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TROPICAL STORM OCTAVE DISCUSSION NUMBER 5
NATIONAL WEATHER SERVICE MIAMI FL
8 PM PDT WED OCT 31 2001
BANDING FEATURES HAVE CONTINUED TO IMPROVE AND OCTAVE IS BEGINNING
TO LOOK MORE LIKE A HURRICANE. HOWEVER...THE CENTRAL DEEP
CONVECTION IS STILL SOMEWHAT WEAK AND DISORGANIZED. THE INITIAL
INTENSITY OF 50 KT IS BASED ON A BLEND OF DVORAK SATELLITE INTENSITY
ESTIMATES OF 55 KT FROM SAB AND 35 KT FROM TAFB...AND THE IMPRESSIVE
BANDING FEATURES AS SEEN IN VISIBLE SATELLITE IMAGERY.
THE INITIAL MOTION ESTIMATE IS 310/11. WATER VAPOR IMAGERY
CONTINUES TO INDICATE A MID- TO UPPER-LEVEL RIDGE TO THE NORTHEAST
OF OCTAVE...WITH A WEAKNESS IN THE RIDGE AXIS TO THE NORTH AND
NORTHWEST OF THE CYCLONE. THE ONLY NHC MODEL THAT RECURVES THE
STORM IS THE LBAR MODEL. THE REMAINDER OF THE MODEL GUIDANCE TAKE
THE STORM NORTHWARD OR NORTHWESTWARD. THE EXCEPTION IS THE UKMET
MODEL...WHICH TAKES OCTAVE WESTWARD. THIS SCENARIO WAS DISCOUNTED
SINCE THE UKMET KEEPS THE CYCLONE VERY WEAK AND...AS A RESULT...
DRIVES IT WESTWARD UNDER THE INFLUENCE OF THE MODERATE LOW-LEVEL
EASTERLY FLOW TO THE NORTH OF THE STORM. THE OFFICIAL FORECAST IS
ALMOST ON TOP OF THE PREVIOUS FORECAST TRACK AND IS BETWEEN THE GFDL
AND AVN MODEL SOLUTIONS.
OCTAVE POSSESSES GOOD UPPER-LEVEL OUTFLOW...WHICH CONTINUES TO
IMPROVE. GIVEN THE IMPRESSIVE BANDING FEATURES AND DECREASING
SHEAR...ADDITIONAL STRENGTHENING FOR AT LEAST 24 TO PERHAPS 36 HOURS
SEEMS TO BE IN ORDER. BY 36 HOURS...SOUTHWESTERLY UPPER-LEVEL SHEAR
BEGINS TO INCREASE AND THIS...COMBINED WITH COOLER SSTS...SHOULD
BRING ABOUT A SIGNIFICANT WEAKENING TREND. THE SHIPS INTENSITY
MODEL WAS FOLLOWED CLOSELY...WHICH BRINGS OCTAVE TO NEAR HURRICANE
STRENGTH IN 24 HOURS.
FORECASTER STEWART
FORECAST POSITIONS AND MAX WINDS
INITIAL 01/0300Z 14.6N 127.4W 50 KTS
12HR VT 01/1200Z 15.5N 128.1W 55 KTS
24HR VT 02/0000Z 16.7N 128.7W 60 KTS
36HR VT 02/1200Z 18.0N 129.0W 65 KTS
48HR VT 03/0000Z 19.1N 129.0W 55 KTS
72HR VT 04/0000Z 21.0N 129.0W 40 KTS
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