000 AXPZ20 KNHC 190915 TWDEP Tropical Weather Discussion NWS National Hurricane Center Miami FL 1005 UTC Thu Nov 19 2020 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... Tropical Storm Polo is centered near 17.1N 119.3W at 0900 UTC, moving W at 10 kt. The estimated minimum central pressure is 1005 mb. Maximum sustained winds are 35 kt with gusts to 45 kt. Satellite imagery shows that Polo is a sheared system with an exposed low level center west of remaining convection. Polo is forecast to gradually weaken and move westward, then degenerate to a remnant low on Fri. Please read the latest High Seas Forecast issued by the National Hurricane Center at website- https://www.nhc.noaa.gov/text/MIAHSFEP2.shtml and the latest Tropical Storm Polo NHC Forecast/Advisory and Public Advisory at www.hurricanes.gov for more details. Gulf of Tehuantepec Gale Warning: The gradient between strong high pressure over southern Mexico and low pressure in the Pacific is supporting gale force northerly winds across the Tehuantepec region. This event is forecast to be long-lived, with gale force winds expected through Sun. Wave heights will build to a maximum of about 20 ft downstream of the Gulf of Tehuantepec near 14N96W today. The leading edge of 8 ft or greater sea from associated swell is forecast to reach as far west as 110W by late Fri. Please read the latest NWS High Seas Forecast issued by the National Hurricane Center at website https://www.nhc.noaa.gov/text/MIAHSFEP2.shtml for more details. ...INTERTROPICAL CONVERGENCE ZONE/MONSOON TROUGH... The monsoon trough axis extends from the 1008 mb remnant low of tropical cyclone Iota near 13N92W to 12N93W to 11N119W. The ITCZ continues from 11N119W to 10N132W to 08N135W to beyond 08N140W. Scattered moderate to strong convection is seen from 10N to 14N between 97W and 101W. OFFSHORE WATERS WITHIN 250 NM OF MEXICO... A Gale Warning remains in effect for the Gulf of Tehuantepec. Please see the Special Features section above for details. A ridge extends across the offshore forecast waters west of Baja California, producing gentle to moderate northwesterly winds. Wave heights are 5-7 ft in long-period northwest swell. Little change in winds and sea heights is expected through Mon. A weakening stationary front that extends SW from San Diego California will dissipate west of Baja California Norte today. High pressure will build southeastward as the front weakens. OFFSHORE WATERS WITHIN 250 NM OF CENTRAL AMERICA, COLOMBIA, and WITHIN 750 NM OF ECUADOR... Moderate southwest winds are south of the monsoon trough east of 100W, with gentle west to northwest winds north of the trough. Wave heights are generally 5-7 ft, except 7-9 ft in mixed swell between 88W and 100W. Large seas generated in the Tehuantepec region will propagate into the offshore waters of Guatemala and El Salvador through tonight. REMAINDER OF THE AREA... See the Special Features section above for details on Tropical Storm Polo. A weakening stationary front extends from San Diego California through 30N122W to 22N140W. The front will dissipate west of Baja California today. An area of long-period northwest swell behind the front will shift eastward through Fri and gradually decay. A weak low pressure system and attendant cold front, currently near 33N144W, will approach the northwest part of the area later today. The low will stall and weaken tonight, then degenerate to a trough by late Fri. Large northwest swell will move into the northwest part of the area on Fri, with wave heights of 8-9 ft. High pressure will build southeastward late Fri, and nudge the trough westward on Sat. The pressure gradient between the high pressure and the remnant low of Polo should allow wave heights in the range of 7 to 10 ft to exist west of about 126W and from 08N to 22N through the weekend. $$ Mundell