000
WTPZ43 KNHC 080233
TCDEP3

HURRICANE BLAS DISCUSSION NUMBER  21
NWS NATIONAL HURRICANE CENTER MIAMI FL       EP032016
800 PM PDT THU JUL 07 2016

The eye feature has become less discernible in enhanced
infrared imagery this evening, and the inner core cloud top
temperatures have warmed considerably.  A compromise of all
available subjective and objective Dvorak intensity estimates
yields an initial intensity of 95 kt.  Blas is expected to
accelerate its spin down as the cyclone continues to traverse a
rather sharp sea surface temperature gradient and reaches sub-24C
waters by the 36 hour period.  Blas is forecast to weaken to
a tropical storm by that time, and ultimately become a remnant low
in 3 days, or earlier.  The official forecast intensity is
basically an update of the previous advisory and is close to the
Florida State Superensemble.

The initial motion is west-northwestward or 295/8, within the
southwestern peripheral steering flow of a mid-level ridge
originating over eastern Mexico.  Large-scale models all show the
cyclone gradually turning northwestward in 12 hours as Blas
enters a growing weakness produced by a large cut-off low northeast
of the Hawaiian Islands.  As the weakening trend accelerates and
Blas becomes a vertically shallower system, the post-tropical
remnant low is expected to turn westward in the easterly flow of the
trades.  The NHC forecast is based on a blend of the previous
forecast and a consensus of the ECMWF and GFS (GFEX).

FORECAST POSITIONS AND MAX WINDS

INIT  08/0300Z 16.9N 128.6W   95 KT 110 MPH
 12H  08/1200Z 17.6N 129.7W   85 KT 100 MPH
 24H  09/0000Z 18.8N 131.0W   65 KT  75 MPH
 36H  09/1200Z 20.2N 132.4W   55 KT  65 MPH
 48H  10/0000Z 21.5N 133.9W   40 KT  45 MPH
 72H  11/0000Z 22.5N 137.7W   30 KT  35 MPH...POST-TROP/REMNT LOW
 96H  12/0000Z 22.3N 142.3W   25 KT  30 MPH...POST-TROP/REMNT LOW
120H  13/0000Z 21.7N 146.9W   20 KT  25 MPH...POST-TROP/REMNT LOW

$$
Forecaster Roberts