897 
 WTPZ45 KNHC 150846
 TCDEP5
 TROPICAL STORM ISELLE DISCUSSION NUMBER   8
 NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL   EP102008
 200 AM PDT FRI AUG 15 2008
  
 CONVECTION CONTINUES TO GRADUALLY DECREASE IN BOTH COVERAGE AND
 DEPTH.  AN ASCAT OVERPASS AT ABOUT 05Z RETRIEVED WINDS OF ABOUT 35
 KT IN THE EASTERN SEMICIRCLE OF THE CIRCULATION...AND WHILE THOSE
 VALUES COULD HAVE BEEN SLIGHT UNDERESTIMATES THAT ARE COMMON WITH
 THAT INSTRUMENT...THE WEAKENING CONVECTION SUGGESTS THE WINDS HAVE
 PROBABLY COME DOWN SINCE THEN.  THE ADVISORY INTENSITY IS LOWERED
 SLIGHTLY TO 35 KT...WHICH IS CONSISTENT WITH THE LATEST SUBJECTIVE
 DVORAK CI NUMBERS FROM TAFB AND SAB.  EASTERLY SHEAR IS TAKING ITS
 TOLL ON ISELLE AND IS FORECAST BY THE DYNAMICAL MODELS TO GET A
 LITTLE STRONGER AND PERSIST THROUGHOUT THE FIVE-DAY FORECAST
 PERIOD.  AS A RESULT...DESPITE RELATIVELY WARM SEA-SURFACE
 TEMPERATURES ALONG THE FORECAST TRACK FOR THE NEXT 2-3 DAYS...ALL OF
 THE OBJECTIVE INTENSITY GUIDANCE FORECASTS STEADY WEAKENING...AND
 SO DOES THE OFFICIAL FORECAST.  THE CYCLONE COULD DEGENERATE INTO A
 REMNANT LOW AT JUST ABOUT ANY TIME WITHIN THE NEXT COUPLE OF DAYS.
 
 MIDDLE- AND UPPER-LEVEL RIDGING CENTERED OVER NORTHWESTERN MEXICO IS
 STEERING ISELLE TOWARD THE WEST OR ABOUT 270/7.  AS THE CYCLONE
 WEAKENS...IT OR WHATEVER IS LEFT OF IT WILL CONTINUE GENERALLY
 WESTWARD BUT PROBABLY SLOW DOWN...SINCE IT WILL REMAIN WELL EAST OF
 THE MAIN BELT OF LOW-LEVEL EASTERLY TRADES.  THE NEW OFFICIAL TRACK
 FORECAST IS A LITTLE SOUTH OF THE PREVIOUS ONE AND IS GENERALLY A
 BLEND OF THE NOGAPS AND UKMET.
  
  
 FORECAST POSITIONS AND MAX WINDS
  
 INITIAL      15/0900Z 17.7N 111.7W    35 KT
  12HR VT     15/1800Z 17.9N 112.6W    30 KT
  24HR VT     16/0600Z 18.3N 113.8W    30 KT
  36HR VT     16/1800Z 18.5N 114.8W    25 KT...REMNANT LOW
  48HR VT     17/0600Z 18.5N 115.7W    25 KT...REMNANT LOW
  72HR VT     18/0600Z 18.5N 117.5W    20 KT...REMNANT LOW
  96HR VT     19/0600Z 18.5N 119.0W    20 KT...REMNANT LOW
 120HR VT     20/0600Z 18.5N 120.5W    20 KT...REMNANT LOW
  
 $$
 FORECASTER KNABB