031 
 WTNT45 KNHC 021450
 TCDAT5
 TROPICAL STORM JOSEPHINE DISCUSSION NUMBER   2
 NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL   AL102008
 1100 AM EDT TUE SEP 02 2008
  
 VISIBLE IMAGERY REVEALS AN INCREASE IN THE CYCLONE'S
 ORGANIZATION...WITH VERY WELL-DEFINED CONVECTIVE BANDS AND EVEN A
 DECEPTIVE CENTRAL FEATURE DISGUISED AS AN EYE.  THE CONVECTIVE TOPS
 ARE NOT EXCEPTIONALLY COLD IN THE INFRARED...BUT DVORAK INTENSITY
 ESTIMATES ARE A CONSENSUS 35 KT...SO THE DEPRESSION IS UPGRADED TO
 A TROPICAL STORM...THE TENTH OF THE 2008 ATLANTIC SEASON. 
 JOSEPHINE IS CURRENTLY OVER SEA-SURFACE TEMPERATURES OF ABOUT 28
 CELSIUS...AND THE WATERS ALONG THE FORECAST TRACK WILL REMAIN AT
 LEAST THAT WARM FOR ABOUT THE NEXT 24 HOURS.  WIND SHEAR IS
 ESSENTIALLY NON-EXISTENT OVER THE CYCLONE...SO STEADY STRENGTHENING
 SEEMS LIKELY IN THE SHORT TERM...AND COULD BE RAPID GIVEN THE
 INCREASED ORGANIZATION AND THAT THE SHIPS-BASED RI INDEX GIVES A
 50% CHANCE OF AN INTENSITY INCREASE OF 30 KT OR MORE IN THE NEXT 24
 HOURS.  BEYOND 24 HOURS...JOSEPHINE WILL TRAVERSE SLIGHTLY COOLER
 WATERS...AND DUE TO AN UPPER-LEVEL LOW FORECAST BY THE MODELS TO
 MOVE IN TANDEM WITH THE TROPICAL CYCLONE...WIND SHEAR WILL PROBABLY
 INCREASE IN A COUPLE OF DAYS.  EVEN THOUGH ALL OF THE OBJECTIVE
 GUIDANCE CALLS FOR A WEAKENING TREND TO START BY 72 HOURS...TO
 MAINTAIN SOME CONTINUITY THE NEW OFFICIAL INTENSITY FORECAST SIMPLY
 SHOWS AN INTENSITY PLATEAU AT 60 KT IN THE LONGER TERM.
 
 THE INITIAL MOTION REMAINS BRISK ALONG A HEADING JUST NORTH OF DUE
 WEST...OR 280/13...BUT THE INITIAL POSITION HAS BEEN ADJUSTED
 SLIGHTLY NORTH OF THE PREVIOUS TRACK BASED ON VISIBLE IMAGERY AND
 AN EARLIER QUIKSCAT PASS.  A MID-LEVEL HIGH CENTERED OVER THE
 EAST-CENTRAL SUBTROPICAL ATLANTIC IS CURRENTLY THE PRIMARY STEERING
 MECHANISM...BUT THIS FEATURE IS FORECAST BY THE MODELS TO PROCEED
 WESTWARD AND SHIFT TO THE WESTERN ATLANTIC IN A FEW DAYS. 
 MEANWHILE...THE DEEP-LAYER LOW JUST OFF THE NORTHEASTERN UNITED
 STATES WILL PROPAGATE EASTWARD AND ERODE THE RIDGE NORTH OF
 JOSEPHINE...WHICH WILL PROBABLY JUST CAUSE A SLIGHT BEND TO THE
 RIGHT AND A SLOWER FORWARD MOTION AT DAYS 3-5.  MODELS ARE IN VERY
 GOOD AGREEMENT THROUGH 48 HOURS BUT THEN DIVERGE MARKEDLY...WITH
 THE GFS TURNING THE CYCLONE WESTWARD AND THE GFDL AND HWRF TAKING
 IT NORTHWESTWARD.  THE OFFICIAL TRACK FORECAST SPLITS THE
 DIFFERENCE AND FOLLOWS THE CONSENSUS...WHICH IS JUST A LITTLE NORTH
 OF THE PREVIOUS ADVISORY.
  
 FORECAST POSITIONS AND MAX WINDS
  
 INITIAL      02/1500Z 13.2N  25.3W    35 KT
  12HR VT     03/0000Z 13.6N  27.4W    45 KT
  24HR VT     03/1200Z 14.3N  29.9W    55 KT
  36HR VT     04/0000Z 15.2N  32.4W    60 KT
  48HR VT     04/1200Z 16.1N  34.9W    60 KT
  72HR VT     05/1200Z 18.5N  39.5W    60 KT
  96HR VT     06/1200Z 20.0N  43.5W    60 KT
 120HR VT     07/1200Z 21.0N  47.0W    60 KT
  
 $$
 FORECASTER KNABB