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TROPICAL STORM OLIVIA DISCUSSION NUMBER 24
NATIONAL WEATHER SERVICE MIAMI FL
2 AM PDT SUN OCT 08 2000
A TRMM OVERPASS AT 0221Z...COURTESY OF THE NRL WEB PAGE...SHOWS THAT
OLIVIA REMAINS IN A STRONGLY SHEARED STATE. CONVECTION HAS BEEN
VIGOROUS...BUT IS ABOUT 60 NM TO THE WEST OF THE LOW-LEVEL
CIRCULATION CENTER. SATELLITE DVORAK CI NUMBERS FROM TAFB AND SAB
GIVE 65 AND 55 KT RESPECTIVELY. EVEN THE T NUMBER INTENSITIES...55
AND 45 KT...ARE OVERLY GENEROUS IF THE TRMM POSITION IS CORRECT.
THE ADVISORY INTENSITY IS LOWERED TO 45 KT AND IS PROBABLY HIGH. A
RECENT QUIKSCAT PASS CAUGHT THE EAST SIDE AND SHOWED NOTHING ABOVE
ABOUT 30 KT.
THE INITIAL MOTION ESTIMATE IS 310/09. GLOBAL MODELS SHOW A BREAK
IN THE MID-TROPOSPHERIC RIDGE JUST AHEAD OF OLIVIA...AND WATER VAPOR
IMAGERY SHOWS A SLOW-MOVING MID- TO UPPER-LEVEL SHORT-WAVE TROUGH
NEAR 28N124W. THESE FEATURES SHOULD TURN OLIVIA TO THE NORTH IN 24-
36 HOURS. AFTER THAT...A MAJOR TROUGH IS FORECAST BY BOTH THE AVN
AND UKMET TO DIG DOWN AND ACCELERATE OLIVIA NORTHEASTWARD. MODEL
GUIDANCE IS IN VERY GOOD AGREEMENT ALTHOUGH THE AMOUNT OF
ACCELERATION IS IN QUESTION. THE OFFICIAL FORECAST IS A LITTLE
FASTER THAN THE PREVIOUS ADVISORY AND IS CLOSE TO THE UKMET AND
GFDL.
ALTHOUGH THE SHIPS INTENSITY GUIDANCE FORECASTS A GRADUAL
WEAKENING...THERE WOULD SEEM TO BE A WINDOW OF OPPORTUNITY FOR
OLIVIA TO STRENGTHEN IN ABOUT 24-36 HOURS AS IT MOVES UNDER THE 200
MB RIDGE AXIS WHEN THERE SHOULD BE A REDUCTION IN THE STRONG
EASTERLY SHEAR. SHOULD THIS OCCUR...THEN OLIVIA COULD HOLD TOGETHER
AS A TROPICAL STORM UNTIL IT REACHES THE BAJA PENINSULA.
FORECASTER FRANKLIN
FORECAST POSITIONS AND MAX WINDS
INITIAL 08/0900Z 18.3N 113.5W 45 KTS
12HR VT 08/1800Z 19.2N 114.6W 45 KTS
24HR VT 09/0600Z 20.4N 115.7W 45 KTS
36HR VT 09/1800Z 21.7N 116.2W 50 KTS
48HR VT 10/0600Z 23.5N 115.5W 45 KTS
72HR VT 11/0600Z 27.5N 112.0W 40 KTS
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