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TROPICAL STORM OLGA DISCUSSION NUMBER  20
NATIONAL WEATHER SERVICE MIAMI FL
11 AM AST THU NOV 29 2001

OLGA IS SHOWING SIGNS OF SHEARING THIS MORNING...WITH THE LOW-
LEVEL CENTER PARTLY EXPOSED AT THE NORTHERN EDGE OF THE DEEP
CONVECTION.  SATELLITE INTENSITY ESTIMATES ARE 65 KT FROM SAB
AND 55 KT FROM TAFB AND AFWA.  THE INITIAL INTENSITY REMAINS
55 KT FOR THIS PACKAGE.

THE INITIAL MOTION IS NOW 230/15.  SATELLITE IMAGERY INDICATES
DEEP-LAYER RIDGING TO THE NORTH AND WEST OF OLGA...AND LARGE-SCALE
MODELS INDICATE THIS SYSTEM SHOULD PERSIST FOR 24-48 HR BEFORE
WEAKENING AS A TROUGH MOVES TO THE U. S. EAST COAST.  THIS PATTERN
SHOULD KEEP OLGA ON A GENERAL SOUTHWESTWARD HEADING FOR 24 HR OR
SO...FOLLOWED BY A GRADUAL TURN TOWARD THE WEST AND DECELERATION.
ALL GUIDANCE IS IN AGREEMENT WITH THIS SCENARIO...INCLUDING THE
AVN...WHICH HAS BACKED OFF OF THE NORTHWESTWARD TURN FORECAST
EARLIER.  THE OFFICIAL FORECAST IS SIMILAR TO BUT FASTER THAN THE
PREVIOUS FORECAST.
 
WHILE OLGA IS CURRENTLY GENERATING STRONGER CONVECTION THAN AT
ANY OTHER TIME IN ITS LIFE...IT IS EXPERIENCING 20-30 KT OF SHEAR
ACCORDING TO ANALYSES BY CIMSS AT THE UNIVERSITY OF WISCONSIN.
LARGE-SCALE MODELS INDICATE THIS CONDITION SHOULD PERSIST FOR AT
LEAST 36 HR...AND OLGA SHOULD WEAKEN STEADILY DURING THIS TIME.
THE MODELS SUGGESTS THE SHEAR COULD DECREASE SOMEWHAT AFTER 36
HR...AND SHOULD THIS HAPPEN THE WEAKENING COULD BE INTERRUPTED
OR AT LEAST SLOWED AS INDICATED BY THE SHIPS MODEL.  THE INTENSITY
FORECAST WILL CALL FOR SLOW WEAKENING DURING THE 36-72 HR PERIOD.
 
FORECASTER BEVEN
 
FORECAST POSITIONS AND MAX WINDS
 
INITIAL     29/1500Z 28.1N  60.7W    60 KTS
12HR VT     30/0000Z 27.0N  62.7W    55 KTS
24HR VT     30/1200Z 26.1N  65.2W    50 KTS
36HR VT     01/0000Z 25.6N  67.6W    45 KTS
48HR VT     01/1200Z 25.5N  69.4W    40 KTS
72HR VT     02/1200Z 25.5N  71.5W    35 KTS
 
 
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