000 AXPZ20 KNHC 310900 TWDEP Tropical Weather Discussion NWS National Hurricane Center Miami FL 1005 UTC Sun Dec 31 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: Strong high pressure centered over NE Mexico is forcing gale force winds across the Gulf of Tehuantepec, confirmed by ASCAT satellite data pass tonight. The gale force northerly gap winds are expected to diminish later this morning. Seas of 12 ft will begin to subside over the next few hours, then completely subside by Sun night across the region. Large Swell Event Across Eastern Pacific: Large WNW to NW swell, with seas of 12 to 15 ft confirmed by altimeter data tonight, is occurring north of 05N and west of 113W. The 8 ft seas extend southward beyond the Equator, and as far east as 100W, which is merging with swell from the Gulf of Tehuantepec gap wind event. This swell, in addition to another reinforcing NW swell from an incoming cold front across the NW waters from 30N135W to 28N140W, will continue to spread south and east across the waters through Mon. Seas will subside below 12 ft by Mon night. Please refer to the High Seas Forecast issued by the National Hurricane Center at https://www.nhc.noaa.gov/text/MIAHSFEP2.shtml for details on both special features. ...INTERTROPICAL CONVERGENCE ZONE/MONSOON TROUGH... The monsoon trough extends from the coast of Costa Rica near 09N84W to 06N91W. The ITCZ extends from 06N91W to 06N120W to beyond 04N140W. Scattered moderate convection is noted from 02N to 08N between 81W and 92W and from 03N to 09N between 106W and 134W. ...OFFSHORE WATERS WITHIN 250 NM OF MEXICO... See the Special Features Section above for details on a Gale Warning for the Gulf of Tehuantepec. Scatterometer data overnight confirmed gentle to moderate NNW winds prevailing across the Baja California offshore waters. Large NW swell is impacting the waters, ranging from 10 to 15 ft. The 12 ft seas dominate the waters north of Cabo San Lucas. In the Gulf of California, gentle winds and 1 to 2 ft seas are present. Light to gentle winds are elsewhere offshore Mexico outside of the Gulf of Tehuantepec. Seas across the southern and southwestern Mexico offshore waters are 7 to 10 ft within NW swell. For the forecast, the very large NW swell impacting the Baja California offshore waters will subside below 12 ft by this afternoon. Seas of 8 to 11 ft across most of the southwest and southern Mexico offshore waters will subside by Tue. A second cold front will move through the Baja California offshore waters late Sun night through Mon. This will keep seas around 8 to 10 ft in that region through Tue night. In the Gulf of Tehuantepec, fresh to strong winds will increase to strong to near gale force N winds by Mon evening. These winds will diminish by Tue night. Looking ahead, the next gap wind event in the Gulf of Tehuantepec should begin Wed night, with strong to near- gale force N winds possible through Thu night. ...OFFSHORE WATERS WITHIN 250 NM OF CENTRAL AMERICA, COLOMBIA, AND WITHIN 750 NM OF ECUADOR... Fresh to strong NE to E winds are occurring in the Gulf of Papagayo region. Seas of 6 to 8 ft in N swell is noted within the offshore Guatemala due to a Gulf of Tehuantepec gap wind event. Elsewhere, quiescent marine conditions dominate the waters with gentle to moderate winds and seas of 4 to 6 ft in mixed swell. For the forecast, a building ridge north of the area will support fresh to strong NE gap winds over the Gulf of Papagayo through Wed. Seas will build to 8 to 9 ft today and continue through Wed. Meanwhile, gale- force gap winds in the Gulf of Tehuantepec will cause NW swell with seas 7 to 9 ft over the Guatemala and El Salvador offshore waters through tonight. Fresh N winds will pulse at night in the Gulf of Panama tonight 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 large NW swell across most of the forecast waters. The pressure gradient between a 1022 mb high at 26N131W and the ITCZ is yielding fresh to strong NE trades from 07N to 23N and west of 125W. Moderate to locally fresh trades are noted elsewhere from the ITCZ to 22N, and west of 100W. South of the ITCZ and monsoon trough, winds are moderate or less. A cold front extends from 30N134W to 28N140W with fresh to locally strong winds behind it. Seas of 12 to 16 ft prevail across most of the area north of 07N and west of 112W in NW swell. Elsewhere west of 100W, seas are 8 to 12 ft. East of 100W, seas are 5 to 8 ft. For the forecast, see the Special Features section above for details on the large swell over much of our forecast waters. The current NW swell will subside to the 8 to 12 ft range across most of the area by this afternoon. Elsewhere, the cold front will reach from 30N124W to 25N134W Sun evening, then weaken by Mon evening as it approaches Baja California. Fresh to strong winds are expected north of 27N with this front. High pressure building across the northwest waters will enhance NE trades between the ITCZ and 20N, and to the west of 125W through most of the week, bringing fresh to strong winds and 8 to 12 ft seas to the area. $$ AReinhart