Tropical Storm KEVIN

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TROPICAL STORM KEVIN DISCUSSION NUMBER   7
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL   EP142009
800 PM PDT SUN AUG 30 2009
 
VISIBLE AND INFRARED SATELLITE IMAGERY INDICATES THAT KEVIN CONSISTS
OF A SHAPELESS MASS OF CONVECTION...WHICH IS DISPLACED NORTHWEST OF
THE CENTER BY MODERATE SOUTHEASTERLY SHEAR. AN EARLIER ASCAT
OVERPASS REVEALED A SMALL AREA OF UNCONTAMINATED 25-30 KT WIND
VECTORS JUST NORTHWEST OF THE CENTER...WITH WEAKER WINDS IN THE
EASTERN SEMICIRCLE. DVORAK CI-NUMBERS AT 0000 UTC WERE 2.5 AND 3.0
FROM TAFB AND SAB...RESPECTIVELY. BASED UPON THE EARLIER ASCAT
PASS...DVORAK INTENSITY ESTIMATES...AND A GRADUALLY DETERIORATING
CLOUD PATTERN...THE INITIAL INTENSITY ESTIMATE IS LOWERED TO 35 KT.
THE INTENSITY GUIDANCE IS UNANIMOUS IN PREDICTING A CONTINUED
WEAKENING OF KEVIN OVER THE NEXT COUPLE OF DAYS...EVEN THOUGH THE
SHEAR APPEARS LOW AND THE WATERS SUFFICIENTLY WARM. THE KEY TO THE
WEAKENING APPEARS TO BE RELATED TO A MORE STABLE BOUNDARY LAYER AND
RELATIVELY DRY CONDITIONS IN THE LOW- TO MID-LEVELS. THE OFFICIAL
INTENSITY FORECAST CALLS FOR GRADUAL WEAKENING TO A REMNANT LOW BY
DAY 4...IS IN LINE WITH THE PREVIOUS ADVISORY AND CLOSE TO THE
INTENSITY MODEL CONSENSUS.
 
KEVIN IS MOVING GENERALLY NORTHWARD...WITH THE LATEST MOTION
ESTIMATED AT 005/06. THE CYCLONE IS EMBEDDED IN A WEAK STEERING
ENVIRONMENT...SANDWICHED BETWEEN A DEEP-LAYER RIDGE TO THE
SOUTHEAST AND A MID- TO UPPER-LEVEL TROUGH DANGLING WEST-
SOUTHWESTWARD FROM THE SOUTHERN BAJA CALIFORNIA PENINSULA. THESE
TWO FEATURES WILL CAUSE A NORTH-NORTHEAST TO NORTHEAST MOTION FOR
THE NEXT FEW DAYS...ALBEIT IT FAIRLY SLOW. THE OFFICIAL TRACK
FORECAST WAS ADJUSTED SLIGHTLY TO THE LEFT OF THE PREVIOUS TRACK TO
ACCOUNT FOR A PERSISTENT NORTHERLY INITIAL MOTION BUT REMAINS IN
GOOD AGREEMENT WITH THE MODEL CONSENSUS. 
 
FORECAST POSITIONS AND MAX WINDS
 
INITIAL      31/0300Z 16.4N 121.7W    35 KT
 12HR VT     31/1200Z 16.9N 121.4W    35 KT
 24HR VT     01/0000Z 17.6N 120.6W    30 KT
 36HR VT     01/1200Z 18.3N 119.9W    30 KT
 48HR VT     02/0000Z 18.9N 119.1W    30 KT
 72HR VT     03/0000Z 19.5N 119.0W    25 KT
 96HR VT     04/0000Z 20.0N 119.0W    20 KT...REMNANT LOW
120HR VT     05/0000Z 20.5N 119.0W    20 KT...REMNANT LOW
 
$$
FORECASTER KIMBERLAIN
 
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