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Hurricane Olivia Discussion Number  20
NWS National Hurricane Center Miami FL       EP172018
200 PM PDT Wed Sep 05 2018

While satellite imagery shows that the erosion of the eyewall
convection is less than seen 6 h ago, the various satellite
intensity estimates indicate that Olivia continues to slowly
weaken.  Based on a blend of these estimates, the initial intensity
is reduced to 85 kt.  Recent satellite data indicate that the wind
and wave fields associated with Olivia are larger than previously
analyzed, and they have been revised for this advisory.

Ongoing moderate easterly shear over Olivia should diminish during
the next 12 h or so.  After that, the major influences on the
intensity should be gradually decreasing sea surface temperatures
along the forecast track and entrainment of air that gets
progressively drier through the forecast period.  The intensity
guidance is still in good agreement that Olivia should weaken
through the forecast period, and the new intensity forecast again
follows this trend.  Overall, the intensity forecast is in best
agreement with the SHIPS model and the IVCN intensity consensus.

The initial motion is now 285/11.  A large deep-layer ridge seen in
water vapor imagery to the north of Olivia should steer the
hurricane generally west-northwestward for the next 2-3 days.
After that time, the ridge builds westward to the northeast and
north of the Hawaiian Islands, and this should cause Olivia to
turn westward.  The track guidance remains in good agreement with
this scenario, although the UKMET and the UKMET ensemble mean are
still showing a motion to the north of the other models.  The new
forecast track is similar to the previous track, and it generally
lies between the track consensus model TVCN and the HFIP corrected
consensus model.


FORECAST POSITIONS AND MAX WINDS

INIT  05/2100Z 17.3N 123.5W   85 KT 100 MPH
 12H  06/0600Z 17.9N 125.3W   80 KT  90 MPH
 24H  06/1800Z 18.6N 127.9W   80 KT  90 MPH
 36H  07/0600Z 19.5N 130.6W   75 KT  85 MPH
 48H  07/1800Z 20.4N 133.3W   70 KT  80 MPH
 72H  08/1800Z 21.5N 138.5W   60 KT  70 MPH
 96H  09/1800Z 22.0N 143.5W   55 KT  65 MPH
120H  10/1800Z 22.5N 148.0W   55 KT  65 MPH

$$
Forecaster Beven

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