AXPZ20 KNHC 252127
Tropical Weather Discussion
NWS National Hurricane Center Miami FL
1605 UTC Tue Oct 25 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
Based on 1800 UTC surface analysis and satellite imagery through
Hurricane Seymour centered near 15.7N 116.4W at 2100 UTC about
600 nm southwest of the southern tip of the Baja California
peninsula moving west at 12 kt. Estimated minimum central
pressure is 954 mb. Maximum sustained winds are 115 kt with
gusts to 140 kt. Numerous moderate scattered strong convection
is within 75 nm of the center, and scattered moderate to strong
convection is elsewhere within 120 nm of the center. Seymour 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.
...INTERTROPICAL CONVERGENCE ZONE/MONSOON TROUGH...
The monsoon trough extends from 10N85W to 08N100W to 10N106W.
The ITCZ axis extends from 10N132W to 10N140W. Scattered
moderate convection is from 05N to 08N between 94W and 106W.
OFFSHORE WATERS WITHIN 250 NM OF MEXICO...
See the special features section for details on the persistent
Gulf of Tehuantepec gap wind event. 1022 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 to 48 hours, resulting in
a slight increase to 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
low pressure trough sets up across the gulf. Seas will be 2 ft
or less across most of the gulf through the weekend.
OFFSHORE WATERS WITHIN 250 NM OF CENTRAL AMERICA, COLOMBIA, AND
WITHIN 750 NM OF ECUADOR...
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.
REMAINDER OF THE AREA...
See the special features section for details on Hurricane
Seymour. A pre-frontal trough extends from 30N134W to 26N140W,
and a cold front from 30N138W to 29N140W. Fresh to strong
southwest winds precede both the front and pre-frontal trough.
Northwest swell to 11 ft are sweeping into the northwest part of
the discussion area. The front will move westward through early
Thursday, then dissipate from 30N125W to 21N131W 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.