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Hurricane Olivia Discussion Number  28
NWS National Hurricane Center Miami FL       EP172018
800 AM PDT Fri Sep 07 2018

Although Olivia is still a major hurricane, the cloud tops have
warmed some over the past several hours and the eye is not quite as
distinct as it was overnight.  All of the satellite intensity
estimates have decreased this cycle, and the initial intensity is
lowered to 100 kt using that data.  Satellite data indicate that
Olivia is an annular hurricane with a well organized inner core, but
with a lack of outer banding features.

The hurricane is moving west-northwestward at 14 kt.  The track
forecast philosophy appears fairly straightforward.  Olivia is
expected to move westward to west-northwestward during the next few
days as it remains steered by a subtropical ridge to its north.  By
the end of the forecast period, a turn to the west-southwest is
expected as ridging builds to the northwest of the cyclone.
The NHC track forecast remains near the middle of the guidance
envelope, in best agreement with the consensus aids.  Based on
this forecast, Olivia is expected to cross into the central Pacific
basin by late Saturday.

Olivia is over cool 25-26 deg C waters, and it will remain over
these waters during the next several days.  These marginal SSTs
combined with drier air should cause a slow weakening trend through
the forecast period.  However, as mentioned in previous discussions,
research has proven that annular hurricanes like Olivia weaken
slower than normal in these types of conditions.  Therefore, the
NHC intensity forecast shows a slower rate of weakening than the
IVCN and HCCA models.

FORECAST POSITIONS AND MAX WINDS

INIT  07/1500Z 20.1N 132.5W  100 KT 115 MPH
 12H  08/0000Z 20.7N 134.5W   90 KT 105 MPH
 24H  08/1200Z 21.3N 137.0W   80 KT  90 MPH
 36H  09/0000Z 21.7N 139.7W   75 KT  85 MPH
 48H  09/1200Z 22.0N 142.3W   70 KT  80 MPH
 72H  10/1200Z 22.3N 146.9W   65 KT  75 MPH
 96H  11/1200Z 22.0N 150.5W   60 KT  70 MPH
120H  12/1200Z 21.0N 155.0W   55 KT  65 MPH

$$
Forecaster Cangialosi

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