000 AXPZ20 KNHC 261010 TWDEP Tropical Weather Discussion NWS National Hurricane Center Miami FL 1005 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 0600 UTC surface analysis and satellite imagery through 0900 UTC. ...SPECIAL FEATURES... Major Hurricane Seymour centered near 16.4N 119.0W AT 0900 UTC, or about 640 nm, or 1195 km southwest of the southern tip of the Baja California peninsula, moving west-northwest at 12 kt. Estimated minimum central pressure is 943 mb. Maximum sustained winds are 130 kt with gusts to 160 kt. Satellite imagery overnight continues to show an impressive hurricane, with a 15 nm wide eye most of the night, and numerous strong convection within 45 nm across the NW and 60 nm across the SE semicircles. Scattered to numerous moderate to strong convection was elsewhere within 120 nm across the NE and 60 nm across the SW semicircles. Seymour remains a category 4 hurricane on the Saffir-Simpson scale, and is the strongest of the 2016 Eastern Pacific season. Seymour has reached its peak intensity overnight, and is nearing cooler SSTs to the west and northwest. A gradual turn toward the northwest is expected today and then more NNW on Thursday and will lead to a very rapid weakening trend for Seymour. Seymour is forecast to become a post tropical remnant low by 72 hours. See latest NHC forecast/advisory under AWIPS/WMO headers MIATCMEP5/WTPZ25. 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 of 12N through Thursday. As a result, strong to near gale force northerly winds will continue to blow across and downstream 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 10N74W to 10N85W to 09N89W to 08.5N105W to 12N112W. The ITCZ extends from 12N123W TO 09.5N140W. Scattered moderate to strong convection is noted within 210 nm N and 240 nm S of the trough E of 90W. Scattered moderate isolated Strong convection is noted southwest of Seymour and within 120 nm S of the ITCZ between 123W and 133W. ...DISCUSSION... OFFSHORE WATERS WITHIN 250 NM OF MEXICO... See the special features section for details on the persistent strong Gulf of Tehuantepec gap wind event. 1018 mb high pressure centered off the coast of southern California near 31N121W is producing light to moderate anticyclonic winds across the waters west of the Baja California peninsula. Combined seas of 5 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 3 ft or less across the northern gulf through the weekend, and 3 to 5 ft across the south half. OFFSHORE WATERS WITHIN 250 NM OF CENTRAL AMERICA, COLOMBIA, AND WITHIN 750 NM OF ECUADOR... Offshore of the Gulf of Papagayo, fresh northeast to east winds will continue this morning before diminishing modestly this afternoon. 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 cold front extends across the NW waters from 30N133W to 25N140W. Fresh to strong south to southwest winds precede the front north of 27N. Northwest swell raising seas to 11 ft is sweeping into the northwest part of the discussion area behind the front. The front will move east southeastward through early Thursday, then stall as low pressure develops along the boundary near 30N129W, before dissipating from 30N124W to 22N130W Thursday and Friday. The low pressure is forecast to move northeast of the area Thursday. Winds ahead of 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 south of 23N and west of 130W with combined seas of 5 to 7 ft building to 6 to 9 ft on Thursday. $$ Stripling