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HURRICANE OCTAVE DISCUSSION NUMBER 9
NATIONAL WEATHER SERVICE MIAMI FL
8 PM PDT THU NOV 01 2001
HURRICANE OCTAVE HAS RAPIDLY STRENGTHENED DURING THE PAST 6 HOURS
BASED ON A DVORAK SATELLITE INTENSITY ESTIMATE OF T4.5...77 KT...
FROM BOTH TAFB AND SAB. THEREFORE...THE INITIAL INTENSITY HAS BEEN
INCREASED TO 75 KT. UPPER-LEVEL OUTFLOW REMAINS GOOD TO THE NORTH
...BUT IS BECOMING LESS DISTINCT TO THE SOUTH.
THE INITIAL MOTION ESTIMATE IS 340/08. OCTAVE HAS STAYED ON TRACK
SO THERE IS NO SIGNIFICANT CHANGE TO THE PREVIOUS FORECAST TRACK OR
REASONING. THE HURRICANE SHOULD CONTINUE TO TRACK NORTHWARD THROUGH
A WEAKNESS IN THE MID-LEVEL SUBTROPICAL RIDGE. THE BIGGEST QUESTION
IS WHETHER OR NOT OCTAVE WILL BECOME SHEARED BEFORE IT REACHES A
WEAK COLD FRONT THAT IS APPROACHING FROM THE NORTH. IF THE SYSTEM
REMAINS VERTICALLY DEEP...THEN IT COULD STILL RECURVE A LITTLE TO
THE NORTHEAST BEFORE IT WEAKENS OVER COLD WATER AND BENEATH
INCREASING SOUTHWESTERLY UPPER-LEVEL SHEAR. THE OFFICIAL TRACK IS
CLOSE TO THE AVN MODEL...WHICH HAS BEEN HANDLING THIS SYSTEM QUITE
WELL. THE NOGAPS AND UKMET MODELS APPEAR TO BE OUTLIERS IN TAKING
THE CYCLONE WESTWARD...WHICH IS NOT UNUSUAL FOR THESE MODELS TO DO
WITH SMALL COMPACT SYSTEMS LIKE OCTAVE.
THERE IS NO CHANGE TO THE PREVIOUS INTENSITY FORECAST OR REASONING.
OCTAVE HAS LIKELY PEAKED IN INTENSITY...AND COOLER WATER AND
INCREASING VERTICAL SHEAR AHEAD OF THE CYCLONE SHOULD BRING ABOUT
STEADY WEAKENING. THE SHIPS INTENSITY MODEL WAS FOLLOWED CLOSELY...
EXCEPT AT 72 HOURS WHEN IT DISSIPATES OCTAVE.
FORECASTER STEWART
FORECAST POSITIONS AND MAX WINDS
INITIAL 02/0300Z 16.8N 128.7W 75 KTS
12HR VT 02/1200Z 17.8N 128.9W 70 KTS
24HR VT 03/0000Z 18.9N 129.0W 60 KTS
36HR VT 03/1200Z 19.8N 129.0W 55 KTS
48HR VT 04/0000Z 20.6N 129.1W 50 KTS
72HR VT 05/0000Z 21.5N 129.5W 35 KTS
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