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HURRICANE SEYMOUR DISCUSSION NUMBER  13
NWS NATIONAL HURRICANE CENTER MIAMI FL       EP202016
200 AM PDT WED OCT 26 2016

Seymour remains an impressive hurricane in geostationary satellite
pictures, with a very distinct eye surrounded by a symmetric CDO.
Subjective and objective Dvorak current intensity numbers are
unchanged from before and the initial intensity remains 130 kt
for this advisory.  Some slight strengthening is still possible
this morning while Seymour remains over warm water and in a low
shear environment, however, by this afternoon the hurricane will
begin moving over slightly lower SSTs, which should start the
weakening process.  Seymour is forecast to cross the 26 degree
Celsius isotherm tonight and move over colder waters and into an
area of strong southwesterly wind shear thereafter. These conditions
are expected to cause a very rapid decrease in intensity on
Thursday, and Seymour is forecast to become a tropical storm within
48 hours and degenerate into a post-tropical remnant low on Friday
or early Saturday.

The initial motion estimate is 290/12 kt.  A deepening mid- to
upper-level trough seen in water vapor imagery near 140W is expected
to erode the western portion of the ridge that has been steering
Seymour westward during the past few days.  As the ridge weakens,
Seymour is forecast to turn northwestward, then northward ahead of
the trough.  After 48 hours, Seymour's forward motion should
decrease as it becomes vertically shallow and is steered by the
weaker low-level flow.  The latest guidance envelope has shifted
northward and eastward at 36 h and beyond, and the NHC track
forecast has been adjusted accordingly.


FORECAST POSITIONS AND MAX WINDS

INIT  26/0900Z 16.4N 119.0W  130 KT 150 MPH
 12H  26/1800Z 17.2N 120.5W  120 KT 140 MPH
 24H  27/0600Z 18.6N 121.9W   95 KT 110 MPH
 36H  27/1800Z 20.1N 122.5W   75 KT  85 MPH
 48H  28/0600Z 21.2N 122.5W   50 KT  60 MPH
 72H  29/0600Z 22.0N 122.5W   30 KT  35 MPH...POST-TROP/REMNT LOW
 96H  30/0600Z 22.5N 122.5W   20 KT  25 MPH...POST-TROP/REMNT LOW
120H  31/0600Z...DISSIPATED

$$
Forecaster Brown

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