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Tropical Storm ALETTA


Tropical Storm Aletta Discussion Number  22
NWS National Hurricane Center Miami FL       EP022018
800 PM PDT Sun Jun 10 2018

Aletta is maintaining its sheared structure.  Although cloud tops
have warmed over the past few hours, the tropical storm is still
producing persistent convection in the northwestern quadrant. Dvorak
classifications from TAFB and SAB have not changed since 6 hours
ago, so the intensity has been held at 40 kt.  No change has been
made to the intensity forecast.  Aletta has been moving along a
tongue of moderately warm water, which may have allowed convection
to persist up to this point, but the cyclone will soon cross a sharp
SST gradient and enter into a much more stable environment.  Once
that occurs, the cyclone will likely lose all convection and become
a remnant low, gradually spinning down over the course of a few
days.  While not explicitly shown in this forecast, it is possible
that Aletta will dissipate by the middle to end of the week.

The tropical storm has been moving toward the west-northwest, or
285/6 kt, this evening, but a westward motion is expected to resume
overnight.  All of the dynamical models continue to indicate that
Aletta will be steered slowly westward by a mid-level ridge to the
north for the next 24 to 36 hours.  After that time, a turn toward
the west-southwest will likely occur as the low-level tradewinds
become the dominant steering feature.  From day 3 onward, the
cyclone is expected to become trapped in light low-level flow
between a high pressure system to the northwest and Hurricane Bud to
the east, so the NHC forecast shows little to no movement.  The
official track forecast has been adjusted slightly northward for the
first 36 hours due to Aletta's recent short-term west-northwestward
motion, but is not significantly changed from the previous advisory
and remains close to TVCN and HCCA.


INIT  11/0300Z 16.8N 116.2W   40 KT  45 MPH
 12H  11/1200Z 16.9N 117.2W   35 KT  40 MPH
 24H  12/0000Z 16.9N 118.3W   30 KT  35 MPH
 36H  12/1200Z 16.7N 119.4W   25 KT  30 MPH...POST-TROP/REMNT LOW
 48H  13/0000Z 16.4N 119.9W   25 KT  30 MPH...POST-TROP/REMNT LOW
 72H  14/0000Z 16.2N 120.2W   20 KT  25 MPH...POST-TROP/REMNT LOW
 96H  15/0000Z 16.0N 120.5W   20 KT  25 MPH...POST-TROP/REMNT LOW
120H  16/0000Z 16.0N 120.5W   15 KT  15 MPH...POST-TROP/REMNT LOW

Forecaster Zelinsky