000 AXPZ20 KNHC 190325 TWDEP Tropical Weather Discussion NWS National Hurricane Center Miami FL 0405 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 0000 UTC surface analysis and satellite imagery through 0300 UTC. ...SPECIAL FEATURES... Tropical Storm Polo is centered near 16.9N 118.3W at 0300 UTC, moving WNW at 11 kt. The estimated minimum central pressure is 1004 mb. Maximum sustained winds are 40 kt with gusts to 50 kt. Satellite imagery shows that Polo is becoming 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 forecast to reach near storm force overnight. Wave heights are forecast to build to a maximum of 22 ft downstream of the Gulf of Tehuantepec near 14N96W by early Thu. 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 11N85W in Costa Rica to the 1008 mb remnant low of tropical cyclone Iota near 13N91.5W 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 13N between 97W and 100W. 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. This swell will decay slightly through Thu. A weakening stationary front that extends SW from southern California will dissipate west of Baja California Norte on Thu. Strong high pressure will build eastward as the front weakens, with the associated gradient expected to bring fresh northwest winds to the northern Gulf of California Sat night and Sun. OFFSHORE WATERS WITHIN 250 NM OF CENTRAL AMERICA, COLOMBIA, and WITHIN 750 NM OF ECUADOR... Moderate to fresh southwest winds are south of the monsoon trough east of 100W, with mainly gentle west to northwest winds north of the trough. Wave heights are generally 5-7 ft, except for 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 Thu. REMAINDER OF THE AREA... See the Special Features section above for details on Tropical Storm Polo. A weakening stationary front extends from southern California through 30N122W to 22N141W. The front will dissipate west of Baja California on Thu. 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 will approach the far northwest part of the area near 31N140W on Thu. The low will stall and weaken Thu night, 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 to 9 ft. Strong high pressure will build southward across the central and western sections of the area beginning late Fri, and nudge the trough westward on Sat. The pressure gradient between the building high pressure and forecast weakening Tropical Storm Polo should allow for wave heights in the range of 7-10 ft to exist west of about 126W and from 08N to 22N from late Fri through the weekend. $$ Mundell