000 AXPZ20 KNHC 281604 TWDEP Tropical Weather Discussion NWS National Hurricane Center Miami FL 1605 UTC Mon Sep 28 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 1200 UTC surface analysis and satellite imagery through 1500 UTC. ...SPECIAL FEATURES... A broad area of disturbed weather is located a few hundred miles south of the southwestern coast of Mexico. Shower and thunderstorm activity associated with a small low embedded within this area has decreased since yesterday. However, environmental conditions are expected to gradually become more conducive for development and a tropical depression will likely form within the next two or three days. The disturbance is forecast to move generally westward for the next several days and then turn west-northwestward by the weekend. The latest Tropical Weather Outlook states that this system has a high chance of tropical cyclone formation through 48 hours. Refer to the latest Tropical Weather Outlook at www.hurricanes.gov for more details. Gulf of Tehuantepec gale warning: A strong gale force gap wind event is expected across the Gulf of Tehuantepec late Tue through Fri night as cold front moves across the Gulf of Mexico. Marine guidance suggests N winds blasting across the Tehuantepec waters Tue afternoon and quickly increasing to 30 to 45 kt by Tue night with seas building up to 16 or 17 ft. Please, read the latest NWS High Seas Forecast issued by the National Hurricane Center at website https://www.nhc.noaa.gov/text/MIAHSFEP@.shtml for more details. Of note, the 20-year climatology of the Tehuantepec gap wind events indicates that on average 16 gale-force events and 5 storm force-events occur in the Gulf of Tehuantepec each cold season. Most gale-force events occurred during November and December, while most storm-force winds occurred in January. Based on latest model trends and the present evolving synoptic scale setup, it appears that the forecast gale to near strong force wind event may supersede the previously recorded earliest start date of October 3rd. ...TROPICAL WAVES... The axis of a tropical wave is near 101W N of 03N, moving westward at 5 to 10 kt. Associated convection is described below. ...INTERTROPICAL CONVERGENCE ZONE/MONSOON TROUGH... The monsoon trough extends from 10N85W to 1007 mb low pres located near 13.5N104.5W to 11N125W to 10N140W. Scattered moderate isolated strong convection is noted from 07N to 12N between 92W and 101W, and from 10N to 16N between 105W and 109W. Scattered moderate convection is observed from 03N to 07N E of 80W to the coast of Colombia, from 10n to 12n between 110W and 118W, and from 08N to 10N W of 128W. OFFSHORE WATERS WITHIN 250 NM OF MEXICO... Please see above for more on the Gulf of Tehuantepec gale force gap wind event. Elsewhere, a weak ridge west of Baja California will maintain gentle to moderate NW to N winds across the region for the next few days. NW to N swell over the waters west of Baja California will subside through late today. Light to gentle southerly winds will prevail across the Gulf of California through this afternoon before shifting to the north. Elsewhere, light to gentle winds are generally expected across the waters from Las Tres Marias to Puerto Angel for the next several days. OFFSHORE WATERS WITHIN 250 NM OF CENTRAL AMERICA, COLOMBIA, and WITHIN 750 NM OF ECUADOR... Moderate southerly flow prevails S of the monsoon trough, with gentle winds north of the monsoon trough. Combined seas are currently 5 to 7 ft in a mix of wind waves and southerly swell. Long period SW swell is moving over the waters between Ecuador and the Galapagos Islands, with seas to 8 ft. This swell event will continue to propagate northward and reach the offshore waters of Central America today, where seas will build to 6 to 8 ft. In addition, seas generated by the gap wind event in the Tehuantepec region will propagate across the offshore waters of Guatemala and El Salvador on Wed. REMAINDER OF THE AREA... Please see Special Features section above for tropical cyclone potential. Cross equatorial SW swell, combined with a developing low pressure located near 13.5N104.5W is producing a large area of 8 to 10 ft from 05N to 12N between 100W and 120W. Sea heights of 8 to 9 ft are noted elsewhere across much of the waters S of 20N between 90W and 130W. These seas will gradually subside across the waters S of 20N and E of 120W by the middle of the week, except near the possible tropical cyclone. $$ GR