000 AXPZ20 KNHC 140941 TWDEP Tropical Weather Discussion NWS National Hurricane Center Miami FL 1005 UTC Wed Sep 14 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 0600 UTC surface analysis and satellite imagery through 0930 UTC. ...INTERTROPICAL CONVERGENCE ZONE/MONSOON TROUGH... The monsoon trough extends from the coast of Costa Rica near 10N86W to 14N97W to a 1009 mb low near 15N111W to 13N125W to beyond 10N140W. Scattered moderate to isolated strong convection is noted from 05N to 16N between 87W and 113W. Scattered moderate convection is noted from 07N to 15N between 124W and 135W. OFFSHORE WATERS WITHIN 250 NM OF MEXICO... Light to gentle variable winds prevail across the offshore waters of Baja California and most of the Gulf of California. Moderate to locally fresh winds are likely occurring in the northern Gulf. Seas range between 4-6 ft off of Baja California and 1-3 ft in the Gulf, with seas near 4 ft in the northern Gulf. Light to gentle variable winds prevail across most of the SW Mexico offshore waters with 6-7 ft seas in S to SW swell. The overnight ASCAT pass depicted locally moderate winds in the Gulf of Tehuantepec. Moderate to locally fresh winds are noted in the outer offshore waters of Jalisco to Guerrero associated with a 1009 mb low near 16N109W and seas approaching 8 ft. Scattered showers and thunderstorms are observed across most the SW Mexican offshore waters, particularly in Michoacan to Oaxaca. For the forecast, winds across the Baja California offshore waters will increase moderate to fresh later today and into tonight as high pressure builds across the area. A large area of disorganized showers and thunderstorms a couple of hundred miles off the coast of southern Mexico is associated with a trough of low pressure. Environmental conditions are expected to become more conducive for development, and a tropical depression is likely to form toward the end of the 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 and into the weekend. 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... Gentle to moderate SW to W winds are noted across the Central American and Colombia offshore waters north of the monsoon trough. South of the monsoon trough, winds are moderate to locally fresh. Seas are 5-7 ft in SW to S swell across the Central American and Colombia offshores. Seas are 6-8 ft across the Ecuador and Galapagos Islands offshore waters due to a cross- equatorial southerly swell. Strong thunderstorms are noted off the Colombia coast and in the Gulf of Panama, N of 03N and E of 81W. Scattered showers and thunderstorms are also noted across the rest of the Central America offshore waters due to a moist and unstable environment interacting with the monsoon trough. For the forecast, winds across the Central American offshore waters will increase to fresh later today and into tonight as a broad low pressure south of southwestern Mexico organizes over the next few days. Winds over the Galapagos Islands and Ecuador offshore waters will diminish to gentle to moderate today and continue into the weekend. The cross- equatorial swell across the Ecuador and Galapagos Islands offshore waters will slowly subside by Thu night. A very moist and unstable atmospheric environment will help maintain active weather across most of the offshore waters over the next few days. REMAINDER OF THE AREA... Relatively weak high pressure remains over the area north of the monsoon trough and west of 120W. The related light pressure gradient is allowing for mostly gentle to moderate trade winds north of the monsoon trough and west of 120W, with seas ranging 5-6 ft. ASCAT depicts a trough of low pressure along the monsoon trough near 13N133W with fresh winds north of it. Seas are 7 ft in this area. A trough extends in the northeast waters from 27N117W to 20N122W with moderate NE winds north of it. Moderate to fresh southerly winds are south of the monsoon trough. Fresh to locally strong SW winds are noted on ASCAT south of a 1009 mb low near 16N109W with seas 8-9 ft. Wave heights of 8 ft in long- period south to southwest swell are noted on earlier altimeter passes from 08N to 14N between 104W and 123W. Cross- equatorial southerly swell continues to linger across the southern waters S of 01S. For the forecast, the weak high pressure will lead to gentle to moderate winds north of the monsoon trough through Thu, with winds becoming moderate to fresh by Thu night through Sat. This will cause seas to build to near 8 ft. Moderate to fresh southwest winds and associated wave heights of 8-9 ft in southerly swell will continue south of the monsoon trough over the next few days. These winds will likely increase to strong speeds east of 110W later in the week as tropical cyclone genesis takes place offshore the southwestern coast of Mexico. Wave heights could build to near 12 ft near the strongest winds. The long- period cross- equatorial swell will continue through the rest of the week, with the 8 ft seas subsiding by the weekend. $$ AReinhart