPPER-LEVEL WIND PATTERN.  IN ADDITION...THE
FORECAST TRACK TAKES THE SYSTEM OVER PROGRESSIVELY COOLER WATER FOR
60 HR BEFORE THE SEA SURFACE TEMPERATURES START INCREASING.  THE
INTENSITY FORECAST CALLS FOR A LITTLE MORE WEAKENING...THEN HOLDING
JOSEPHINE AT 35 KT THROUGH 72 HR.  THEREAFTER...IF THE GFS/
SHIPS MODELS ARE CORRECT ABOUT THE SHEAR DECREASING...SOME
RE-INTENSIFICATION IS POSSIBLE.  AN ALTERNATIVE SCENARIO...FAVORED
BY THE HWRF AND GFDN...IS THAT JOSEPHINE COULD DISSIPATE DURING THE
NEXT 5 DAYS IF THE CONVECTION DOES NOT PERSIST.
 
FORECAST POSITIONS AND MAX WINDS
 
INITIAL      04/2100Z 14.6N  33.2W    40 KT
 12HR VT     05/0600Z 14.9N  34.4W    35 KT
 24HR VT     05/1800Z 15.3N  35.9W    35 KT
 36HR VT     06/0600Z 15.8N  37.5W    35 KT
 48HR VT     06/1800Z 16.5N  39.3W    35 KT
 72HR VT     07/1800Z 18.5N  43.0W    35 KT
 96HR VT     08/1800Z 20.5N  47.0W    40 KT
120HR VT     09/1800Z 22.0N  50.5W    45 KT
 
$$
FORECASTER BEVEN
 
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