000 AXPZ20 KNHC 160831 TWDEP Tropical Weather Discussion NWS National Hurricane Center Miami FL 1005 UTC Mon Oct 16 2023 Tropical Weather Discussion for the eastern Pacific Ocean from 03.4S to 30N, east of 120W including the Gulf of California, and from the Equator to 30N, between 120W and 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 0830 UTC. ...SPECIAL FEATURES... Gulf of Tehuantepec Gale Warning: High pressure has built along the eastern slopes of Mexico in the wake of a cold front which moved through the Gulf of Mexico. The pressure gradient between the area of high pressure and the eastern north Pacific monsoon trough is supporting gale- force gap winds, and seas to 10 ft, in the Gulf of Tehuantepec. Seas will peak near 15-16 ft tonight as winds peak near 40 kt. The area of high pressure will start to shift eastward. This will loosen the pressure gradient which will help diminish winds below gale- force Tue night into Wed morning. Meanwhile, seas in the Tehuantepec region will subside below 12 ft by Tue night. The pressure gradient will remain tight enough to support pulsing fresh to strong winds through the remainder of next week. Please read the latest NHC High Seas Forecast at website www.hurricanes.gov/marine for more details. South of Southwestern Mexico (EP90): A broad area of low pressure located a few hundred miles south of Acapulco, Mexico, is producing disorganized showers and thunderstorms. Winds associated with a Gulf of Tehuantepec gale- force gap wind event, mentioned above, will help generate spin for the developing area of low pressure. Environmental conditions are conducive for development of this system, and a tropical depression is anticipated to form within the next two or three days. This system is expected to move slowly westward and then turn northwestward late in the week offshore of the coast of southwestern Mexico. This system has a high chance of development in 48 hours. Please see hurricanes.gov for the latest NHC Tropical Weather Outlook. ...INTERTROPICAL CONVERGENCE ZONE/MONSOON TROUGH... The monsoon trough extends from 11N86W to low pres near 11.5N100.5W to 09N109W to 09N135W to 10N140W. Scattered moderate isolated strong convection is noted from 05N to 17N E of 107W, and within 120 nm south of the monsoon trough between 115W and 130W. Scattered moderate convection is noted from 05N to 12N between 135W and 140W. ...OFFSHORE WATERS WITHIN 250 NM OF MEXICO... Please see SPECIAL FEATURES section above for more on the upcoming Gulf of Tehuantepec gale- force gap wind event and EP90 that is being monitored for TC development. Aside from the Gulf of Tehuantepec and EP90, a ridge extends across the Baja California offshore waters. Gentle to moderate winds prevail west of the Baja California peninsula as well as the Gulf of California. Light to gentle winds are noted off SW Mexico. Seas are in the 4-6 ft range over the open waters off Mexico, and 2-4 ft over the Gulf of California. For the forecast, gale- force gap winds will prevail over the Gulf of Tehuantepec through Tue night into Wed morning. Fresh to strong winds will continue to pulse over the Tehuantepec region through the remainder of the week. Rough to very rough seas can be expected over this area through Wednesday. Gentle to moderate winds west of the Baja California peninsula and over Gulf of California will continue through Tuesday night before diminishing. Elsewhere, A broad area of low pressure located a few hundred miles south of Acapulco, Mexico, is producing disorganized showers and thunderstorms. Environmental conditions are conducive for development of this system, and a tropical depression is anticipated to form within the next two or three days. This system is expected to move slowly westward and then turn northwestward late in the week offshore of the coast of southwestern Mexico. This system has a high chance of tropical cyclone development in the next 48 hours. Looking ahead, an area of low pressure is expected to form south of the coasts of Guatemala and southern Mexico in a few days. Gradual development of the disturbance will be possible, and a tropical depression could form late this week or over the weekend while the system meanders over the far eastern portion of the basin.This system has a low chance of tropical cyclone formation in 48 hours and a medium chance in the next 7 days. ...OFFSHORE WATERS WITHIN 250 NM OF CENTRAL AMERICA, COLOMBIA, AND WITHIN 750 NM OF ECUADOR... Light to gentle winds are noted N of the monsoon trough, with gentle to locally moderate winds S of the monsoon trough. Seas are in the 4 to 5 ft range across the discussion waters. For the forecast, seas will increase moderate to rough today through Tue well offshore of Guatemala and El Salvador from swell generated from the Gulf of Tehuantepec gale- force gap wind event. Light to gentle winds will prevail north of the monsoon trough today. Winds will pulse moderate to fresh near the Gulf of Papagayo Tue and Wed night. Gentle to moderate winds will prevail south of the monsoon trough. Looking ahead, an area of low pressure is expected to form south of the coasts of Guatemala and southern Mexico in a few days. Gradual development of the disturbance will be possible, and a tropical depression could form late this week or over the weekend while the system meanders over the far eastern portion of the basin.This system has a low chance of tropical cyclone formation in 48 hours and a medium chance in the next 7 days. ...REMAINDER OF THE AREA... A 1022 mb high pressure center near 27N129W extends a ridge to near the Revillagigedo Islands. Light winds are in the vicinity of the high center. Gentle to moderate winds are elsewhere N of the monsoon trough. South of the monsoon trough, mainly light to gentle winds are noted. NW swell propagating across the NW waters is bringing seas of 8-9 ft over the NW waters. Elsewhere, seas of 5-7 ft prevail. For the forecast, the NW swell will slowly propagate while subsiding the next couple of days. By midweek, a large set of NW swell generated by a storm force low near 44N170W is expected to move into the NW waters, with seas peaking near 14-15 ft on Wed and Wed night. Seas greater than 8 ft associated to this swell will merge with seas generated by EP90 to cover much of the discussion waters W of 110W by the end of the week. $$ AL