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Hurricane Rosa Discussion Number   7
NWS National Hurricane Center Miami FL       EP202018
300 PM MDT Wed Sep 26 2018

Rosa continues to strengthen this afternoon. Improved deep
convective banding features with -83C cloud tops are evident in both
visible and microwave images, particularly in the east semicircle.
The initial intensity is bumped up to 70 kt and is a compromise of
the subjective and objective satellite intensity estimates.

It still appears likely that Rosa will continue to quickly
strengthen through this evening while it moves over warm oceanic
temperatures and in a high moisture and low shear atmospheric
environment.  The official forecast is based on a blend of the IVCN
and NOAA-HCCA intensity consensus models, and shows strengthening,
at a slower pace, after the RI period.  Beyond 48 hours, steady
weakening is forecast due to decreasing sea surface temperatures,
increasing southwesterly shear, and a high statically stable
surrounding environment.

Rosa is currently moving west-northwestward, or 285/9 kt, within the
mid-level easterly steering flow produced by a mid-level ridge
extending from northern Mexico westward over the eastern Pacific.
At around day 3, Rosa is expect to move northwestward and then
northward day 4 in response to a mid-latitude trough approaching
from the northwest.  The along track spread beyond day 3 continues
to be an issue with the GFS global and HWRF hurricane model
indicating a much more faster north to north-northeast motion
than the slower European model cluster.  In this scenario,
the NHC forecast will remain near the better performing various
multi-model consensus models.

FORECAST POSITIONS AND MAX WINDS

INIT  26/2100Z 16.5N 112.2W   70 KT  80 MPH
 12H  27/0600Z 16.7N 113.6W   90 KT 105 MPH
 24H  27/1800Z 16.9N 115.3W  100 KT 115 MPH
 36H  28/0600Z 17.2N 116.7W  105 KT 120 MPH
 48H  28/1800Z 17.8N 117.7W  110 KT 125 MPH
 72H  29/1800Z 20.1N 119.4W   95 KT 110 MPH
 96H  30/1800Z 23.3N 119.2W   80 KT  90 MPH
120H  01/1800Z 26.6N 117.5W   60 KT  70 MPH

$$
Forecaster Roberts

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