AXPZ20 KNHC 211600 TWDEP Tropical Weather Discussion NWS National Hurricane Center Miami FL 1605 UTC Thu Nov 21 2024 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 1200 UTC surface analysis and satellite imagery through 1500 UTC. ...SPECIAL FEATURES... Gulf of Tehuantepec Gale Warning: A ridge extending along the eastern slopes of the Sierra Madre Mountains in Mexico and the western Gulf of Mexico supports strong N winds of 40 kt across the Tehuantepec region. Peak seas are forecast to build to 16 ft or 17 ft by this afternoon. Gale force winds are forecast to persist through Sat morning. Large seas generated from this strong gap wind event will spread well away from the Tehuantepec area, with seas 8 ft or greater reaching as far south as 08N by Fri morning. Marine interests transiting across the Gulf of Tehuantepec Fri night into Sat should be aware of this upcoming gap wind event, and take the necessary action to avoid hazardous marine conditions over the affected waters. For more details, please read the latest NWS High Seas Forecast issued by the National Hurricane Center at website https//www.nhc.noaa.gov/text/MIAHSFEP2.shtml ...INTERTROPICAL CONVERGENCE ZONE/MONSOON TROUGH... The monsoon trough extends from 11N86W to a 1012 mb low near located near 15N101W to 10N115W to 09N130W. The ITCZ continues from 09N130W to beyond 09N140W. Scattered moderate convection is occurring from 08N to 11N between 118W and 130W. Similar convective activity is noted near 12N96W and near 13N115W. ...OFFSHORE WATERS WITHIN 250 NM OF MEXICO... Please refer to the Special Features section for information on the Gulf of Tehuantepec Gale event. A ridge anchored by a 1022 mb high pressure located near 28N124W dominates the offshore waters of Baja California. This pattern supports gentle to locally moderate NW to N winds across the Baja California offshore waters where seas are 5 to 7 ft. Elsewhere, the tight pressure gradient between the ridge and a trough in northwestern Mexico is supporting moderate to fresh NW winds in the Gulf of California. Seas are 4 to 6 ft across the central and southern part of the Gulf while seas of 2 to 4 ft area noted over the northern Gulf. Light to gentle winds and seas of 3 to 5 ft in mixed swell dominate the remainder of the Mexican offshore waters. For the forecast, gale force winds and rough to very rough seas will persist in the Tehuantepec area through Sat morning. High pressure will remain in control of the weather pattern across the waters W of the Baja California peninsula through the upcoming weekend supporting gentle to moderate NW winds. NW swell will build seas to 9 ft N of Punta Eugenia by this afternoon. This swell event will reach the outer offshore waters N of Cabo San Lazaro by Fri morning. ...OFFSHORE WATERS WITHIN 250 NM OF CENTRAL AMERICA, COLOMBIA, AND WITHIN 750 NM OF ECUADOR... Moderate to locally fresh SW winds are occurring offshore of Costa Rica southeastward through the coastal waters of Colombia, where seas of 4 to 6 ft are observed. Elsewhere, gentle to locally moderate W to SW winds and seas of 3 to 5 ft prevail across the remainder of the Central and South American offshore waters. For the forecast, seas generated in the Gulf of Tehuantepec gap wind event will impact the far western Guatemala offshore waters through Fri night. Moderate to locally fresh SW winds will continue in the offshore waters of Costa Rica through Colombia through Fri. Fresh to strong E to NE winds will then pulse in the Gulf of Papagayo Fri into Sun. Otherwise, moderate SE to SW winds will prevail across the offshore waters through this weekend. Looking ahead, rough seas in SW swell will reach the waters off the coast of Ecuador by early next week. ...REMAINDER OF THE AREA... A 1022 mb high is centered near 28N124W and ridging extends across the waters north of the monsoon trough. A tightening pressure gradient between the ridge and a cold front currently reaching 30N140W is supporting fresh to locally strong SW winds north of 28N and west of 130W. A new NW swell event is leading to seas of 8 to 11 ft in this region. Farther south, moderate E to NE winds are occurring along the southern periphery of the ridge and west of 110W, with locally fresh NE winds occurring near a 1009 mb low near 09N125W. Multiple sets of NW swell are promoting seas of 7 to 9 ft north of 15N, and pockets of 7 to 8 ft seas are noted along the monsoon trough, in a combination of NW and SW swell, along with shorter-period NE seas due to trade wind flow. South of the monsoon trough, gentle to moderate SE winds and seas of 5 to 7 ft prevail. For the forecast, high pressure will persist and shift southward across the waters through this weekend. The cold front located near 30N140W will move across the N waters through Sat while gradually weaken. Another long- period NW swell will reintroduce rough seas north of 25N through Sat. Looking ahead, a complex wave pattern will develop by Sun over the tropical eastern Pacific from 05N to 10N between 105W and 115W in a mix of NW and SW swell, along with a component of shorter period NE swell generated by the Tehuantepec gap wind event. SW swell to 8 ft will overtake the region south of 10N and east of 115W Mon and Tue. $$ GR