385 AXPZ20 KNHC 290938 TWDEP Tropical Weather Discussion NWS National Hurricane Center Miami FL 1005 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 0600 UTC surface analysis and satellite imagery through 0900 UTC. ...SPECIAL FEATURES... Gulf of Tehuantepec Gale Warning: Winds draining from the Chivela Pass are forcing fresh to strong N winds which will continue through today. By tonight, strong high pressure will build across the Gulf of Mexico as a strong cold front pushes across the W Gulf of Mexico. This will induce N gale- force gap winds over the Gulf of Tehuantepec. Gales are expected to persist through the weekend, diminishing by late Sat night into Sun morning. Seas will build to 12 ft later on Sat into Sat night and subside by Sun night across the region. Very Large Swell Event Across Eastern Pacific: A cold front stretches across the NW corner of the forecast waters from 29N132W to 24N140W. The latest scatterometer overnight showed strong winds ahead and behind the front, N of 26N. Meanwhile, very large swell is associated with this system, with the highest seas around 30 ft near 30N140W. The 12 ft seas extend as far south as 09N and as far east as 115W, including impacting the northern Baja California offshore waters. The 8 ft seas extend even farther south as 04N and as far east as 113W. The strong winds will continue through tonight as the front reaches 30N122W to 21N139W. The front will dissipate by 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 by Sat night. 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 off the coast of Colombia near 07N78W to 05N98W. The ITCZ extends from 05N98W to 06N120W to beyond 07N140W. Scattered moderate to isolated strong convection is noted from 03N to 10N between 79W and 88W. Scattered moderate convection is noted from 04N to 10N between 111W and 140W. ...OFFSHORE WATERS WITHIN 250 NM OF MEXICO... See Special Features Section above for details on a Gale Warning for the Gulf of Tehuantepec. A 1024 mb high pressure is centered to the west of the Baja California offshore waters near 27N122W. 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 Baja California waters N of Cabo San Lazaro with seas 12 to 18 ft. S of Cabo San Lazaro, seas range 8 to 12 ft. Elsewhere, light to gentle winds are noted with seas 5 to 7 ft in NW swell. No significant convection is noted at this time. For the forecast, high pressure over the U.S. Great Basin will support fresh NW winds over the Gulf of California today, becoming light by Sat. Very large NW swell impacting the Baja California offshore waters will bring seas 12 to 18 ft through tonight. Another set of large swell will move across the Baja California offshore waters later tonight through Sun. This swell event will bring seas 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 3-5 f in mixed swell. Scattered thunderstorms are noted across the Costa Rica and Panama offshore waters. Isolated thunderstorms are noted in the Gulf of Panama and along the Colombia coast. 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, a gale- force gap winds in the Gulf of Tehuantepec will cause NW swell with seas 7-9 ft over the Guatemala- El Salvador offshore waters Sat night into Sun 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 Special Features Section above for details on the very large NW swell across most of the forecast waters. The weak pressure gradient between a 1024 mb high at 26N122W and the ITCZ is yielding moderate to fresh NE trades from the ITCZ to 15N and west of 107W. South of the ITCZ and monsoon trough, winds are moderate or less. Seas are 6 to 10 ft across this area. 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 on in the weekend. This will enhance the NE trades south of 20N from Sun through Tue, bringing fresh to strong winds and 8 to 12 ft seas near the stronger winds. $$ AReinhart