Tropical Storm ISIS
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TROPICAL STORM ISIS DISCUSSION NUMBER 10
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
8 AM PDT FRI SEP 10 2004
THERE HAS BEEN A MARKED DECREASE IN DEEP CONVECTION WITH ISIS THIS
MORNING. I AM A LITTLE PUZZLED AS TO WHY...SINCE THE SSTS ARE
STILL AROUND 27C AND THE SHEAR DOES NOT APPEAR TO HAVE INCREASED
ANY. DVORAK T NUMBERS ARE BEGINNING TO DECREASE...BUT THE MOST
RECENT QUIKSCAT PASS SUGGESTS THAT WINDS ARE STILL AROUND 40 KT.
GLOBAL MODELS CONTINUE TO FORECAST A LESSENING OF THE SHEAR...BUT
THIS IS CLEARLY NOT HAPPENING AS QUICKLY AS EXPECTED. THE OFFICIAL
FORECAST INTENSITY IS LOWERED ONLY A BIT FROM THE PREVIOUS ADVISORY
IN DEFERENCE TO BOTH THE SHIPS AND GFDL GUIDANCE...WHICH CONTINUE
TO SHOW STRENGTHENING...BUT IF THE SHEAR DOES NOT LESSEN VERY SOON
A WEAKENING TREND WILL COMMENCE MORE QUICKLY THAN INDICATED BELOW.
A NICE MICROWAVE PASS AT 08Z HELPS ESTABLISH THE INITIAL MOTION
ESTIMATE AT 270/8. ISIS IS SOUTH OF A DEEP-LAYER RIDGE THAT IS
FORECAST TO PERSIST THROUGH THE FORECAST PERIOD. MODEL GUIDANCE IS
TIGHTLY CLUSTERED ON A WESTERLY TRACK WITH A GRADUAL INCREASE IN
FORWARD SPEED. THE OFFICIAL FORECAST ESSENTIALLY JUST UPDATES THE
PREVIOUS TRACK.
FORECASTER FRANKLIN
FORECAST POSITIONS AND MAX WINDS
INITIAL 10/1500Z 17.3N 116.2W 40 KT
12HR VT 11/0000Z 17.5N 117.7W 40 KT
24HR VT 11/1200Z 18.0N 120.0W 45 KT
36HR VT 12/0000Z 18.6N 122.6W 45 KT
48HR VT 12/1200Z 19.0N 125.5W 45 KT
72HR VT 13/1200Z 19.0N 131.0W 45 KT
96HR VT 14/1200Z 19.0N 137.0W 40 KT
120HR VT 15/1200Z 19.0N 144.0W 40 KT
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