704 
 WTPZ45 KNHC 142031
 TCDEP5
 TROPICAL STORM ISELLE DISCUSSION NUMBER   6
 NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL   EP102008
 200 PM PDT THU AUG 14 2008
  
 TROPICAL STORM ISELLE HAS WEAKENED AS NORTHEASTERLY VERTICAL WIND
 SHEAR HAS INCREASED ACROSS THE CYCLONE. THE ADVISORY INTENSITY IS
 BASED ON A CONSENSUS SATELLITE INTENSITY ESTIMATE OF 40 KT FROM
 TAFB AND SAB.
  
 TROPICAL STORM ISELLE HAS MADE A SLIGHT JOG TO THE WEST DURING THE
 PAST 6 HOURS...BUT THIS MAY BE A TEMPORARY MOTION DUE TO THE
 EARLIER WEAKENING OF THE INNER-CORE CONVECTION. HOWEVER...
 CONVECTION IN THE SOUTHWESTERN QUADRANT HAS REDEVELOPED...SO A TURN
 TO THE WEST-NORTHWEST IS EXPECTED TO RESUME AND CONTINUE FOR THE
 NEXT 48 HOURS OR SO. AFTERWARD...A SHALLOW TROPICAL DEPRESSION OR
 REMNANT LOW IS FORECAST TO TURN WESTWARD AS THE CIRCULATION GETS
 STEERED BY THE LOW-LEVEL EASTERLIES NORTH OF THE SYSTEM...AND ALSO
 POSSIBLY DUE TO INTERACTION WITH A LARGER CYCLONIC GYRE SITUATED TO
 THE WEST-SOUTHWEST OF ISELLE. ALL OF THE NHC MODEL GUIDANCE NOW
 SUPPORTS THIS SCENARIO AND THERE ARE NO LONGER ANY MODELS THAT TAKE
 ISELLE TOWARD SOUTHERN BAJA CALIFORNIA. THE OFFICIAL FORECAST TRACK
 IS SOUTH OF THE PREVIOUS TRACK AND IS SIMILAR TO THE NHC MODEL
 CONSENSUS.
  
 HOSTILE VERTICAL WIND SHEAR CONDITIONS OF 25 TO 30 KT THROUGH 96
 HOURS ARE FORECAST TO PERSIST...AND THESE UNFAVORABLE UPPER-LEVEL
 CONDITIONS...COMBINED WITH STEADILY DECREASING SEA-SURFACE
 TEMPERATURES...ARE EXPECTED TO CAUSE GRADUAL WEAKENING OF THE
 CYCLONE THROUGHOUT THE FORECAST CYCLE WITH ISELLE POSSIBLY BECOMING
 A NON-CONVECTIVE LOW PRESSURE SYSTEM BY 72-96 HOURS. THE OFFICIAL
 INTENSITY FORECAST IS SIMILAR TO THE SHIPS INTENSITY MODEL.
  
 
 FORECAST POSITIONS AND MAX WINDS
  
 INITIAL      14/2100Z 17.8N 110.2W    40 KT
  12HR VT     15/0600Z 18.3N 111.2W    40 KT
  24HR VT     15/1800Z 18.9N 112.4W    35 KT
  36HR VT     16/0600Z 19.5N 113.5W    35 KT
  48HR VT     16/1800Z 19.8N 114.5W    30 KT
  72HR VT     17/1800Z 20.0N 116.0W    30 KT
  96HR VT     18/1800Z 20.0N 117.5W    25 KT
 120HR VT     19/1800Z 20.0N 119.0W    20 KT
  
 $$
 FORECASTER STEWART/PASCH