Tropical Storm JOSEPHINE

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TROPICAL STORM JOSEPHINE DISCUSSION NUMBER  10
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL   AL102008
1100 AM EDT THU SEP 04 2008
 
A QUIKSCAT OVERPASS AT 0754 UTC SHOWED A RELIABLE-LOOKING 50 KT
WIND.  HOWEVER...THE DEEP CONVECTION THAT WAS PRESENT AT THAT TIME
HAS DISSIPATED...LEAVING AN EXPOSED LOW-LEVEL CENTER WELL TO THE
SOUTHWEST OF SMALL AREAS OF DISORGANIZED CONVECTION.  BASED ON
THIS...IT IS ESTIMATED THAT JOSEPHINE HAS WEAKENED TO 45 KT.

THE INITIAL MOTION REMAINS 285/9.  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 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 ON A
LITTLE MORE WESTWARD BY 120 HOURS.  THE GUIDANCE DOES SHOW SOME
SPREAD IN THE FORWARD SPEED...WITH THE UKMET BEING THE
SLOWEST...THE GFDL AND HWRF BEING THE FASTEST...AND THE OTHER
MODELS IN BETWEEN.  THE NEW FORECAST TRACK COMPROMISES IN SPEED
BETWEEN THE GFDL/HWRF AND THE MODEL CONSENSUS...BUT IS SLOWER THAN
THE PREVIOUS ADVISORY.  THE TRACK CONTINUES ALONG THE SOUTHERN EDGE
OF THE GUIDANCE ENVELOPE.

JOSEPHINE CONTINUES TO EXPERIENCE 20-25 KT OF SOUTHWESTERLY VERTICAL
WIND SHEAR DUE TO THE LARGE UPPER-LEVEL TROUGH TO ITS NORTHWEST.  
THE SHEAR IS FORECAST TO CONTINUE FOR 36-48 HR WHILE JOSEPHINE
MOVES OVER SLIGHTLY COOLER SEA SURFACE TEMPERATURES.  ON THIS
BASIS... THE NEW INTENSITY FORECAST CALLS FOR A LITTLE MORE
WEAKENING...THEN MAINTAINS A 40 KT INTENSITY THROUGH 72 HR.  SOME
FLUCTUATIONS IN STRENGTH COULD OCCUR DURING THIS TIME DUE TO
CONVECTIVE BURSTS.  AFTER 72 HR...THE SHEAR MAY DECREASE...ALTHOUGH
THE LARGE-SCALE MODELS DO NOT AGREE ON THIS.  ON THE BASIS THAT THE
SHEAR DECREASES AS JOSEPHINE REACHES WARMER WATERS...THE FORECAST
CALLS FOR SLIGHT INTENSIFICATION.  THE INTENSITY FORECAST IS IN
BEST AGREEMENT WITH THE SHIPS MODEL... ALTHOUGH IT IS ABOVE ALL THE
INTENSITY GUIDANCE EXCEPT SHIFOR.
 
 
FORECAST POSITIONS AND MAX WINDS
 
INITIAL      04/1500Z 14.5N  32.2W    45 KT
 12HR VT     05/0000Z 14.9N  33.5W    40 KT
 24HR VT     05/1200Z 15.3N  35.2W    40 KT
 36HR VT     06/0000Z 15.8N  36.7W    40 KT
 48HR VT     06/1200Z 16.4N  38.3W    40 KT
 72HR VT     07/1200Z 18.0N  42.0W    40 KT
 96HR VT     08/1200Z 20.0N  46.0W    45 KT
120HR VT     09/1200Z 21.5N  50.0W    50 KT
 
$$
FORECASTER BEVEN
 
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