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Tropical Storm ALVIN (Text)

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TROPICAL STORM ALVIN DISCUSSION NUMBER  10
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL   EP012007
200 AM PDT TUE MAY 29 2007
 
ALVIN DOES NOT APPEAR SIGNIFICANTLY DIFFERENT IN SATELLITE IMAGERY
THIS MORNING WITH MUCH OF THE DEEP CONVECTION REMAINING SOUTH OF
THE LOW-LEVEL CIRCULATION.  THIS PATTERN IS SOMEWHAT
COUNTERINTUITIVE GIVEN THE SOUTHEASTERLY SHEAR CURRENTLY IMPACTING
THE CYCLONE.  IT MAY BE THAT CONVECTION IS SIMPLY FAVORING THE
BETTER THERMODYNAMIC ENVIRONMENT TO THE SOUTH. REGARDLESS...ALVIN
DOES NOT APPEAR TO BE STRENGTHENING...AND THE INITIAL INTENSITY OF
35 KT IS UNCHANGED FROM THE PREVIOUS ADVISORY.  ATMOSPHERIC
CONDITIONS ARE NOT FORECAST TO IMPROVE SO SIGNIFICANT
INTENSIFICATION SEEMS UNLIKELY.  THE ONLY FACTOR FAVORING
INTENSIFICATION IS THE CYCLONE'S EXPECTED TRACK OVER 28C WATER
DURING THE NEXT COUPLE OF DAYS.  THE OFFICIAL INTENSITY FORECAST
REFLECTS A COMPROMISE BETWEEN OCEANIC AND ATMOSPHERIC FORCING AND
SHOWS ALVIN REACHING 45 KT DURING THE MIDDLE OF THE FORECAST PERIOD
FOLLOWED BY SLOW WEAKENING THEREAFTER.  THIS FORECAST IS CONSISTENT
WITH THE INTENSITY CONSENSUS ICON.
 
WHILE THE CENTER OF ALVIN REMAINS ELUSIVE IN SATELLITE IMAGERY...THE
OVERALL CLOUD MASS CONTINUES TO MOVE SLOWLY WEST-SOUTHWESTWARD.
ACCORDINGLY...THE INITIAL MOTION ESTIMATE IS 250/5 IN LINE WITH THE
PREVIOUS ADVISORY MOTION AND TRACK. THE TRACK FORECAST PHILOSOPHY
REMAINS UNCHANGED.  THE PRIMARY SYNOPTIC STEERING WILL CONTINUE TO
BE A MID-LEVEL RIDGE CURRENTLY SITUATED TO THE NORTHWEST OF THE
CYCLONE. THIS RIDGE IS EXPECTED TO SHIFT NORTHEASTWARD OVER THE
NEXT SEVERAL DAYS.  UNDER THIS REGIME...ALVIN SHOULD MOVE GENERALLY
WESTWARD DURING THE FORECAST PERIOD.  THE ONE POTENTIAL CAVEAT IS
THE DISPLACEMENT OF THE DEEP CONVECTION TO THE SOUTH OF THE
LOW-LEVEL CIRCULATION.  AS LONG AS THIS PATTERN PERSISTS...THE
CENTER WILL BE PULLED A LITTLE SOUTH OF DUE WEST. THE OFFICIAL
TRACK FORECAST REFLECTS THIS REASONING AND IS MERELY AN UPDATE OF
THE PREVIOUS ADVISORY.
 
FORECAST POSITIONS AND MAX WINDS
 
INITIAL      29/0900Z 12.5N 114.0W    35 KT
 12HR VT     29/1800Z 12.3N 114.6W    35 KT
 24HR VT     30/0600Z 12.2N 115.7W    40 KT
 36HR VT     30/1800Z 12.2N 116.7W    45 KT
 48HR VT     31/0600Z 12.2N 117.5W    45 KT
 72HR VT     01/0600Z 12.2N 119.0W    45 KT
 96HR VT     02/0600Z 12.2N 120.5W    40 KT
120HR VT     03/0600Z 12.2N 121.5W    40 KT
 
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