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Hurricane Fernanda Discussion Number   9
NWS National Hurricane Center Miami FL       EP062017
800 PM PDT Thu Jul 13 2017

Fernanda continues to strengthen. Although there has been no hint
of an eye in geostationary satellite imagery, the center is
embedded within a symmetric CDO and a recent SSMIS overpass
revealed a small banded eye.  The upper-level outflow is well
established over the eastern and southern semicircles but there is
some evidence of a little northerly shear beneath the high cirrus
layer that may have temporarily slowed the intensification process.
Subjective and objective Dvorak T-numbers range from T4.0 to
T4.6, which yields an initial intensity estimate of 75 kt.

The upper-level pattern over the cyclone is forecast to become
ideal for strengthening with the shear remaining quite low
throughout the forecast period.  As a result, significant
strengthening is forecast while the hurricane moves over SSTs of
28-29 deg C during the next couple of days.  The SHIPS Rapid
Intensification Index is still indicating a notable chance of RI
over the next 24 hours, and the NHC foreast once again calls for
rapid strengthening during the next 24 to 36 hours. After that time,
eyewall replacement cycles could cause some fluctuations in
intensity. In about 72 hours, the hurricane is expected to begin
moving over cooler water which should result in weakening late in
the period.

Recent satellite fixes show that Fernanda is moving slightly south
of west or 260/10 kt.  A deep-layer ridge to the north of the
cyclone is expected to keep the hurricane on a general westward
heading during the next day or so.  After that time, a mid- to
upper-level trough to the northeast of the Hawaiian Islands is
expected to cause the western portion of the ridge to weaken.
This should cause Fernanda to turn west-northwestward over the
weekend. The track guidance is in very good agreement, and the
new NHC track is essentially an update of the previous advisory.


FORECAST POSITIONS AND MAX WINDS

INIT  14/0300Z 11.0N 117.0W   75 KT  85 MPH
 12H  14/1200Z 10.9N 118.3W   90 KT 105 MPH
 24H  15/0000Z 10.8N 120.2W  105 KT 120 MPH
 36H  15/1200Z 11.1N 122.3W  115 KT 130 MPH
 48H  16/0000Z 11.7N 124.6W  120 KT 140 MPH
 72H  17/0000Z 13.0N 129.2W  120 KT 140 MPH
 96H  18/0000Z 14.4N 133.2W  105 KT 120 MPH
120H  19/0000Z 15.8N 137.0W   85 KT 100 MPH

$$
Forecaster Brown

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