Tropical Cyclone Discussion
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WTPZ45 KNHC 240853

300 AM MDT MON OCT 24 2016

Seymour continues to strengthen this morning.  Satellite data
indicate that the banding features have continued to improve
and a small central dense overcast feature has developed and
become more symmetric.  Although earlier microwave imagery revealed
a mid-level eye feature, there has been no recent microwave data to
diagnose the structure of the inner core. Subjective and objective
Dvorak intensity estimates have increased to 55 and 65 kt,
respectively, and as a result the initial intensity has been
raised to 55 kt.

Seymour continues to move west-northwestward at about 13 kt.
There has been no change to the track forecast reasoning from
the previous advisory.  Seymour should continue moving
west-northwestward to the south of a deep-layer ridge that
extends westward from Mexico.  In a couple of days, the cyclone
will approach the western portion of the ridge and Seymour should
respond by turning northwestward.  After 72 hours, an approaching
shortwave trough should steer Seymour northward, then northeastward.
The model guidance is in good agreement through the first 3 days,
but after that time there is more spread in the track models this
cycle.  The ECMWF and UKMET models have trended faster and take
Seymour much farther north at 96 h and 120 h than the remainder of
the guidance.  Since Seymour is expected to rapidly weaken and
become an increasingly shallow system, the NHC forecast leans toward
the slower and more southern solutions late in the forecast period.

Seymour is forecast to traverse very warm water and remain within
an environment of low vertical wind shear and high mid-level
moisture during the next day or two.  These conditions should allow
the cyclone to quickly strengthen during the next 24 to 36 hours and
like the previous advisory, the new NHC intensity forecast calls for
rapid strengthening during the next 24 hours.  In fact, the SHIPS
Rapid Intensification Index gives a 78 percent chance of a 30 kt or
more increase in wind speed during the next 24 hours. The updated
NHC intensity forecast now shows a peak intensity of 100 kt in 48
hours, which is slightly below the LGEM, FSSE, and NOAA corrected
consensus (HCCA) models.  After 72 hours, increasing southwesterly
shear and cooler SSTs are expected to cause a rapid spin down of the
tropical cyclone.


INIT  24/0900Z 14.9N 108.5W   55 KT  65 MPH
 12H  24/1800Z 15.4N 110.5W   70 KT  80 MPH
 24H  25/0600Z 16.0N 113.2W   85 KT 100 MPH
 36H  25/1800Z 16.4N 115.6W   95 KT 110 MPH
 48H  26/0600Z 17.0N 117.9W  100 KT 115 MPH
 72H  27/0600Z 19.6N 121.1W   85 KT 100 MPH
 96H  28/0600Z 23.0N 121.3W   55 KT  65 MPH
120H  29/0600Z 24.5N 120.0W   30 KT  35 MPH

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