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 584 
 WTPZ42 KNHC 090236
 TCDEP2
 
 Hurricane Aletta Discussion Number  14
 NWS National Hurricane Center Miami FL       EP022018
 900 PM MDT Fri Jun 08 2018
 
 Aletta's weakening phase has begun, with the eye becoming cloud
 filled in visible satellite imagery since the last advisory.
 An analysis from CIMSS at the University of Wisconsin indicates that
 vertical shear has increased to 15-20 kt out of the south-southwest,
 and a 2309 UTC SSMI/S pass confirms that the hurricane's structure
 is responding to that shear.  All final-T numbers have decreased,
 and the initial intensity is set at 110 kt as a blend of the various
 final-T and CI numbers.  This is also supported by the latest SATCON
 estimate.
 
 Vertical shear is forecast to strengthen during the next 36 hours,
 and Aletta will be moving over marginally warm sea surface
 temperatures, both of which should cause the cyclone to continue
 weakening.  The new intensity models are now showing a much more
 significant rate of weakening, and the updated NHC intensity
 forecast follows suit, bringing down the winds much faster than
 shown in the previous forecast.  The NHC forecast is near the top
 end of the guidance for the first 24 hours and then close to the
 ICON intensity consensus from 36 hours and beyond.  Interestingly,
 the HCCA guidance weakens Aletta to a tropical storm within 24
 hours, so it wouldn't be surprising if the hurricane weakens faster
 than shown in the official forecast.  Aletta is now forecast to
 degenerate into a remnant low by day 3.
 
 The initial motion estimate is 285/5 kt.  Since Aletta is moving
 around the southwestern periphery of a mid-level ridge centered over
 northwestern Mexico, the cyclone is expected to maintain a slow
 west-northwestward or northwestward motion for the next 36 hours.
 After that time, the weakening storm should turn back toward the
 west and eventually southwest as it becomes increasingly steered by
 the low-level trade winds and the flow around another developing
 tropical cyclone to the east.  The new NHC track forecast is a
 little south of the previous forecast to account for an overall
 southward shift in the guidance envelope.
 
 FORECAST POSITIONS AND MAX WINDS
 
 INIT  09/0300Z 16.2N 112.3W  110 KT 125 MPH
  12H  09/1200Z 16.6N 113.1W   95 KT 110 MPH
  24H  10/0000Z 17.3N 114.2W   75 KT  85 MPH
  36H  10/1200Z 17.7N 115.2W   55 KT  65 MPH
  48H  11/0000Z 17.8N 116.3W   40 KT  45 MPH
  72H  12/0000Z 17.8N 118.7W   25 KT  30 MPH...POST-TROP/REMNT LOW
  96H  13/0000Z 17.5N 121.0W   25 KT  30 MPH...POST-TROP/REMNT LOW
 120H  14/0000Z 16.5N 122.5W   20 KT  25 MPH...POST-TROP/REMNT LOW
 
 $$
 Forecaster Berg
 
 
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