000 AXPZ20 KNHC 180934 TWDEP Tropical Weather Discussion NWS National Hurricane Center Miami FL 1005 UTC Mon Dec 18 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 0915 UTC. ...SPECIAL FEATURES... Gulf of Tehuantepec Gale Warning: The pressure gradient between high pressure along the eastern slopes of Mexico and the eastern north Pacific monsoon trough is supporting gale-force north to northeast winds of 30-40 kt in the Gulf of Tehuantepec, with seas peaking at around 12 ft. A tight pressure gradient will support gale conditions through much of the week. Seas with this latest gale-force gap wind event are forecast to peak near 14 ft late tonight and on Tue. Eastern Pacific Significant Swell event: Seas peaking to 14 ft in northwest swell generated from the gale wind event of the past few days are over the western part of the area north of 13N and west of 130W. A subsiding trend will continue with these seas today as they are expected to lower below 12 ft. Please read the latest NWS 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 axis extends from northwestern Colombia to across northern Panama and to 09N83W to 06N92W to 06N100W. The ITCZ extends from 06N100W to 07N112W to 07N125W to 06N132W and to 07N140W. Numerous moderate to strong convection is within 120 nm south of the ITCZ between 116W-125W. Scattered moderate to isolated strong convection is within 120 nm south of the ITCZ between 125W-128W. Scattered moderate convection is within 60 nm north of the ITCZ between 116W-128W. ...OFFSHORE WATERS WITHIN 250 NM OF MEXICO... Please see the Special Features section for details on an ongoing Gulf of Tehuantepec Gale Warning. Aside from the Gulf of Tehuantepec, moderate northwest winds, and seas of 1-3 ft, are over the Gulf of California. A weak pressure gradient dominates the Mexican offshore waters outside of the Gulf of Tehuantepec, with moderate or weaker winds across the rest of the offshore waters. Seas are in the 4-7 ft range in long- period west to northwest swell off Baja California Norte, and 4-5 ft elsewhere. For the forecast, moderate northwest winds over the Gulf of California will gradually diminish through the week. Large NW swell over the outer offshore forecast waters of Baja California between Cabo San Lazaro and Punta Eugenia will subside on Tue. Low pressure may approach far northern Baja California Norte from the W on Fri bringing fresh west to northwest winds to the corresponding offshore waters. In addition, a large set of northwest swell will begin to impact those same waters with large building seas beginning Thu. ...OFFSHORE WATERS WITHIN 250 NM OF CENTRAL AMERICA, COLOMBIA, AND WITHIN 750 NM OF ECUADOR... Moderate to fresh northeast to east winds, and seas of 4-5 ft, are over and downstream of the Gulf of Papagayo region. Northwest swell generated by the Gulf of Tehuantepec gale-force gap wind event is supporting seas in the 6-8 ft range over the outer offshore waters of Guatemala and El Salvador. Moderate to fresh north winds and seas of 4-6 ft are over the Gulf of Panama. Moderate to fresh north winds and seas of 3-5 ft are elsewhere across the discussion waters. For the forecast, fresh to strong northeast to east winds in the Gulf of Papagayo will continue through the week, reaching near gale force tonight tonight through Wed. NW swell generated by the Gulf of Tehuantepec gale-force gap wind event will impact the outer Guatemala and El Salvador offshore waters for much of the week. Moderate to fresh north winds are over the Gulf of Panama. These winds are expected to continue well into the week, reaching strong speeds tonight through early Wed. Elsewhere, winds are expected to be moderate or weaker for the next several days. ...REMAINDER OF THE AREA... Please see above for details on a soon to end significant swell event over the western portion of the basin. A 993 mb gale center is located well north of the discussion area near 38N133W. Only fresh southwest to west winds on the most outer periphery of its cyclonic circulation are impacting the waters north of 29N and west of 124W. Gentle to moderate winds are elsewhere north of 24N and west of 121W. Moderate to fresh winds are north of the ITCZ to near 15N. Gentle to moderate winds are south of the monsoon trough. Light to gentle winds are elsewhere over the discussion waters. Outside of the area of 12 ft seas, seas greater than 8 ft are found over much of the waters north of 07N and west of 120W. Seas of 5-7 ft prevail elsewhere over the discussion waters. For the forecast, winds south of the ITCZ will be in the moderate to fresh range going into midweek. Swell from the Tehuantepec gap wind event has spread westward, with seas of 8-9 reaching to near 104W. The swell will later today. The 8 ft seas from the northwest swell over the western waters will spread eastward to cover much of the waters west of 120W today before starting to subside below 8 ft. A new set of northwest swell will move into the northwest waters at midweek. Seas with this swell will peak near 14 or 15 ft over the northern waters north of 29N between 125W-132W early Thu before starting to subside. $$ Aguirre