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HURRICANE IGNACIO DISCUSSION NUMBER   9
NWS NATIONAL HURRICANE CENTER MIAMI FL       EP122015
800 PM PDT WED AUG 26 2015

Ignacio's convective cloud pattern has continued to improve and
recent passive microwave satellite imagery indicates that the
cyclone has developed a large but closed eye, which is embedded in
the center of a smooth CDO feature. Upper-level outflow is
well-defined in all quadrants and is expanding. The initial
intensity of 65 kt is based on an average of satellite intensity
estimates of T4.4/75 kt from UW-CIMSS ADT, T4.0/65 kt from TAFB,
and T3.5/55 kt from SAB. This makes Ignacio the seventh hurricane of
the 2015 eastern North Pacific season.

Microwave satellite fixes indicate that Ignacio has finally made
the expected turn toward the west-northwest, and the motion estimate
is now 290/11 kt. A west-northwestward motion is expected to
continue throughout the forecast period due to a strong subtropical
ridge to the north of Ignacio producing a deep layer of
east-southeasterly steering flow. Although the GFS and ECMWF models
differ widely on the track of the hurricane after 72 hours, the
other reliable guidance models lie between those two aforementioned
extremes. The NHC official forecast track lies close to the
previous advisory track and a blend of the various consensus models.

Environmental conditions are expected to generally be favorable for
additional strengthening throughout the forecast period. The main
hindering factor will be modest vertical wind shear for the next
24-36 hours, after which the shear is expected to decrease to less
than 10 kt. However, given the very impressive outflow pattern that
has developed, along with the aforementioned eye feature, rapid
intensification is a distinct possibility during the next 24
hours. By days 4 and 5, thermodynamic and oceanic conditions are
expected to become less favorable, and gradual weakening is
expected to occur during that time. The official intensity
forecast is similar to the previous advisory, and is close to the
consensus model IVCN.

FORECAST POSITIONS AND MAX WINDS

INIT  27/0300Z 12.2N 137.5W   65 KT  75 MPH
 12H  27/1200Z 12.8N 138.9W   75 KT  85 MPH
 24H  28/0000Z 13.8N 140.9W   85 KT 100 MPH
 36H  28/1200Z 14.6N 142.7W   95 KT 110 MPH
 48H  29/0000Z 15.4N 144.4W  100 KT 115 MPH
 72H  30/0000Z 16.7N 147.4W   95 KT 110 MPH
 96H  31/0000Z 18.1N 150.4W   85 KT 100 MPH
120H  01/0000Z 19.5N 153.5W   75 KT  85 MPH

$$
Forecaster Stewart

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