Tropical Storm ADRIAN

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TROPICAL STORM ADRIAN DISCUSSION NUMBER  17
NWS NATIONAL HURRICANE CENTER MIAMI FL       EP012011
800 AM PDT SAT JUN 11 2011
 
THE RAPID WEAKENING OF ADRIAN CONTINUES AS THE CONVECTIVE
ORGANIZATION IS DEVOLVING TOWARD A SHEAR PATTERN.  THE
DECREASE IN INTENSITY IS LIKELY DUE TO AN UNEXPECTEDLY EARLY
INCREASE OF VERTICAL SHEAR COUPLED WITH MARGINAL THERMODYNAMICS. 
WHILE THE SUBJECTIVE DVORAK AND THE ADVANCED DVORAK TECHNIQUES BOTH
ARE RULE-CONSTRAINED TO INDICATE HURRICANE INTENSITY...THE AMSU
INTENSITY ESTIMATES FROM CIMSS AND CIRA ARE MUCH WEAKER.  A BLEND
OF THESE ARE THE BASIS FOR THE 60 KT INTENSITY AT ADVISORY
TIME...AND THAT COULD BE GENEROUS. WITH ADRIAN DROPPING FROM A   
115 KT CATEGORY 4 HURRICANE TO A TROPICAL STORM IN JUST 24 HOURS...
THIS IS AN EXAMPLE OF EXTREME RAPID FILLING FOR A CYCLONE OVER
WATER.  AS THE SYSTEM CONTINUES MOVING OVER COLDER WATERS AND INTO
STRONG SHEAR...ADRIAN SHOULD CONTINUE TO WEAKEN UNTIL DISSIPATION
IN ABOUT TWO TO THREE DAYS.  THE INTENSITY FORECAST IS SIMILAR TO
THE LGEM STATISTICAL MODEL AND IS SLIGHTLY LOWER THAN THAT
INDICATED IN THE PREVIOUS ADVISORY.

ADRIAN IS MOVING WESTWARD AT ABOUT 10 KT PRIMARILY UNDER THE
INFLUENCE OF A MID-LEVEL RIDGE TO ITS NORTH.  A VIGOROUS SHORT-WAVE
TROUGH CURRENTLY DIGGING SOUTHEASTWARD OFF OF CALIFORNIA MAY ACT TO
TURN THE CYCLONE WEST-NORTHWESTWARD DURING THE NEXT DAY OR SO. 
HOWEVER...ONCE THE THE DEEP CONVECTION IS GONE FROM THIS SYSTEM IN
ABOUT 36-48 HOURS THE CYCLONE SHOULD BE STEERED BY THE LOW-LEVEL
FLOW.  THE TRACK FORECAST IS SIMILAR TO THE CONSENSUS OF THE
DYNAMICAL MODELS THROUGH 36 HOURS AND THEN TO BAM-SHALLOW
THEREAFTER.  NO SIGNIFICANT CHANGES TO THE TRACK PREDICTION WERE
MADE FROM THE PREVIOUS ADVISORY.
 
FORECAST POSITIONS AND MAX WINDS
 
INIT  11/1500Z 15.8N 111.5W   60 KT  70 MPH
 12H  12/0000Z 16.0N 112.8W   45 KT  50 MPH
 24H  12/1200Z 16.5N 113.9W   35 KT  40 MPH
 36H  13/0000Z 17.1N 115.0W   30 KT  35 MPH
 48H  13/1200Z 18.0N 115.8W   25 KT  30 MPH...POST-TROP/REMNT LOW
 72H  14/1200Z 20.0N 117.0W   25 KT  30 MPH...POST-TROP/REMNT LOW
 96H  15/1200Z...DISSIPATED
 
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FORECASTER LANDSEA/AVILA
 
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