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Eastern North Pacific Tropical Weather Discussion

AXPZ20 KNHC 260258

Tropical Weather Discussion
NWS National Hurricane Center Miami FL
0405 UTC Wed Oct 26 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 0000 UTC surface analysis and satellite imagery through
0200 UTC.


Hurricane Seymour centered near 16.1N 117.7W at 0300 UTC about
620 nm southwest of the southern tip of the Baja California
peninsula moving west-northwest at 13 kt. Estimated minimum
central pressure is 943 mb. Maximum sustained winds are 130 kt
with gusts to 160 kt. Numerous moderate scattered strong
convection is within 90 nm of the center, and scattered moderate
to strong convection is elsewhere within 150 nm of the center,
except 90 nm in the southwest quadrant. Seymour is the strongest
hurricane of the 2016 Eastern Pacific season. It is expected
turn toward the northwest and start to weaken by Wed night. See
latest NHC forecast/advisory under AWIPS/WMO headers

Gulf of Tehuantepec Gale Warning...a locally tight pressure
gradient will persist across southeast Mexico between high
pressure located over eastern Mexico and lower pressure south
12N through Thursday. As a result, northerly winds will continue
to pulse at times to minimal gale force offshore of the Gulf of
Tehuantepec during the next few days, with the strongest winds
expected during the overnight and early morning hours. Seas will
build to around 12 ft during the period of strongest winds.


The monsoon trough extends from 12N86W to 08N101W to 11N107W.
The ITCZ axis extends from 09N131W to 08N140W. Scattered
moderate isolated strong convection is southwest of Seymour
within 60 nm of a line from 13N117W to 10N126W.



See the special features section for details on the persistent
Gulf of Tehuantepec gap high wind event. 1020 mb high pressure
centered off the coast of southern California near 33N121W is
producing light to gentle anticyclonic winds across the waters
west of the Baja California peninsula. Combined seas of 4 to 6
ft prevail north of 23N in northwest swell. The high will shift
slightly northeast during the next 24 hours, resulting in gentle
to moderate northwest winds across the offshore waters, which
will then persist into the weekend.

In the Gulf of California, gentle to moderate northerly flow
will prevail through Thursday, with winds becoming light and
variable by early Friday as an elongated northwest to southeast
trough sets up across the gulf. Seas will be 2 ft or less across
most of the gulf through the weekend.


Offshore of the Gulf of Papagayo, moderate to fresh northeast to
east winds will pulse late tonight to early Wednesday. Elsewhere
gentle to moderate south to southwest winds are found south of
the monsoon trough, while mainly gentle west to northwest winds
prevail to the north of the trough axis. Combined seas are 4 to
6 ft primarily in long period southwest swell which dominates
the offshore waters. These marine conditions will persist over
the next few days.


See the special features section for details on Hurricane
Seymour. A pre-frontal trough extends from 30N134W to 26N140W,
and a cold front from 30N135W to 27N140W. Fresh to strong
southwest winds precede both the boundaries. Northwest swell to
11 ft is sweeping into the northwest part of the discussion area
behind the front. The front will move westward through early
Thursday, then dissipate from 30N124W to 22N130W Thursday and
Friday. Elongated low pressure is forecast to form along the
front Wednesday night and move northeast of the area Thursday.
Winds associated with the front are expected to diminish below
20 kt early Thursday. The northwest swell will continue to
propagate southeast, and eventually mix with seas generated by
Seymour, resulting in a sizable area of confused seas.

Otherwise, weak northeast to southwest ridging ahead of the pre-
frontal trough and cold front will gradually dissipate through
Wednesday. Mainly moderate to locally fresh trades will prevail,
along with combined seas of 5 to 7 ft.