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HURRICANE BLAS DISCUSSION NUMBER  14
NWS NATIONAL HURRICANE CENTER MIAMI FL       EP032016
200 AM PDT WED JUL 06 2016

The satellite presentation of Blas has degraded since the previous
advisory, as the convective ring surrounding the eye had warmed and
shrunk.  The eye, however, remains distinct in infrared imagery. The
initial intensity has been lowered to 110 kt, which is a little
above a blend of the latest Dvorak CI and Final-T numbers from TAFB
and SAB.  Sea surface temperatures gradually cool along the forecast
track, which should result in weakening, albeit at a slow pace
during the first day or so.  After 24 hours the rate of weakening
should increase as SSTs fall below 27C.  Blas is expected to become
a post-tropical cyclone in about 4 days and a remnant low by day 5.
The new NHC intensity forecast is close to or a little above the
latest LGEM and IVCN intensity consensus.

The initial motion estimate is 280/10, as Blas has begun to gain
some latitude.  Blas should move west-northwestward for the next 48
hours while being steered around the southwestern periphery of a
mid-level ridge centered over Mexico.  After that time the model
spread increases.  The GFS based guidance, including the HWRF and
GFDL, shows Blas turning northwestward late in the period as it
interacts with an upper-level low northeast of the Hawaiian Islands.
The ECMWF continues to show less interaction between Blas and the
upper-level low and has the cyclone turning westward at days 4-5.
Given the continued spread in the guidance, the NHC track forecast
will stay in the middle of the two extremes and shows a
northwestward to west-northwestward motion at days 4-5.  This
forecast is a little south of the latest GFS/ECMWF consensus.  Given
the uncertainty, there is low confidence in the details of the track
forecast late in the period.

FORECAST POSITIONS AND MAX WINDS

INIT  06/0900Z 14.7N 122.7W  110 KT 125 MPH
 12H  06/1800Z 15.1N 124.2W  105 KT 120 MPH
 24H  07/0600Z 15.7N 126.3W  100 KT 115 MPH
 36H  07/1800Z 16.3N 128.1W   90 KT 105 MPH
 48H  08/0600Z 16.9N 129.7W   75 KT  85 MPH
 72H  09/0600Z 18.8N 132.6W   55 KT  65 MPH
 96H  10/0600Z 21.0N 136.0W   35 KT  40 MPH...POST-TROPICAL
120H  11/0600Z 22.5N 140.0W   25 KT  30 MPH...POST-TROP/REMNT LOW

$$
Forecaster Brennan

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