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Tropical Storm ALVIN (Text)

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TROPICAL STORM ALVIN DISCUSSION NUMBER  11
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL   EP012007
800 AM PDT TUE MAY 29 2007
 
DVORAK INTENSITY ESTIMATES FROM TAFB AND SAB WERE 35 KT AT 12Z.
MICROWAVE IMAGES ARE NOT CONCLUSIVE...BUT SUGGEST THE CENTER OF
ALVIN IS BECOMING MORE EMBEDDED WITHIN THE DEEP CONVECTION...WHICH
EACH DAY HAS BECOME MORE PERSISTENT THAN THE DAY BEFORE.  GIVEN
THIS...AND SINCE THE SHEAR IS MODERATE AND THE WATERS ARE
WARM...SOME INTENSIFICATION WOULD SEEM TO BE IN ORDER.  NEITHER THE
SHIPS NOR THE GFDL TAKE ALVIN HIGHER THAN A MID-RANGE TROPICAL
STORM...PRESUMABLY DUE TO THERMODYNAMIC FACTORS.  THE CURRENT
CONVECTIVE TRENDS...HOWEVER...MAY INDICATE THAT ALVIN IS BEGINNING
TO CHIP AWAY AT ITS STABLE ENVIRONMENT.  THE OFFICIAL FORECAST
ALLOWS FOR JUST A LITTLE MORE DEVELOPMENT THAN THE SHIPS AND GFDL
GUIDANCE.
 
THE INITIAL MOTION ESTIMATE IS 260/3.  THERE HAS BEEN NO CHANGE TO
THE TRACK FORECAST PHILOSOPHY...WHICH CALLS FOR ALVIN TO CONTINUE
WESTWARD ALONG THE SOUTHERN SIDE OF A MID-LEVEL SUBTROPICAL RIDGE.
THE ECMWF HAS DONE A NICE JOB WITH ALVIN SO FAR.  THE OFFICIAL
FORECAST IS CLOSE TO THE PREVIOUS ADVISORY AND A BLEND OF THE
GFDL...ECMWF...AND NOGAPS.

 
FORECAST POSITIONS AND MAX WINDS
 
INITIAL      29/1500Z 12.6N 114.2W    35 KT
 12HR VT     30/0000Z 12.5N 114.8W    40 KT
 24HR VT     30/1200Z 12.4N 115.6W    45 KT
 36HR VT     31/0000Z 12.4N 116.8W    50 KT
 48HR VT     31/1200Z 12.5N 117.9W    45 KT
 72HR VT     01/1200Z 12.5N 119.5W    45 KT
 96HR VT     02/1200Z 12.5N 120.5W    40 KT
120HR VT     03/1200Z 12.5N 121.5W    35 KT
 
$$
FORECASTER FRANKLIN
 
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