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Eastern North Pacific Tropical Weather Discussion

AXPZ20 KNHC 232149

Tropical Weather Discussion
NWS National Hurricane Center Miami FL
2205 UTC Sun Oct 23 2016

Tropical Weather Discussion for the eastern Pacific Ocean from
the Equator to 32N, east of 140W. The following information is
based on satellite imagery, weather observations, radar, and
meteorological analysis.

Based on 1800 UTC surface analysis and satellite imagery through
2100 UTC.


Tropical Depression 20-E strengthens to tropical storm Seymour at
2100 UTC. At this time, Seymour is located near 13.9N 105.9W or
about 320 nm...590 km SSW of Manzanillo Mexico, moving W-NW or
290 deg at 12 KT. Maximum sustained winds are 35 kt with gusts to
45 kt. Minimum central pressure is 1005 mb. Strengthening is expected 
during the next 48 hours, and Seymour is forecast to become a
hurricane by Tuesday. Currently, numerous moderate to isolated
strong convection is noted within 120 nm W semicircle. Scattered
moderate isolated strong is elsewhere from 12N to 17N between 102W
AND 108W. Although the forecast track keeps Seymour outside of the
forecast zones, fresh to strong winds are expected to affect the
southern part of zones PMZ023 and PMZ025 tonight through late
Monday when the tropical cyclone turns more westward. For
additional details, refer to the latest NHC forecast/advisory
under AWIPS/WMO headers MIATCMEP5/WTPZ25.


The monsoon trough extends across the Gulf of Panama near 08N79W
to 09N96W, then resumes W of T.S. Seymour at 15N100W to 1009 mb
low pres near 16N115W to 1009 mb low pres near 13N127W to 11N135W
to beyond 12N140W. Scattered moderate isolated strong convection
from 12N to 15N between 112W and 118W.



See special features for T.S. Seymour. A 1016 mb surface high is
analyzed at 25N113W surrounded by light anticyclonic winds across
the waters W of the Baja Peninsula. Combined seas are in the 3 to
6 ft range, except 7 to 8 ft N of 27N W of 117W due to long
period NW swell that will subside below 8 ft tonight. The high
will dissipate in about 24 hours while another high pres center of
1016 mb will remain nearly stationary near 25N125W. 

Strong to near gale force winds are expected to surge across the
Tehuantepec area over the next several days. Winds may reach
minimal gale force during the overnight and early morning hours
with the assistance of the nocturnal drainage flow.

Inside the Gulf of California, mainly gentle southerly winds are
noted based on scatterometer and surface data. This general wind
direction will persist tonight, then light and variable winds are
expected on Mon.


Gulf of Papagayo: moderate to fresh NE winds are expected across
and just downstream of the Gulf of Papagayo tonight into early Mon

Gentle to moderate S to SW winds are noted S of 06N, while gentle
to moderate W to NW winds are N of 06N, with the exception of
moderate to fresh southerly winds from 05N to 07N E of 80W. These
increasing winds could be associated with some convection
previously noted across this area. Combined seas of 4 to 6 ft,
primarily in long- period SW swell dominate the offshore waters.
These marine conditions will persist over the few days.


See special features concerning TD 20-E. 

A weak ridge dominates most of the north waters N of 20N W of
118W. Under the influence of this system, mainly light and
variable winds are noted per scatterometer data. Winds will
increase to 15-20 kt near the monsoon trough due to the presence
of a couple of weak low pres systems along the trough, and their
associated convection.

Seas to 8 ft in NW swell are noted per altimeter data N of 22N
between 117W and 131W. Seas are forecast to subside to less than 8
ft across this area tonight. 

A cold front will enter the NW waters near 30N140W tonight and
will move across the NW waters on Monday, stretching from
30N133W by Monday evening. This front will be reinforcing by a
second cold front reaching the same area on Tue. The merging
cold front is forecast to extend from 30N134W to beyond 26N140W
by Tue night. Expect increasing winds to 20-25 kt and building
seas of 8-10 ft across the NW waters, with the second front on