Tropical Weather Discussion

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Tropical Weather Discussion NWS National Hurricane Center Miami FL 0405 UTC Sat Dec 20 2025 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 0255 UTC. ...SPECIAL FEATURES... Gulf of Tehuantepec Gale Warning: The pressure gradient between a 1023 mb high pressure system over the SE United States and lower pressures in the deep tropics result in fresh to near gale-force northerly winds across the Gulf of Tehuantepec. Frequent gusts to gale force are expected tonight into Sat morning and seas will build to 8-9 ft (2.5-3 m). Fresh to strong winds will persist across the area through at least the middle of next week. Gale conditions will be possible, mainly at night, Mon through Wed as high pressure develops over the eastern slopes of the Sierra Madre mountains in Mexico. Rough seas are also likely to develop with the strongest winds. Please read the latest High Seas Forecast issued by the National Hurricane Center at website: https://www.nhc.noaa.gov/text/MIASFEP2.shtml for more information. ...INTERTROPICAL CONVERGENCE ZONE/MONSOON TROUGH... The monsoon trough extends from 09N84W to 09N100W. The ITCZ continues from 09N100W to 10N115W to beyond 06N140W. Scattered moderate convection is observed from 07N to 13N and between 113W and 130W. ...OFFSHORE WATERS WITHIN 250 NM OF MEXICO... High pressure north of the Gulf of Tehuantepec is supporting fresh to near gale-force northerly winds, along with frequent gusts to gale force and seas to 8 ft. Elsewhere, a 1021 mb high pressure system located well west of Baja California Norte extends a ridge to the Revillagigedo Islands. Moderate to locally fresh northerly winds and moderate seas are present west of Guadalupe Islands, while light to gentle winds and moderate seas prevail in the rest of the Baja California offshore waters. Light to gentle winds and slight to moderate seas are also prevalent in the remainder of the Mexican offshore waters. For the forecast, high pressure north of the Gulf of Tehuantepec will support fresh to near gale-force northerly winds and moderate to locally rough seas over the next several days. Winds may pulse to gale-force at night Mon through Wed. Elsewhere, for most waters, a relatively weak pressure gradient will lead to moderate or weaker winds and seas into the start of next week. Looking ahead, a cold front will approach the offshore waters of Baja California Norte by midweek possibly producing fresh to strong southerly winds and rough seas. ...OFFSHORE WATERS WITHIN 250 NM OF CENTRAL AMERICA, COLOMBIA, AND WITHIN 750 NM OF ECUADOR... A robust high pressure system north of the Caribbean is forcing fresh to locally strong easterly trade winds in the Gulf of Papagayo, extending downstream to 89W. Seas in these waters are 4-7 ft. Farther east, moderate to locally fresh northerly winds and seas of 2-4 ft are occurring in the Gulf of Panama. Elsewhere, moderate or lighter winds and moderate seas prevail. For the forecast, building high pressure north of the area will support fresh to strong NE to E winds, mainly during late night/early morning hours across the Gulf of Papagayo this weekend. In the Gulf of Panama, mainly gentle to moderate N winds are expected through early next week. Elsewhere, a weak pressure gradient will continue to only force moderate or weaker winds with slight to moderate seas across the remainder of the forecast waters into the start of next week. ...REMAINDER OF THE AREA... A 1021 mb subtropical ridge centered near 30N128W dominates the remainder of the tropical eastern Pacific. Moderate to locally fresh easterly winds and seas of 5-8 ft are noted over much of the basin west of 120W and north of the ITCZ. East of 120W and north of the ITCZ and monsoon trough, moderate easterly breezes and seas are prevalent. South of the monsoon trough and ITCZ and west of 100W, moderate to locally fresh southerly winds and seas of 4-8 ft prevail. Elsewhere, moderate or weaker winds and moderate seas are prevalent. For the forecast, high pressure will remain in control of the weather pattern across the waters N of ITCZ/Monsoon Trough and W of 110W through at least Sun, with little change in winds and seas. Starting Sun night, a surface trough is expected to form along the ITCZ near 120W enhancing deep convection and strengthening winds for a couple of days. At the same time, a cold front will reach the NW waters near 30N140W, bringing moderate to fresh SW winds ahead of the front and fresh N winds behind the front early next week. A swell event will follow the front, building seas to 8 to 12 ft beginning late on Mon.