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HURRICANE BLAS DISCUSSION NUMBER   7
NWS NATIONAL HURRICANE CENTER MIAMI FL       EP032016
900 AM MDT MON JUL 04 2016

Blas' cloud pattern consists of a large mass of cold-topped central
convection and a couple of fragmented outer bands.  A 1027 UTC SSM/I
pass revealed a ragged mid-level eye feature, but the low-level
structure appeared less organized.  Dvorak satellite classifications
were T4.0/65 kt and T4.5/77 kt from SAB and TAFB, respectively.
Taking into account the overnight ASCAT pass, the initial intensity
is set at 65 kt, the low end of the intensity estimates.

The initial motion estimate is unchanged at 285/11.  The track
forecast remains straightforward. Blas is expected to be steered
along the southern side of a deep-layer subtropical ridge extending
westward from northern Mexico and the southern United States during
the next 3-4 days.  The cyclone should reach the western periphery
of the ridge by days 4-5, which should result in a turn nearly
toward the northwest.  The model guidance is in relatively good
agreement throughout the forecast period, though the GFS and ECMWF
models diverge some after day 3.  The NHC track forecast does not
deviate much from the previous one and is north of the southernmost
ECMWF owing to the forecast of a strong hurricane, more like the GFS
solution indicates.

The large-scale environment surrounding Blas is characterized by
light to moderate northeasterly shear and a rich supply of
moisture.  Coupled with warm-enough waters, Blas should intensify
into a large and intense hurricane during the next couple of days
once it establishes a better organized inner core. The NHC intensity
forecast continues to lean heavily on the statistical guidance, some
of which strengthens Blas even more than the current forecast.
Around 72 hours, even though the shear should still be low, the
hurricane should enter a drier and more stable environment and begin
traversing sub-26 deg C waters.  This should promote a slow
weakening trend that will accelerate after 96 hours once Blas moves
over much cooler waters.



FORECAST POSITIONS AND MAX WINDS

INIT  04/1500Z 13.3N 114.4W   65 KT  75 MPH
 12H  05/0000Z 13.6N 116.2W   75 KT  85 MPH
 24H  05/1200Z 14.1N 118.7W   90 KT 105 MPH
 36H  06/0000Z 14.6N 121.2W  105 KT 120 MPH
 48H  06/1200Z 15.1N 123.5W  110 KT 125 MPH
 72H  07/1200Z 16.3N 127.6W   95 KT 110 MPH
 96H  08/1200Z 17.8N 131.3W   75 KT  85 MPH
120H  09/1200Z 19.8N 134.7W   50 KT  60 MPH

$$
Forecaster Kimberlain

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