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Hurricane Olivia Discussion Number  15
NWS National Hurricane Center Miami FL       EP172018
800 AM PDT Tue Sep 04 2018

Olivia has become better organized since the last advisory, with
conventional satellite imagery indicating the formation of a 25 n
mi wide eye and a surrounding cold ring of cloud tops in the
eyewall.  Satellite intensity estimates from TAFB and SAB have
increased to 90 kt, and that will be the initial intensity for this
advisory.  This burst of rapid intensification has occurred even
though the analyzed easterly shear in the SHIPS model and analyses
from CIMSS is in the 15-20 kt range.

How much additional intensification will occur is uncertain.  The
intensity guidance suggests that continued shear and decreasing sea
surface temperatures along the forecast track will allow only about
12 h of additional strengthening, and most of the guidance forecasts
only modest strengthening during this time.  However, it is unlikely
that the current rapid intensification will stop that quickly.
Based on this, the new intensity forecast calls for a peak intensity
of 100 kt in 12 h at the upper edge of the intensity guidance, and
it is possible Olivia could get stronger.  After 24 h, the cooler
sea surface temperatures and entrainment of dry air should cause a
gradual weakening even though the shear is forecast to decrease.

The initial motion remains 275/10.  As noted previously, a
building subtropical ridge over the eastern Pacific is forecast
to induce a westward and west-northwestward motion with increasing
forward speed during the next several days.  The model guidance
supports this scenario with a tight clustering, and the new NHC
track forecast is again an update of the previous forecast.


FORECAST POSITIONS AND MAX WINDS

INIT  04/1500Z 17.0N 118.2W   90 KT 105 MPH
 12H  05/0000Z 17.2N 119.9W  100 KT 115 MPH
 24H  05/1200Z 17.4N 122.1W  100 KT 115 MPH
 36H  06/0000Z 18.0N 124.5W   95 KT 110 MPH
 48H  06/1200Z 18.8N 127.2W   85 KT 100 MPH
 72H  07/1200Z 20.5N 133.0W   75 KT  85 MPH
 96H  08/1200Z 22.0N 138.5W   60 KT  70 MPH
120H  09/1200Z 23.0N 143.5W   50 KT  60 MPH

$$
Forecaster Beven

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