000
WTPZ43 KNHC 042039
TCDEP3

HURRICANE BLAS DISCUSSION NUMBER   8
NWS NATIONAL HURRICANE CENTER MIAMI FL       EP032016
200 PM PDT MON JUL 04 2016

Blas' cloud pattern has not changed much in organization since this
morning, except for the emergence of what appears to be a ragged,
banding-type eye.  The cyclone's central features are still not that
well organized, although there are some recent signs that this may
be changing.  A dry slot of air has also been wrapping around the
western half of the circulation.  Dvorak classifications remain T4.0
and T4.5 from SAB and TAFB, respectively. A 1652 UTC ASCAT overpass
indicates that Blas is a minimal hurricane at best, and the initial
intensity estimate is held at 65 kt for this advisory.

The latest fixes indicate that the initial motion is a little faster
and has a bit more of a northerly component than yesterday.  The
best estimate is that the cyclone is moving 290/12.  Overall, the
forecast reasoning is unchanged.  Blas should be steered on a west-
northwestward course during the next several days to the south of
a strong, deep-layer subtropical ridge extending westward from
northern Mexico.  A more northwesterly track is possible toward the
end of the forecast period as the cyclone nears the western end of
this ridge.  The new NHC track forecast is adjusted a little to the
north in the short term and lies on the northern side of the
guidance envelope.  The forecast does not deviate much from the
previous forecast beyond day 2 and lies near the multi-model
consensus.

It is unclear as to why Blas has not strengthened much, especially
since the large-scale environment appears conducive for
intensification. The current interruption to the cyclone's
strengthening could be related to a dry air intrusion from an
unknown source and/or some northeasterly shear.  Whatever the cause,
additional strengthening is still indicated, and the new intensity
forecast remains near the upper-end statistical guidance. On days
3-4, Blas will reach the 26-deg sea surface temperature isotherm and
encounter substantially drier and more stable air. This should
result in gradual weakening in an otherwise low-shear environment.
By 96 hours, rapid weakening is expected to commence due to
increasingly unfavorable environmental factors.

The wind radii have been significantly adjusted based on the
aforementioned ASCAT overpass.

FORECAST POSITIONS AND MAX WINDS

INIT  04/2100Z 13.7N 115.7W   65 KT  75 MPH
 12H  05/0600Z 14.1N 117.5W   75 KT  85 MPH
 24H  05/1800Z 14.6N 120.0W   95 KT 110 MPH
 36H  06/0600Z 15.1N 122.5W  105 KT 120 MPH
 48H  06/1800Z 15.6N 124.6W  100 KT 115 MPH
 72H  07/1800Z 16.8N 128.6W   80 KT  90 MPH
 96H  08/1800Z 18.2N 131.7W   60 KT  70 MPH
120H  09/1800Z 20.0N 135.1W   35 KT  40 MPH...POST-TROPICAL

$$
Forecaster Kimberlain