000 AXPZ20 KNHC 051554 TWDEP Tropical Weather Discussion NWS National Hurricane Center Miami FL 1605 UTC Tue Dec 5 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 1200 UTC surface analysis and satellite imagery through 1530 UTC. ...SPECIAL FEATURE... Gulf of Tehuantepec Gale Warning: Strong high pressure over central Mexico is supporting northerly gale-force gap winds across the Gulf of Tehuantepec. This pattern will persist through mid week, with gales pulsing mainly at night. Gale force winds are expected to diminish completely by Thu morning with strong winds continuing through Fri. Seas may reach 10 to 12 ft downstream of the strongest winds during the overnight hours. Seas are expected to completely subside by Fri. Please read the latest High Seas Forecast issued by the National Hurricane Center at https://www.nhc.noaa.gov/text/MIAHSFEP2.shtml for more details. ...INTERTROPICAL CONVERGENCE ZONE/MONSOON TROUGH... The monsoon trough extends from the coast of Costa Rica/Panama near 09N84W to 08N109W and then from 08N114W to 06N124W. The ITCZ extends from 06N124W to beyond 05N140W. Scattered moderate convection is noted from 04N to 10N between 95W and 134W. ...OFFSHORE WATERS WITHIN 250 NM OF MEXICO... Please read the Special Features section for more information on the gale warning in the Gulf of Tehuantepec. A broad ridge extends across the offshore waters of Baja California from 1024 mb high pressure near 32N129W to the Revillagigedo Islands. The pattern is supporting gentle to moderate NW to N winds off Baja California and moderate to locally fresh NW winds over the Gulf of California. NW swell across the Baja California Norte waters is bringing 8 to 10 ft seas mainly over the waters beyond 60 nm, north of Cabo San Lazaro. Farther south, gentle to moderate breezes persist off southern Mexico with 5 to 6 ft combined seas in mixed swell. For the forecast, outside of the gap wind event in the Gulf of Tehuantepec, long- period NW swell will persist off Baja California and the Revillagigedo Islands through Sat. Seas as high as 12 ft could move across the Baja California Norte waters by Wed into Wed night. Reinforcing NW swell will arrive off Baja California Norte by Thu night into Fri, accompanying a cold front moving into the region. Swells will begin to subside later in the weekend. ...OFFSHORE WATERS WITHIN 250 NM OF CENTRAL AMERICA, COLOMBIA, AND WITHIN 750 NM OF ECUADOR... Fresh to strong NE to E winds are prevailing across the Gulf of Papagayo. Seas are 5 to 7 ft in this area. Gentle to moderate winds are noted elsewhere. Seas range 5 to 7 ft in the Guatemala and El Salvador offshore waters mostly within N to NW swell due to the influence of the Gulf of Tehuantepec gap wind event. Elsewhere, seas range 4 to 6 ft seas primarily in S to SW swell. Scattered thunderstorms are noted south of the monsoon trough off the coast of Colombia. For the forecast, high pressure building north of the region will support pulsing strong winds across the Gulf of Papagayo particularly at night. Seas will build well offshore of Guatemala by Wed into Thu due to swell generated by gale- force gap winds in the Gulf of Tehuantepec. Gentle to moderate winds are forecast elsewhere. Moderate combined seas will persist through mid week in a mix of SW and NW swell. ...REMAINDER OF THE AREA... High pressure dominates the waters north of 20N. Fresh to strong trade winds persist south of the ridge, mainly 08N to 25N west of 110W. Seas in this region are 9 to 13 ft, in a mix of seas due to the trade wind flow, and longer- period NW swell. A cold front stretches NW of the area with moderate to locally fresh SW winds ahead of it. A large reinforcing NW swell is beginning to move into the area, bringing 12 to 14 ft seas N of 28N and W of 138W. Combined seas of 6 to 9 ft cover much of the region elsewhere west of 110W, although with primarily S to SE swell south of 05N. Gentle to moderate winds and 5 to 7 ft seas are noted east of 110W. A trough extends along roughly 111W between 10N and 18N, associated with an upper trough to its northwest. Scattered moderate convection persists from 12N to 16N between 104W and 111W. For the forecast, the high pressure will dissipate into Wed as a weak cold front moves eastward across the waters north of 25N through Thu. This will allow trade winds to diminish slightly west of 110W through mid week. Large, long- period NW swell accompanying the front will move across the waters north of 10N and west of 120W through mid week. This swell will bring seas as high as 17 ft north of 25N and west of 130W today. East of 110W, the combination of the NW swell with shorter- period NE swell emerging from gap wind events and fresh E trade winds will support rough seas from 07N to 12N between 95W and 110W from Thu into Fri. $$ AReinhart/KRV/Mora