000 AXPZ20 KNHC 262122 TWDEP Tropical Weather Discussion NWS National Hurricane Center Miami FL 2205 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 1800 UTC surface analysis and satellite imagery through 2100 UTC. ...SPECIAL FEATURES... Hurricane Seymour centered near 17.5N 121.2W at 2100 UTC moving west-northwest at 11 kt. Estimated minimum central pressure is 958 mb. Maximum sustained winds are 110 kt with gusts to 135 kt. Numerous moderate scattered strong convection is within 60 nm of the center. Scattered moderate isolated strong convection is elsewhere within 150 nm in the northeast semicircle, and within 75 nm in the southwest semicircle. Seymour is forecast to turn northwest tonight, then north on Thursday, with a decrease in forward speed. It is expected to weaken rapidly as it moves into an unfavorable environment Thursday and Friday. 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 the weekend. As a result, northerly winds will continue to pulse to minimal gale force the next several days, with the strongest winds likely during the overnight into the early morning hours. Winds are forecast to peak to up to 40 kt late tonight into early Thursday as the pressure gradient tightens even more. Seas will build to 12 ft during the gale force winds, except up to 14 ft late tonight and early Thursday. ...INTERTROPICAL CONVERGENCE ZONE/MONSOON TROUGH... The monsoon trough axis extends from 09N84W to low pressure near 08N107W 1010 mb to 12N114W, then resumes from low pressure near 15N120W 1011 mb to 11N140W. Scattered moderate convection within 150 nm southeast of the trough axis between 127W and 135W. ...DISCUSSION... OFFSHORE WATERS WITHIN 250 NM OF MEXICO... See the special features section for details on the persistent Gulf of Tehuantepec gap wind event. 1019 mb high pressure is centered west of Tijuana near 32N121W. This high will continue to support gentle to moderate anticyclonic flow across waters offshore of the Baja California peninsula, diminishing to gentle throughout this weekend, as the pressure gradient weakens due to the approach of a dying cold front. 5 to 7 ft seas will subside to 4 to 5 ft by the weekend, then build to 6 to 9 ft by Sunday as a new set of northwest swell arrives. 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 the northern gulf through the weekend, and 2 to 4 ft across the southern half. OFFSHORE WATERS WITHIN 250 NM OF CENTRAL AMERICA, COLOMBIA, AND WITHIN 750 NM OF ECUADOR... Gentle to moderate south to southwest winds are found south of the monsoon trough, while mainly gentle west to northwest winds prevail north of the trough axis. Combined seas are 4 to 7 ft, primarily in long period southwest swell. Seas will decay to 3 to 5 ft this weekend. REMAINDER OF THE AREA... See the special features section for details on Hurricane Seymour. A cold front extends across the northern waters from 30N131W to 23N140W. Fresh southwest winds within 60 nm east of the front, north of 26N will diminish tonight. Northwest swell to 11 ft is sweeping across the northwest part of the discussion area mainly behind the front. The front will move slowly east- southeast through early Thursday, temporarily stall as a low pressure area develops along it near 29N129W, then the low will move northeast of the area Thursday night pulling the trailing but dying cold front eastward. 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 cold front will gradually dissipate tonight. Moderate to fresh trades will prevail outside of the influences of the front and Seymour, with combined seas of 4 to 6 ft. A new cold front will reach the area near 30N140W this weekend, bringing a reinforcing set of northwest swell. $$ Mundell