000 AXPZ20 KNHC 292142 TWDEP Tropical Weather Discussion NWS National Hurricane Center Miami FL 2205 UTC Fri Dec 29 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... Gulf of Tehuantepec Gale Warning: Winds draining from the Chivela Pass are forcing fresh to strong N winds across the Gulf of Tehuantepec. By tonight, strong high pressure will build across the western Gulf of Mexico behind a strong cold front, increasing these winds to gale force. Gale force northerly gap winds are then expected to persist through Sat night, diminishing by early Sun morning. Seas will build to 12 ft by early Sat and peak near 13 ft Sat evening, then subside by Sun night across the region. Very Large Swell Event Across Eastern Pacific: A cold front stretches across the NW portion of the TAFB forecast waters from 30N127W to 21N140W. Fresh to strong winds are on both sides of the front north of 27N between 124W and 138W. Meanwhile, very large NW swell is associated with this system, with the highest seas of 23 to 25 ft north of 26N between 130W and 140W. Seas of 16 ft or greater are located NW of a line extending from 30N126W to 18N140W. The 12 ft seas extend as far south as 05N and as far east as 111W, including to the coastline of Baja California. The 8 ft seas extend even farther south to the Equator and as far east as 107W. The strong winds will continue through tonight as the front reaches 30N122W to 21N139W. The front will dissipate late Sat night over the Baja California offshore waters. However, the reinforcing swell will continue to spread south and east across the waters over the next few days. Seas will subside below 20 ft Sat morning. The 12 ft seas will subside by Sun evening, and continue to gradually subside through early next week. 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 10N85W to 04N98W to 05N102W. The ITCZ extends from 05N102W to 07N116W to beyond 07N140W. Scattered moderate convection is noted from 03N to 11N between 77.5W and 88W, from 02N to 08N between 109W and 126W, and from 04N to 09N between 128W and 140W. ...OFFSHORE WATERS WITHIN 250 NM OF MEXICO... See the Special Features Section above for details on a Gale Warning for the Gulf of Tehuantepec. A 1023 mb high pressure is centered to the west of the Baja California offshore waters near 24N123W. The ridging from this high extends across most of the offshore waters of Mexico. The pressure gradient between this high pressure and lower pressure over Mexico is supporting moderate to fresh NW winds across the central and southern Gulf of California with seas 3 to 5 ft. Meanwhile, gentle to moderate N winds are noted in the Baja California and southwest Mexico offshore waters. A large NW swell event is impacting the waters west Baja California with seas of 11 to 15 ft, confirmed by a recent altimeter satellite pass. Seas of 8 ft or greater in NW swell likely extend as far east as 107W. Elsewhere, gentle winds are noted with seas 5 to 7 ft in NW swell. For the forecast, moderate to fresh NW winds over the Gulf of California will diminish to light to gentle by Sat. Very large NW swell impacting the Baja California offshore waters will bring seas 11 to 15 ft through tonight. Another set of large NW swell will move across the Baja California offshore waters later tonight through Sun, bringing seas of 12 to 16 ft. Seas will subside Sun night into Tue night. ...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 3-6 ft in mixed swell. Scattered showers and thunderstorms are noted across the Costa Rica and Panama offshore waters. For the forecast, a building ridge north of the area will support fresh to strong NE gap winds over the Gulf of Papagayo region Sat night through Tue night. Meanwhile, gale-force gap winds in the Gulf of Tehuantepec will cause NW swell with seas 7-9 ft over the Guatemala and El Salvador offshore waters Sat night into Sun night. Fresh N winds are likely in the Gulf of Panama at night Sun night and Mon night. Otherwise, a weak pressure gradient will result in moderate or lighter winds across the rest of the area through early next week. ...REMAINDER OF THE AREA... See the Special Features Section above for details on the very large NW swell across most of the forecast waters. The weak pressure gradient between a 1023 mb high at 24N123W and the ITCZ is yielding moderate to fresh NE trades from the ITCZ to 17N and west of 115W. South of the ITCZ and monsoon trough, winds are moderate or less. Seas of 8 to 14 ft prevail across most of the area west of 107W and SE of a line from 30N125W to 16N140W. To the NW of that line, seas are 14 to 25 ft. East of 107W, seas are 5 to 7 ft. For the forecast, see the Special Features section above for details on the very large swell over much of our forecast waters. Elsewhere, weak high pressure will dominate leading to generally moderate to fresh trades through Sat. High pressure is expected to build across the northwest waters later in the weekend. This will enhance the NE trades between the ITCZ and 20N, and to the west of 127W from Sun through Tue, bringing fresh to strong winds and 8 to 12 ft seas to the area. $$ Hagen