888 AXPZ20 KNHC 200952 TWDEP Tropical Weather Discussion NWS National Hurricane Center Miami FL 1005 UTC Fri Nov 20 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... Gulf of Tehuantepec Gale Warning: The gradient between a strong high pressure ridge over the Gulf of Mexico and lower pressure in the Pacific continues to support gale force northerly winds across the Tehuantepec region. Fresh to strong N to NE winds extend well offshore from Tehuantepec to near 11N100W. Peak seas to 14 ft prevail downwind of the Gulf. This long-lived gale event is expected to last through Mon morning. The leading edge of seas 8 ft or greater currently extend SW from the Gulf to near 104W and are forecast to reach as far west as 110W by Sat morning. 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 10N74W to 08N81W to 09N105W to 12N120W. The ITCZ begins near 12N120W and continues beyond the area at 09N140W. Scattered moderate isolated strong convection is noted N of 04N E of 80W. Scattered moderate isolated strong convection is noted from 07N to 12.5N between 101W and 111W. 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 southward across the Baja California offshore waters, extending from a 1031 mb high just off the northern California coast. The associated pressure gradient is producing moderate northerly winds across the waters from Punta Eugenia northward, and gentle to moderate northwesterly winds to the south. Wave heights are 5-7 ft in long-period northwest swell, except to 8 ft across the far northern waters. Little change in winds and seas are expected through Fri night. Moderate northerly winds prevail across central portions of the Gulf of California, where seas are 3-5 ft. These conditions will prevail through Sat and then improve modestly through Sun. An old frontal boundary across the waters offshore of southern California has become diffuse tonight. The remnants will move southward across northern Baja California and the northern Gulf of California tonight through Fri. As this happens, high pressure will build south-southeastward over the offshore waters and gradually shift westward through the weekend. This will produce generally moderate winds across the Baja offshore waters north of 20N, Fri night through Sun. OFFSHORE WATERS WITHIN 250 NM OF CENTRAL AMERICA, COLOMBIA, and WITHIN 750 NM OF ECUADOR... Moderate southwest winds are south of 07N 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 waves generated across the Tehuantepec region will propagate into the offshore waters of Guatemala and El Salvador through Fri before gradually subsiding through the weekend. REMAINDER OF THE AREA... The remnant low of Post-Tropical Cyclone Polo is centered near 17N122W moving W at 10 kt. The estimated minimum central pressure is 1010 mb. Recent scatterometer data showed maximum sustained wind speed is 25 kt with gusts to 35 kt. Scattered moderate convection is seen within 90 nm across the N semicircle of the center. Seas of 8 to 11 ft are found to the N and NW of the low. The remnants of Polo are expected to continue to move towards the west through late Friday and gradually weaken and then dissipate Friday night. A 1013 mb low pressure center currently just NW of the area has an attendant cold front that extends across the waters from 30N137W to beyond 27N140W. The low will weaken as it moves to near 33N137W by early Fri, with the cold front sweeping across the far northwest part of the area. The front will then become stationary and weaken Fri, before degenerating to a trough later Fri night. This low pressure system and front will generate large northwest swell entering the northwest part of the area on Fri, with seas building to 8-11 ft. Strong high pressure will build south- southeastward across the area through the weekend. The pressure gradient across the area west of 120W will support fresh NE winds between 11N and 20N, and seas generally 6-8 ft. The remnant low of Polo will move westward along about 16N through Sat to produce an area of higher winds and seas to 10 ft within 180 nm north of the system. Sat night into Sun these NE tradewinds will become fresh to strong as the pressure gradient tightens. Seas across this tradewind zone are expected to remain generally 7-10 ft in northwest swell through the weekend. $$ Stripling