000 AXPZ20 KNHC 300355 TWDEP Tropical Weather Discussion NWS National Hurricane Center Miami FL 0405 UTC Sat Dec 30 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 0000 UTC surface analysis and satellite imagery through 0330 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. In the next few hours, strong high pressure building across the western Gulf of Mexico behind a strong cold front will increase these winds to gale force. The gale force northerly gap winds are 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 afternoon, then subside by Sun night across the region. Strong winds will also briefly subside by Sun night. Very Large Swell Event Across Eastern Pacific: A cold front stretches across Eastern Pacific from 30N124W to 21N140W. Fresh to locally strong winds are noted behind the front, N of 27N. Meanwhile, very large NW swell is associated with this system, with the highest seas of 23 to 24 ft noted N of 27N between 127W and 136W. The 12 ft seas extend as far south as 04N and as far east as 109W, including to the entire coastline of Baja California. The 8 ft seas extend even farther south to the Equator and as far east as 107W. 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 the coast of Costa Rica near 09N84W to 04N96W. The ITCZ continues from 04N96W to 07N120W to beyond 06N140W. Scattered moderate convection is noted from 03N to 10N between 107W and 138W. ...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 1020 mb high pressure is centered to the west of the Baja California offshore waters near 25N122W. 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 NW winds across the central and southern Gulf of California with seas 2 to 4 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 14 ft. Seas of 8 ft or greater in NW swell likely extend as far east as 106W. Elsewhere, gentle winds are noted with seas 5 to 8 ft in NW swell. For the forecast, moderate 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 14 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 17 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. Seas will build to 8 ft Sun through Mon 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 will pulse at night in the Gulf of Panama from Sun night through Tue 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 21N 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 104W and SE of a line from 30N122W to 07N140W. To the NW of that line, seas are 14 to 23 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. $$ AReinhart