000 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