000 AXPZ20 KNHC 251455 TWDEP Tropical Weather Discussion NWS National Hurricane Center Miami FL 1521 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 meteorological analysis. Based on 1200 UTC surface analysis and satellite imagery through 1430 UTC. ...SPECIAL FEATURES... Hurricane Seymour centered near 15.6N 115.0W at 25/1500 UTC or 526 nm southwest of the southern tip of the Baja California peninsula moving west at 12 kt. Estimated minimum central pressure is 961 mb. Maximum sustained wind speed is 110 kt with gusts to 135 kt. Numerous moderate and scattered strong convection is within 75 nm of the center. Scattered moderate and isolated strong convection is elsewhere within 120 nm of the center, and within 90 nm southeast of a line from 15N113W to 12N122W. Seymour is forecast to maintain a west to west-northwest motion through tonight, then turn toward the northwest on Wednesday. Although the forecast track keeps Seymour just outside of the Mexican offshore waters zones, fresh to strong winds are expected in the southwest portion of zone PMZ015 through the afternoon, while seas of 8 to 14 ft will impact the entire zone, gradually subsiding through early Wednesday. 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 the offshore waters zone PMZ027. As a result, northerly winds will continue to pulse 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 up to 10 to 12 ft during the strongest winds. ...INTERTROPICAL CONVERGENCE ZONE/MONSOON TROUGH... The monsoon trough axis extends from 10N85W to 08N95W to 10N108W. The intertropical convergence zone axis extends from 10N133W to 10N140W. Scattered moderate and isolated strong convection is from 07N to 07N east of 83W, and also from 04N to 08N between 92W and 98W. ...DISCUSSION... OFFSHORE WATERS WITHIN 250 NM OF MEXICO... See the special features section for details on the persistent Gulf of Tehuantepec gap wind event. High pressure of 1020 mb is centered near 28.5N121W, 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 pressure center 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 upcoming weekend. Inside the Gulf of California, mainly gentle to moderate northerly flow will prevail through Thursday, with winds becoming light and southerly in the northern gulf by Thursday night through Saturday. Winds will become light and variable in the southern Gulf by early Friday as elongated northwest to southeast low pressure troughing oscillates its position in the vicinity of the gulf waters. Seas will be 2 ft or less across the northerly gulf, and 2 to 4 ft across the southern gulf through Thursday, then subsiding to 2 ft or less thereafter. 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 into early Wednesday. Elsewhere, gentle to moderate south to southwest winds are noted to the south of the monsoon trough, while mainly gentle west to northwest winds prevail to the north of the monsoon trough. Combined seas are in the 4 to 6 ft range, primarily in long period southeast swell which is dominating 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 30N137W to 27N140W, while a parent cold front is entering the area at 30N140W. Fresh to strong southwest to west winds precede the front near the pre-frontal trough, while northwest swells of 8 to 9 ft have already breached the northwest corner. The front will propagate to the east- southeast across the discussion waters to the north of 30N through the end of the weak. Elongated low pressure is forecast to form along the front by Wednesday night, translating northeast of the discussion waters by Thursday morning, impacting California Friday through the weekend. Associated winds are forecast to diminish to 20 kt or less by late Wednesday night into early Thursday, while the set of northwest swell continues to shift to the southeast, eventually mixing with seas generated by Seymour which will result in very 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. $$ LEWITSKY