000 AXPZ20 KNHC 282115 TWDEP Tropical Weather Discussion NWS National Hurricane Center Miami FL 2205 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 1800 UTC surface analysis and satellite imagery through 2100 UTC. ...SPECIAL FEATURES... Gale Warning Far NW Waters and Very Large Swell Event: A cold front that has reached our 30N140W corner will move southeastward and extend from 30N130W to 22N140W Fri morning. SW gales have been observed by the afternoon ASCAT scatterometer overpasses ahead of the front north of 28N west of 135W. W to NW gales behind the front north of 28N west of 135W are expected tonight. A very large, 15-17 second NW swell ahead of 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. A 1630 UTC altimeter pass measured seas around 20 ft along a line from 30N128W to 20N133W. Reinforcing NW swell will arrive tonight producing a peak around 32 ft seas along our NW corner waters. This will force seas of 12 ft or greater over most of our waters north of 05N west of 115W through Sat night before gradually diminishing early next week. Gulf of Tehuantepec Gale Warning: Winds draining from the Chivela Pass are forcing fresh to locally strong N winds through tomorrow. By tomorrow 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 through the weekend before subsiding by Sun afternoon. Peak seas during the period of gales will be around 12 ft on Sun. 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 Colombia-Panama border near 08N78W to 05N96W. The ITCZ extends from 05N96W to beyond 06N140W. Scattered moderate convection is occurring from 05N-09N between 126W-131W, from 04N-08N between 105W-111W, and from 04N-07N east 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 1025 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 over the Gulf of California along with seas of 2-4 ft. Elsewhere, winds are moderate or weaker over the Mexican offshore waters. Seas are 8-12 ft in NW swell in the waters west of Baja California Norte, 6-8 ft west and south of Baja California Sur with 3-6 ft elsewhere in the open Pacific. 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 impacting the waters off of Baja California Norte will produce 12-16 ft seas tonight through Fri. These seas will subside slightly Fri night, before being reinforced again Sat through Sun. Seas will diminish again Sun night into Tue. ...OFFSHORE WATERS WITHIN 250 NM OF CENTRAL AMERICA, COLOMBIA, AND WITHIN 750 NM OF ECUADOR... Quiescent marine conditions dominate the waters with gentle to moderate winds and seas of 3-5 ft. For the forecast, a weak pressure gradient will result in moderate or lighter winds into Sat. A building ridge north of the area should support fresh to strong NE gap winds over the Gulf of Papagayo region Sat night into Tue. Gale-force gap winds in the Gulf of Tehuantepec will cause large NW swell over the Guatemala- El Salvador offshore waters Sat night into Sun night. ...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. The weak pressure gradient between a 1025 mb high at 27N123W and the ITCZ is forcing only moderate to fresh NE trades from 08N-20N west of 110W. Seas are 8-12 ft across the remainder of the waters west of 110W due primarily to NW swell. Elsewhere across the Pacific, winds are gentle and seas are 4-7 ft. For the forecast, see the Special Features section above for details on the 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 Sat. From Sun into Tue, building high pressure near 30N will enhance the NE trades south of 20N. $$ Landsea