000
WTPZ43 KNHC 030858
TCDEP3

TROPICAL STORM BLAS DISCUSSION NUMBER   2
NWS NATIONAL HURRICANE CENTER MIAMI FL       EP032016
300 AM MDT SUN JUL 03 2016

Conventional and microwave satellite imagery indicate that a long
curved band of convection now wraps at least half way around the
low-level center. Dvorak satellite intensity estimates have
increased as result, with TAFB coming in at T2.5/35 kt and SAB at
T3.0/45 kt. Therefore, the depression has been upgraded to Tropical
Storm Blas.

The initial motion estimate is 285/12, based heavily on microwave
fix positions. Overall, there is no significant change to the
previous forecast track or reasoning. Blas is expected to move
along the southwestern periphery of a deep-layer subtropical ridge
located over northern Mexico and the southern United States.  This
stable steering pattern should keep Blas moving in a general
westward to west-northwestward direction for the next 120 hours.
The NHC track forecast is slightly north of the previous forecast
track, and closely follows the consensus track model TVCE.

Environmental conditions appear favorable for steady strengthening
during the next 72 hours as Blas moves over SSTs of 29-30C and
encounters decreasing vertical wind shear of less than 10 kt. The
new NHC intensity forecast shows Blas becoming a hurricane on Monday
and a major hurricane by Wednesday. Gradual weakening is expected to
begin by 96 hours or so as the cyclone starts to move over 26C or
cooler seas-surface temperatures, which should result in some cold
upwelling or mixing beneath Blas. The official forecast is above the
intensity consensus IVCN, and close to the previous intensity
forecast and a blend of the SHIPS and LGEM models.

FORECAST POSITIONS AND MAX WINDS

INIT  03/0900Z 11.7N 109.7W   35 KT  40 MPH
 12H  03/1800Z 12.0N 111.0W   45 KT  50 MPH
 24H  04/0600Z 12.6N 113.1W   55 KT  65 MPH
 36H  04/1800Z 13.1N 115.3W   65 KT  75 MPH
 48H  05/0600Z 13.6N 117.5W   80 KT  90 MPH
 72H  06/0600Z 14.6N 122.1W  100 KT 115 MPH
 96H  07/0600Z 15.8N 126.4W   95 KT 110 MPH
120H  08/0600Z 17.3N 130.1W   80 KT  90 MPH

$$
Forecaster Stewart