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HURRICANE BLAS DISCUSSION NUMBER  15
NWS NATIONAL HURRICANE CENTER MIAMI FL       EP032016
800 AM PDT WED JUL 06 2016

The overall satellite appearance of Blas has changed little since
early this morning.  Blas has characteristics of an annular
hurricane with a large 25 to 30 n mi wide eye surrounded by a
symmetric convective ring with little outer banding features.  The
initial intensity remains 110 kt, and is a blend of the various
objective and subjective Dvorak satellite intensity estimates.
Blas is currently in a low shear environment and over SSTs of 27-28
degrees Celsius.  Although the shear is forecast to remain low for
the next several days, decreasing sea surface temperatures along the
forecast track should result in gradual weakening of the hurricane
during the next 24 to 36 hours.  After that time, Blas will be
moving over SSTs below 26C which should cause a faster rate of
weakening, and the cyclone is forecast to become post-tropical in
about 4 days.  The NHC intensity forecast is similar to the previous
advisory and lies between the SHIPS and LGEM models.

Blas is moving west-northwestward or 285 degrees at 10 kt, and
should continue on this general motion during the next 36 to 48
hours while it moves around the southwestern portion of a mid-level
ridge over northern Mexico.  By 72 hours, the model guidance begins
to diverge with the GFS, HWRF, GFDL, and GFS ensemble mean taking
Blas northwestward around the eastern portion of a large mid- to
upper-level low to the northeast of Hawaii.  The ECMWF and UKMET
models show a more westward track, with less interaction between the
upper-low and the hurricane.  This appears to be the result of the
size, location, and orientation of the upper-low in the various
models. Given the large spread in the guidance, there is low
confidence in the the track forecast late in the period, and the NHC
forecast track remains near the GFS/ECMWF consensus at days 3-5.


FORECAST POSITIONS AND MAX WINDS

INIT  06/1500Z 15.0N 123.6W  110 KT 125 MPH
 12H  07/0000Z 15.4N 125.2W  105 KT 120 MPH
 24H  07/1200Z 16.0N 127.1W   95 KT 110 MPH
 36H  08/0000Z 16.6N 128.8W   85 KT 100 MPH
 48H  08/1200Z 17.5N 130.4W   70 KT  80 MPH
 72H  09/1200Z 19.6N 133.3W   50 KT  60 MPH
 96H  10/1200Z 21.8N 137.0W   35 KT  40 MPH...POST-TROPICAL
120H  11/1200Z 22.5N 140.5W   25 KT  30 MPH...POST-TROP/REMNT LOW

$$
Forecaster Brown

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