000 AXPZ20 KNHC 280815 TWDEP Tropical Weather Discussion NWS National Hurricane Center Miami FL 1005 UTC Thu Dec 28 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 0800 UTC. ...SPECIAL FEATURES... Gale Warning Far NW Waters and Very Large Swell Event: A cold front will move southeastward across the NW waters today and reach from 30N130W to 22N139W Fri morning. SW gales are expected ahead of the front north of 28N west of 135W today as well as W to NW gales behind the front north of 28N west of 135W tonight. A very large, 16-18 second NW swell associated with the cold front is spreading southeastward and will lead to seas in excess of 12 ft for most waters north of 10N and west of 115W today. Reinforcing NW swell will arrive tonight producing a peak of 32 ft seas along our NW corner waters. This will force seas of 12 ft or greater over most of our waters north of 07N west of 115W through Sat night before gradually diminishing early next week. Gulf of Tehuantepec Gale Warning: Winds draining from the Chivela Pass will force strong N winds into Fri in the Gulf of Tehuantepec. By Fri night, a strong cold front pushing across the W Gulf of Mexico will induce a N gale-force gap wind over the Gulf of Tehuantepec. Gales should continue into Sun before subsiding Sun night. Seas during the period of gales will be 10 to 12 ft. Please refer to the High Seas Forecast, issued by the National Hurricane Center, at https://www.nhc.noaa.gov/text/MIAHSFEP2.shtml, for details. ...INTERTROPICAL CONVERGENCE ZONE/MONSOON TROUGH... The monsoon trough extends from the Costa Rica-Panama border near 09N82W to 05N95W. The ITCZ extends from 05N95W to beyond 06N140W. Scattered moderate convection is occurring from 03N-07N west of 130W and from 02N to 09N E of 85W. ...OFFSHORE WATERS WITHIN 250 NM OF MEXICO... See Special Features Section above for details on a Gale Warning for the Gulf of Tehuantepec. A 1022 mb high centered near 27N123W with a ridge extending northeastward to S California continues to dominate the offshore waters of Mexico. The pressure gradient between the ridge and lower pressures over Mexico supports moderate to fresh NW winds in the central and S Gulf of California along with seas of 3-5 ft. Elsewhere, winds are moderate or weaker over the Mexican offshore waters. Seas are 7-9 ft in NW swell in the waters west and south of Baja California with 3-6 ft elsewhere in the open Pacific as well as 1-2 ft in the N Gulf of California. For the forecast, high pressure over the U.S. Great Basin will force fresh NW winds over the Gulf of California tonight. Very large NW swell with a 16-18 second period will reach the waters off of Baja California Norte today. This will produce 12-16 ft seas west of Baja California tonight through Fri. These seas will subside slightly Fri night, before being reinforced again Sat through Sun. Seas will diminish again Sun night and Mon. ...OFFSHORE WATERS WITHIN 250 NM OF CENTRAL AMERICA, COLOMBIA, AND WITHIN 750 NM OF ECUADOR... Quiescent marine conditions dominate the waters with mainly gentle winds and seas of 3-5 ft. For the forecast, a weak pressure gradient will result in moderate or lighter winds into Sat night. A building ridge north of the area should support fresh to strong NE gap winds over the Gulf of Papagayo region Sun through early next week. Gale-force gap winds event the Gulf of Tehuantepec will cause large NW swell over the Guatemala-El Salvador offshore waters Sun into early next week. ...REMAINDER OF THE AREA... See Special Features Section above for details on gales that will develop tomorrow over the far NW waters and subsequent very large NW swell. A dissipating cold front currently extends from 30N128W to 26N138W. Fresh W winds are behind this front. Seas of 12 ft or more are occurring north of a line from 30N124W to 18N140W due to a long period NW swell, with peak seas reaching 20 ft. The pressure gradient between a 1022 mb high at 27N123W and the ITCZ is forcing fresh NE trades from 07N-16N west of 115W. Seas are 8-9 ft in this area, in mixed wind waves and NW swell. Elsewhere across the Pacific, winds are moderate or lighter and seas are 5-8 ft. For the forecast, the initial cold front will devolve into a surface trough today and dissipate tonight. See the Special Features section above for details on the second cold front, that will cause gale conditions over the NW corner of our waters and very large swell over much of our forecast waters. Elsewhere, weak high pressure will dominate leading to generally moderate to fresh trades through early next week. Even as the very large NW swell diminishes on Sun, seas of 8 ft or greater will reach southward to the equator and eastward to 100W on Sun through Mon. $$ Konarik