000 AXPZ20 KNHC 271010 TWDEP Tropical Weather Discussion NWS National Hurricane Center Miami FL 1005 UTC Thu Oct 27 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... Hurricane Seymour has begun to weaken rapidly tonight, and is centered near 19.5N 122.1W 980 mb at 0900 UTC moving NNW at 10 kt. Maximum sustained winds have diminished to 80 kt with gusts to 100 kt. The center of Seymour is located satellite imagery on the SW edge of the deep convection as SW upper level wind shear is having a negative impact on the system. Scattered to numerous strong convection is within 90 nm across the northeast semicircle, while scattered moderate isolated strong convection is elsewhere within 180 nm NE and 60 nm SW semicircles. Seymour will turn northward today and continue to weaken rapidly as it moves into an increasingly unfavorable environment and cool SSTs. Seymour is expected to spin down and dissipate by 72 hours. through Friday. See latest NHC forecast/advisory under AWIPS/WMO headers MIATCMEP5/WTPZ25. Gulf of Tehuantepec Gale Warning...a high pressure ridge extending nearly N to S across eastern Mexico continues to produce a tight pressure gradient across southeast Mexico. As a result, strong northerly winds will continue to blow across the Gulf of Tehuantepec and spill downstream for the next severaldays. Winds will pulse to minimal gale force at night, with the strongest winds during the overnight into the early morning hours. Seas will build to 12 or 13 ft during the periods of gale force winds. ...INTERTROPICAL CONVERGENCE ZONE/MONSOON TROUGH... The monsoon trough axis extends from 10N85W to low pressure near 09N106W TO 12N112W...then resumes from low pressure near 15N130W TO 10N140W. Minimal convection associated with the trough. ...DISCUSSION... OFFSHORE WATERS WITHIN 250 NM OF MEXICO... See the special features section for details on a persistent Gulf of Tehuantepec gap wind event. High pressure centered SW of Tijuana near 30N120W continues to support gentle to moderate anticyclonic flow across waters offshore of the Baja California peninsula. Winds will slowly diminish this weekend, as a dying cold front moves east and the pressure gradient weakens. Seas of 5 to 7 ft in NW swell will subside to 4 to 5 ft by the weekend, then build to 6 to 9 ft by Sunday as another cold front and a new pulse of northwest swell moves across the northern waters. In the Gulf of California, gentle to moderate northerly flow will prevail today, 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 west 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 30N1329W to 20N140W. Fresh southwest winds N of 27N ahead of the front will diminish later this morning. Northwest swell producing seas to 10 ft is sweeping across the northwest part of the discussion area mainly behind the front. The front will move slowly east-southeast today, then temporarily stall as a low develops along it near 30N127W, then as the low moves north of the area Friday, it will drag the dying cold front further eastward. The associated NW swell will continue to propagate southeastward, and eventually mix with seas generated by Seymour, resulting in a sizable area of confused seas between 118W and 126W through Friday night. Otherwise, weak northeast to southwest ridging ahead of the cold front will gradually collapse today. 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 pulse of northwest swell. $$ Stripling