000 AXPZ20 KNHC 130337 TWDEP Tropical Weather Discussion NWS National Hurricane Center Miami FL 0405 UTC Tue Sep 13 2022 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 0000 UTC surface analysis and satellite imagery through 0300 UTC. ...INTERTROPICAL CONVERGENCE ZONE/MONSOON TROUGH... The monsoon trough axis extends from the coast of Nicaragua near 12N86W to 15N96W to a 1008 mb low pressure near 15N109W to 12N125W to beyond 08N140W. Scattered moderate to isolated strong convection is noted from 05N to 18N between 84W and 110W. Scattered moderate convection is noted from 07N to 15N between 111W and 140W. OFFSHORE WATERS WITHIN 250 NM OF MEXICO... Light to gentle variable winds are noted across the offshore waters of Baja California and in the Gulf of California. Seas range 5-6 ft seas off of Baja California with 1-3 ft seas in the Gulf. Meanwhile, earlier ASCAT data depicted fresh to strong winds across the Gulf of Tehuantepec, with seas 5-6 ft. Gentle to moderate winds prevail across the rest of the southern Mexico offshore waters. A 1008 mb low is analyzed just outside the Jalisco offshore waters near 16N109W. This low is bringing moderate winds with 6-7 ft seas in southerly swell across most of the southern Mexico offshore waters. Seas are up to 8 ft in the southern portion of the Guerrero offshore waters. Abundant deep layer tropical moisture is leading to scattered moderate convection across most the southwest Mexican offshore waters. For the forecast, winds across the Baja California offshore waters will increase moderate to fresh by Wed as high pressure builds across the area. The fresh to strong north to northeast winds in the Gulf of Tehuantepec will become light and variable by early Tue afternoon. A trough of low pressure located along the coast of southern Mexico is forecast to interact and merge with the disturbance off the southwestern coast of Mexico around midweek. Environmental conditions are expected to become more conducive for development by that time. A tropical depression is likely to form during the latter part of this week while the system moves slowly westward near the coast of southern and southwestern Mexico. Expect increasing winds and building seas offshore southern Mexico late in the week. This system has a low chance of formation in the next 48 hours and high chance in the next 5 days. OFFSHORE WATERS WITHIN 250 NM OF CENTRAL AMERICA, COLOMBIA, AND WITHIN 750 NM OF ECUADOR... Light to gentle winds are noted across the Central American offshore waters. Seas range 5-7 ft in S to SW swell. Gentle to moderate winds are noted off the Colombia offshores waters. Moderate to fresh southerly winds are noted across the offshores waters of Ecuador and the Galapagos Islands. Cross- equatorial long- period south to southwest swell continues to propagate through the South American forecast waters, with 5-7 ft seas across most of these waters. Wave heights up to 8 ft are noted in the Galapagos Islands and Ecuador offshore waters S of 00N. A moist and unstable environment is leading to scattered showers and thunderstorms across the majority of the Central American offshore waters. For the forecast, winds across the Central American offshore waters will increase to fresh by late Wed night as broad low pressure south of southwestern Mexico organizes. Winds over the Galapagos Islands and Ecuador offshore waters will diminish to gentle to moderate Wed, which will persist through Sat night. Wave heights are expected to build over the Ecuador and the Galapagos Islands offshore waters tonight through Tue, then slowly subside Wed into Thu. A very moist and unstable atmospheric environment will help maintain active weather across most of the offshore waters through the period. REMAINDER OF THE AREA... Relatively weak high pressure remains over the area north of the monsoon trough and west of 125W. The related light pressure gradient is allowing for gentle to moderate trade winds north of the monsoon trough and west of 105W, with seas ranging 6-7 ft. Moderate to fresh southerly winds are south of the monsoon trough. Wave heights of 7-9 ft in long- period south to southwest swell are noted S of 14N between 103W and 126W. An area of wave heights to 8 ft is over the far western part of the area from 12N to 17N and W of 135W due to persistent fresh northeast wind in that area. Low pressure along the monsoon trough near 12N130W is helping to increase the gradient there as well. Cross-equatorial swell is also lingering across the southern forecast waters, S of 03N. Seas range 8-9 ft in this area. Meanwhile, the remnant low tropical cyclone Kay is west of the Baja California Norte offshore waters near 27N121W, with a central pressure of 1013 mb. Earlier ASCAT data passes showed gentle to moderate winds near the low center. Wave heights of 6-7 ft are in the general area of the low. For the forecast, little change in marine conditions are expected over the next couple of days. The remnant low of Kay over the northeast part of the area will weaken to a trough west Baja California Norte on Tue. The weak high pressure is expected to continue over the next few days, with gentle to moderate winds north of the monsoon trough. Moderate to fresh southwest winds and associated wave heights of 8-9 ft in southerly swell will continue south of the monsoon trough through the next few days. These winds will likely increase to strong speeds east of about 113W on Thu as tropical cyclone genesis takes place offshore the southwestern coast of Mexico. Wave heights could build to 12 ft near the strongest winds toward the end of the week. The long- period cross-equatorial swell will continue through most of the week, with 8 ft seas subsiding toward the end of the week. The area of wave heights to 8 ft over the far western waters will subside late tonight. $$ AReinhart