000 AXPZ20 KNHC 282115 TWDEP Tropical Weather Discussion NWS National Hurricane Center Miami FL 2205 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 1800 UTC surface analysis and satellite imagery through 2100 UTC. ...SPECIAL FEATURES... A 1008 mb low pressure is analyzed near 13.5N105W. Showers and thunderstorms associated with this system have increased during the past few hours and have recently begun to show signs of organization. Additional development is expected and a tropical depression will likely form during the next couple of 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. High pressure building behind the front will provide a very tight pressure gradient over the area, and bring an increase in winds funneling into the Gulf of Tehuantepec. Winds will rapidly increase to gale force by late Tue, reaching 30-40 kt by Tue night. At that time, seas will build to 17 or 18 ft. Swell generated from this event are forecast to reach 100W on Wed. 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, this forecast event most likely will 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 1008 mb low pressure located near 13.5N105W to 11N125W to 09N140W. Scattered moderate isolated strong convection is noted from 10N to 17N between 102W and 110W. Scattered moderate convection is observed from 06N to 10N between 84W and 88W, from 06N to 10N between 91W and 101W, and from 09N to 12N between 110W and 117W. 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. Gentle to moderate northerly winds will prevail across the northern Gulf of California through Tue night while mainly light to gentle winds are expected elsewhere across the Gulf most of the forecast period. Elsewhere, light to gentle winds are generally expected across the waters from Las Tres Marias Islands 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 later 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 beginning on Wed morning. REMAINDER OF THE AREA... Please see Special Features section above for tropical cyclone potential. Cross equatorial SW swell, combined with a developing low pressure system located near 13.5N105W is producing a large area of 8 to 10 ft from 06N 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 125W. 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