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Hurricane ALETTA


Hurricane Aletta Discussion Number  11
NWS National Hurricane Center Miami FL       EP022018
300 AM MDT Fri Jun 08 2018

Aletta's impressive satellite presentation has not changed much
since the 6Z special advisory.  Thus the initial wind speed will
stay 105 kt, which is very similar to a blend of the latest Dvorak
estimates.  The hurricane has less than a day to strengthen before
the environment becomes less hospitable, with a notable increase in
shear and decrease in water temperatures forecast this weekend.
These conditions will likely cause significant weakening of Aletta
over the weekend, with rapid weakening predicted by Sunday.  The
official forecast is similar to the previous one, but has been
lowered at long range in accordance with the latest guidance.  The
GFS and ECMWF suggest Aletta will lose deep convection by day 4, so
the remnant low timing has been moved up to that day.

The hurricane has been moving slowly at about 5 kt during the
night, with a motion toward the west-northwest or northwest.  As the
shear increases on Saturday, Aletta should turn a little more to
the northwest as the deep circulation feels the southwesterly flow
associated with a broad upper trough over the eastern Pacific.  By
Monday, the cyclone should turn more to the west-northwest and then
westward by the end of the forecast due to Aletta becoming a more
shallow system and being steered by a low-level ridge.  One notable
outlier is the ECMWF model, which moves Aletta more westward almost
immediately, resulting in a much farther south track than the other
models.  This model has had a southward bias for this storm and is
weighted less it normally would be in this advisory package.  The
new forecast is close to the previous one, which also put less
weight on the ECMWF solution, and lies near the evenly weighted
track consensus TVCE.


INIT  08/0900Z 15.8N 110.7W  105 KT 120 MPH
 12H  08/1800Z 16.1N 111.5W  115 KT 130 MPH
 24H  09/0600Z 16.7N 112.4W  105 KT 120 MPH
 36H  09/1800Z 17.4N 113.2W   85 KT 100 MPH
 48H  10/0600Z 18.2N 114.0W   70 KT  80 MPH
 72H  11/0600Z 19.3N 116.0W   40 KT  45 MPH
 96H  12/0600Z 20.0N 118.0W   25 KT  30 MPH...POST-TROP/REMNT LOW
120H  13/0600Z 20.5N 119.5W   20 KT  25 MPH...POST-TROP/REMNT LOW

Forecaster Blake