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Hurricane Sergio Discussion Number  15
NWS National Hurricane Center Miami FL       EP212018
800 PM PDT Tue Oct 02 2018

The eye of Sergio has become obscured over the past several hours,
indicating that the intensifying trend has levelled off.  It
appears that northeasterly shear is affecting the inner core as the
latest microwave data indicate an open eyewall on the northern side
of the hurricane.  The intensity is held at 100 kt for this
advisory since the overall wind speed estimates haven't changed
much, although there is a fair spread in those values.  The shear
is forecast to decrease over the next day or two, which should
allow further strengthening of Sergio, pending any eyewall cycles.
Weakening is expected in the longer range while the hurricane moves
over more shallow marginally warm waters.  Only a small change has
been made to the short term intensity forecast, and the rest of the
forecast is essentially the same.

Sergio has turned toward the west-northwest and slowed down, as
forecast, now 300/9.   A west-northwest or northwest track is
expected as a ridge weakens to the north of Sergio for the next day
or two.  Thereafter, a strong ridge is forecast to build to the
northwest of Sergio, which should force a westward motion.  As has
been the case for many cyclones this season, the GFS-based guidance
is on the right side of track guidance envelope, while the
ECMWF/UKMET are on the left side.  The consensus has remained quite
steady near the previous interpolated official forecast, thus
the new forecast is basically just an update of the previous one.


FORECAST POSITIONS AND MAX WINDS

INIT  03/0300Z 11.8N 115.8W  100 KT 115 MPH
 12H  03/1200Z 12.5N 117.0W  105 KT 120 MPH
 24H  04/0000Z 13.6N 118.5W  115 KT 130 MPH
 36H  04/1200Z 14.6N 119.8W  120 KT 140 MPH
 48H  05/0000Z 15.5N 121.1W  115 KT 130 MPH
 72H  06/0000Z 16.4N 123.6W   95 KT 110 MPH
 96H  07/0000Z 16.5N 126.6W   90 KT 105 MPH
120H  08/0000Z 16.8N 129.5W   85 KT 100 MPH

$$
Forecaster Blake

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