000 AXPZ20 KNHC 040327 TWDEP Tropical Weather Discussion NWS National Hurricane Center Miami FL 0405 UTC Wed Nov 4 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... Gulf of Tehuantepec Gale Warning: Strong gales are ongoing across the Gulf of Tehuantepec this evening, with seas estimated to be 21 ft. The gales are due to a tight pressure gradient created by high pressure building north of the area over the Gulf of Mexico and across the eastern slopes of the Sierra Madre Oriental mountains. Swell generated from this Tehuantepec event will produce a large plume of 12 ft or greater seas that will extend about 500 nm southwest of the Gulf of Tehuantepec. Winds will gradually taper off to below gale force by midday Fri, as the high pressure north of the area weakens and shifts east. Marine interests transiting across or in the vicinity the Gulf of Tehuantepec should be aware of this gap wind event, and take necessary action to avoid hazardous marine conditions over the affected waters. Please refer to the latest High Seas Forecast issued by the National Hurricane Center at: https://www.nhc.noaa.gov/text/MIAHSFEP2.shtml for further details. Potential Heavy Rainfall event: Hurricane Eta over eastern Nicaragua along with a surge of moist southwesterly flow across the tropical eastern Pacific will support heavy to torrential rainfall across portions of Central America through mid week. Eta is likely to cause life-threatening flash flooding and river flooding across portions of Central America, along with landslides in areas of higher terrain. Eta is expected to produce rainfall accumulations of 15 to 30 inches (375 to 750 mm) across central and northern Nicaragua into Honduras, with isolated amounts of 35 inches (890 mm). Refer to statements provided by your national meteorological service for more details. Farther west, Tropical Storm Odalys is centered near 14.9N 117.2W at 04/0300 UTC moving WNW at 13 kt. Estimated minimum central pressure is 1006 mb. Maximum sustained wind speed is 35 kt with gusts to 45 kt. Strong convection is observed within 300 nm in the north quadrant of Odalys, and 180 nm in the west quadrant of the storm. Odalys is expected to strengthen as it continues to move WNW through Wed, then weaken to a depression and move more westward Thu as it reaches cooler waters. Odalys will become a remnant low by Sat ahead of a cold front moving into the area from the north. Please read the latest NHC Public Advisory at https://www.nhc.noaa.gov/text/MIATCPEP5.shtml and Forecast/ Advisory at https://www.nhc.noaa.gov/text/MIATCMEP5.shtml for more details. ...INTERTROPICAL CONVERGENCE ZONE/MONSOON TROUGH... The monsoon trough extends from 11N86W to 06N100W to 13N110W, then resumes SW of Odalys near 12N120W to 10N125W to 09N140W. Scattered moderate convection is observed from 10N to 12N between 123W and 126W. OFFSHORE WATERS WITHIN 250 NM OF MEXICO... Please refer to the Special Features section above for details on the Gulf of Tehuantepec Gale Warning. Of note, the 20-year climatology of the Tehuantepec gap wind events indicates that most gale-force events occurred during November and December while most events reaching storm-force occurred in January. Based on these updated records, the first storm-force wind event of each cold season can be expected to occur as early as mid- November. A ridge northwest of Baja California is supporting gentle to moderate northerly winds with seas 4 to 6 ft in NW swell. Seas will build to 8 ft south through southwest of the Revillagigedo Islands tonight through Wed as swell from the Tropical Storm Odalys enters the area, and Odalys makes its closes point of approach to the west of Clarion Island. Seas will build to 5 to 6 ft elsewhere off Baja California after mid week in a mix of NW swell and southerly swell emerging from Odalys. A cold front may bring strong NW winds to the waters off Baja California Norte and the Gulf of California Fri night. Gentle winds will persist south of Cabo Corrientes outside of the Gulf of Tehuantepec plume, with seas of 4 to 6 ft in mostly southerly swell. OFFSHORE WATERS WITHIN 250 NM OF CENTRAL AMERICA, COLOMBIA, and WITHIN 750 NM OF ECUADOR... Moderate to fresh south to southwest winds are south of the monsoon trough. Large seas generated by the gale force gap wind event in the Tehuantepec region are propagating across the offshore waters of Guatemala and El Salvador, mixing with SW swell and will maintain seas in the 10 to 15 ft range there through into Fri. Farther south, a combination of fresh SW winds and building SW swell support seas to 9 ft off western Panama and near the Azuero peninsula. As Hurricane Eta continues to move through Nicaragua and Honduras, expect fresh to occasional strong SW flow across the Pacific offshore waters from western Panama to Guatemala. REMAINDER OF THE AREA... High pressure dominates north of 20N, with the ridge extending SE and through 1021 mb high pressure centered near 32N127W. A weak cold front is drifting SE and gradually dissipating from near 30N135W to 26.5N140W. This pattern is supporting gentle to moderate NE winds over most area north of the monsoon trough, with isolated areas of fresh trades closer to the monsoon trough. Seas are 5 to 8 ft in NW swell to the W of 120W, except higher near Tropical Storm Odalys, and in an area of building seas between 15N to 20N west of 135W related to a large area of fresh trade winds farther west. Seas are also 8 ft in NW swell behind the dissipating front. Farther east, seas are 8 to 14 ft over tropical waters east of 110W due to NE swell emerging out of Tehuantepec and longer period SW swell moving into the region. The current trends will persist through mid week. Lingering swell from Odalys will mix with new NW swell expected to invade the waters north of 20N. Seas may reach as high as 14 ft in this NW swell north of 20N and east of 125W, following a strong front expected to move into the area. Meanwhile east of 120W, the gale to storm force wind event in Tehuantepec will finally be tapering off on Fri, with related seas subsiding accordingly. SW swell will persist however through weeks end. $$ Christensen