AXPZ20 KNHC 240246
Tropical Weather Discussion
NWS National Hurricane Center Miami FL
0405 UTC Mon Oct 24 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 0000 UTC surface analysis and satellite imagery through
Tropical storm Seymour is located near 14.4N 107.1W at 24/0300
UTC or about 320 nm...590 km SSW of Manzanillo Mexico, moving W-NW
or 290 deg at 13 KT. Maximum sustained winds are 45 kt with gusts
to 55 kt. Minimum central pressure is 1002 mb. Strengthening is
expected during the next 48 hours, and Seymour is forecast to
become a hurricane by Mon evening. The cyclone has become better
organized during the last hours with curved bands surrounding the
central convection. Currently, satellite imagery shows numerous
moderate to strong convection within about 75 nm E semicircle.
Numerous moderate isolated strong is in a band to the N and W of
the center and roughly covers from 12N to 17N between 105W and
108W. Although the forecast track keeps Seymour outside of the
forecast zones, fresh to strong winds and seas in the 8-11 ft
range are expected to affect the southern part of zones PMZ023
and PMZ025 tonight through late Monday, then PMZ015 Mon night and
Tue. For additional details, refer to the latest NHC
forecast/advisory under AWIPS/WMO headers MIATCMEP5/WTPZ25.
A gale warning will remain in effect for the Gulf of Tehuantepec
during the next 48 hours. Marine guidance continues to suggest
minimal gale force winds during the overnight and early morning
hours each day through probably the end of the week. By Thu night
into early Fri morning, the aerial extent of the gale force winds
will increase as high pres builds across the western Gulf of
Mexico. As result, the pres gradient will tighten across the
area. At that time, seas are expected to build to 13-14 ft.
...INTERTROPICAL CONVERGENCE ZONE/MONSOON TROUGH...
The monsoon trough extends across the Gulf of Panama near 08N79W
to 09N96W, then resumes W of T.S. Seymour at 15N110W to 1009 mb
low pres near 16N115W to 1009 mb low pres near 14N127W to 11N135W
to beyond 12N140W. Scattered moderate convection is from 12N to
14N between 116W and 119W.
OFFSHORE WATERS WITHIN 250 NM OF MEXICO...
See special features for T.S. Seymour and for the Tehuantepec area.
A weak high pres of 1014 mb is analyzed at 24N113W surrounded by
light anticyclonic winds across the waters W of the Baja California
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 later tonight. The high pres will dissipate in
about 24 hours, while another weak high pres center of 1015 mb
will remain nearly stationary near 25N125W.
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. By Mon evening, gentle to moderate NW winds will
dominate the waters S of 27N. Similar wind speeds are expected
between Los Cabos and Las Tres Marias Islands as well as W of Baja
OFFSHORE WATERS WITHIN 250 NM OF CENTRAL AMERICA, COLOMBIA, AND
WITHIN 750 NM OF ECUADOR...
Gulf of Papagayo: moderate to fresh NE winds and seas to around 6
ft are expected across and just downstream of the Gulf of Papagayo
tonight into early Mon morning.
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.
REMAINDER OF THE AREA...
A weak ridge dominates most of the north waters N of 20N. Under
the influence of this system, mainly light and variable winds are
noted per scatterometer data. Outside Seymour, two weak low pres
centers of 1009 mb are noted along the monsoon trough near 16N115W
and near 14N127W. An earlier Ascat passes showed very well the
cyclonic circulations associated with these lows.
Seas of 8-11 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 later tonight.
A cold front will enter the NW waters near 30N140W tonight and
will move across the NW waters on Monday, becoming stationary from
30N134W to 27N140W 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 30N132W 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 these fronts on Tue.