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Hurricane SEYMOUR Forecast Discussion

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WTPZ45 KNHC 252037

200 PM PDT TUE OCT 25 2016

Seymour has continued to intensify since the last advisory, with
the 15 n mi wide eye continuing to become better defined inside the
central dense overcast.  Satellite intensity estimates from TAFB,
SAB, and the CIMSS satellite consensus are all 115 kt, so that is
the initial intensity for this advisory.  The hurricane currently
has good cirrus outflow in all directions except to the south.

Seymour is expected to remain within an area of low wind shear and
over SSTs of around 28C for the next 12-18 hours, and thus some
additional strengthening is possible.  After 18 hours, increasing
southwesterly shear and cooler waters should cause steady to rapid
weakening.  The majority of the guidance continues to show Seymour
weakening below hurricane strength in less than 72 hours,
degenerating to a remnant low by 96 hours, and dissipating
completely by 120 hours.  The new intensity forecast is an update
of the previous forecast and again lies near the upper end of the
intensity guidance.

The initial motion is still 275/12.  A mid- to upper-level ridge
extending westward from Mexico is expected to steer Seymour westward
to west-northwestward for another 12-24 hours.  Subsequently, a
deep-layer trough over the northeastern Pacific is expected to cause
a break in the ridge, with Seymour turning northwestward and
northward into the break.  Most of the track guidance suggests the
forward motion should slow after 48 hours as Seymour shears apart,
and it now suggests that the hurricane should turn more westward
before dissipation as it is steered by low-level easterly flow.  The
new forecast track is similar to the previous track for the first 72
hours, then it is shifted a little westward at the 96 hour point.


INIT  25/2100Z 15.7N 116.4W  115 KT 130 MPH
 12H  26/0600Z 16.2N 118.2W  120 KT 140 MPH
 24H  26/1800Z 17.2N 120.3W  110 KT 125 MPH
 36H  27/0600Z 18.5N 121.7W   95 KT 110 MPH
 48H  27/1800Z 19.9N 122.4W   80 KT  90 MPH
 72H  28/1800Z 21.0N 122.5W   40 KT  45 MPH
 96H  29/1800Z 21.5N 123.5W   20 KT  25 MPH...POST-TROP/REMNT LOW
120H  30/1800Z...DISSIPATED

Forecaster Beven