Tropical Depression ALVIN

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TROPICAL DEPRESSION ALVIN DISCUSSION NUMBER  17
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL   EP012007
800 PM PDT WED MAY 30 2007
 
LATE THIS AFTERNOON...THE LOW LEVEL CIRCULATION OF THE DEPRESSION
BECAME FULLY EXPOSED WITH VIRTUALLY NO DEEP CONVECTION REMAINING
WITHIN THE CIRCULATION.  AT THAT TIME...ALVIN COULD ALMOST HARDLY
BE CLASSIFIED AS A TROPICAL CYCLONE.  HOWEVER...JUST BEFORE 0000
UTC A NEW BURST OF CONVECTION DEVELOPED SOUTHWEST OF THE
CENTER...AND DVORAK CURRENT INTENSITY ESTIMATES FROM SAB AND TAFB
REMAIN 30 KT.  THEREFORE...ALVIN REMAINS A 30 KT TROPICAL
DEPRESSION.

ALVIN HAS CERTAINLY STRUGGLED IN ITS CURRENT ENVIRONMENT DURING THE
PAST COUPLE OF DAYS AND SINCE THE ENVIRONMENTAL CONDITIONS ARE NOT
FORECAST TO IMPROVE...IT WOULD SEEM THAT THE THE CYCLONE SHOULD
GRADUALLY WEAKEN.  THE SHIPS AND GFDL INTENSITY MODELS KEEP ALVIN'S
INTENSITY BETWEEN 25 AND 35 KT FOR THE ENTIRE FORECAST PERIOD.  IT
IS POSSIBLE THAT ALVIN WILL CONTINUE TO PRODUCE ENOUGH CONVECTION
TO REMAIN A TROPICAL CYCLONE FOR SEVERAL MORE DAYS.  HOWEVER...THE
OFFICIAL INTENSITY FORECAST WILL CONTINUE TO SHOW GRADUAL WEAKENING
WITH THE CYCLONE BECOMING A REMNANT LOW IN ABOUT 3 DAYS.

THE INITIAL MOTION ESTIMATE IS 270/3.  IT APPEARS THAT THE RIDGE
NORTH OF ALVIN HAS BEGUN TO FORCE THE CYCLONE ON A MORE WESTWARD
MOTION.  THE MODEL GUIDANCE SUGGESTS A TURN TOWARD THE SOUTHWEST 
IN A DAY OR SO AND THE OFFICIAL FORECAST FOLLOWS THIS SCENARIO. 
THE OFFICIAL FORECAST IS CLOSE TO...BUT A LITTLE SLOWER THAN...THE
PREVIOUS OFFICIAL TRACK FORECAST.
 
FORECAST POSITIONS AND MAX WINDS
 
INITIAL      31/0300Z 13.2N 115.2W    30 KT
 12HR VT     31/1200Z 13.2N 115.6W    30 KT
 24HR VT     01/0000Z 13.2N 116.4W    25 KT
 36HR VT     01/1200Z 13.1N 117.3W    25 KT
 48HR VT     02/0000Z 12.9N 118.2W    25 KT
 72HR VT     03/0000Z 12.4N 119.5W    20 KT...REMNANT LOW
 96HR VT     04/0000Z 11.5N 121.0W    20 KT...REMNANT LOW
120HR VT     05/0000Z 10.5N 122.5W    20 KT...REMNANT LOW
 
$$
FORECASTER BROWN
 
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