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Hurricane John Discussion Number   8
NWS National Hurricane Center Miami FL       EP122018
900 AM MDT Tue Aug 07 2018

Visible and infrared satellite images have continued to show the
ragged eye of John this morning, but the surrounding convective
cloud tops have become more symmetric and cooled since the previous
advisory.  The latest Dvorak satellite intensity estimates from
TAFB and SAB were T5.0/90 kt, which support increasing the initial
wind speed to that value.  John has about another 24 hours over
warm water in which to intensify, and the NHC intensity forecast
calls for John to attain major hurricane strength later today or
tonight.  After that time, decreasing SSTs and a more stable
environment should lead to steady or rapid weakening, and John is
expected to become a post-tropical cyclone by day 4.  The NHC
intensity forecast is near the SHIPS and HCCA models for the first
12 to 24 hours, and then is between the aforementioned models and
the intensity consensus thereafter.

John is moving northwestward or 320/8 kt.  The track guidance is in
good agreement on taking the hurricane northwestward around the
western portion of a mid-level ridge centered over northern Mexico.
Once John weakens and becomes a vertically shallow system it should
turn westward in the low-level flow.  The NHC track forecast is
near the middle of the tightly clustered guidance envelope.

The dangerous core of John is forecast to remain well offshore of
the Baja California Peninsula.  However, an eastward shift of the
forecast track or an unexpected increase in the size of the outer
wind field of the hurricane could bring tropical-storm-force winds
to portions of the west coast of the peninsula. Therefore, interests
in the southern portion of the Baja California Peninsula should
monitor the progress of this hurricane.

FORECAST POSITIONS AND MAX WINDS

INIT  07/1500Z 17.9N 109.8W   90 KT 105 MPH
 12H  08/0000Z 18.9N 110.7W  100 KT 115 MPH
 24H  08/1200Z 20.5N 112.2W  105 KT 120 MPH
 36H  09/0000Z 22.0N 114.0W   90 KT 105 MPH
 48H  09/1200Z 23.5N 116.1W   80 KT  90 MPH
 72H  10/1200Z 26.2N 120.2W   50 KT  60 MPH
 96H  11/1200Z 27.0N 123.8W   40 KT  45 MPH...POST-TROPICAL
120H  12/1200Z 27.0N 126.8W   30 KT  35 MPH...POST-TROP/REMNT LOW

$$
Forecaster Brown

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