477 AXPZ20 KNHC 312209 TWDEP Tropical Weather Discussion NWS National Hurricane Center Miami FL 2205 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 1800 UTC surface analysis and satellite imagery through 2130 UTC. ...SPECIAL FEATURES... Large Swell Event Across Eastern Pacific: Large NW swell of 12 to 14 ft is occurring north of 04N and west of 111W, and southeast of a line from 30N122W to 18N140W. Seas of 9 to 12 ft are NW of the line extending from 30N122W to 18N140W. Seas are 8 to 11 ft between 93W and 111W, the eastern portion of which is merging with swell from the Gulf of Tehuantepec gap wind event. This swell, in addition to another reinforcing NW swell from a cold front currently extending from 30N127W to 26N136W, will continue to spread south and east across the waters through Mon. Seas will subside below 12 ft by Mon evening. 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 06N125W to beyond 05N140W. Scattered moderate convection is noted from 02N to 07.5N between 79W and 90W, and from 03.5N to 10N between 107W and 130W. ...OFFSHORE WATERS WITHIN 250 NM OF MEXICO... Fresh to strong N winds are in the Gulf of Tehuantepec. Gentle winds are elsewhere, except for moderate NNW to N winds within 150 nm of the west coast of Baja California. Large NW swell is causing seas of 10 to 13 ft west of 108W, including the waters offshore of Baja California. Seas across the waters to the east of 108W are 7 to 10 ft in NW swell. In the Gulf of California, seas are 2 ft or less. For the forecast, the large NW swell impacting the Baja California offshore waters will subside below 12 ft tonight. Seas of 8 to 11 ft across most of the southwest and southern Mexico offshore waters will subside by Tue. A cold front will move through the Baja California offshore waters late tonight through Mon. This will keep seas around 8 to 10 ft west of Baja California through Tue before subsiding 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. The next cold front will reach the waters west of Baja California late Wed. Large NW swell will follow in behind this front, affecting the waters west of Baja California Wed night through the end of the work week. ...OFFSHORE WATERS WITHIN 250 NM OF CENTRAL AMERICA, COLOMBIA, AND WITHIN 750 NM OF ECUADOR... Fresh to near-gale force NE winds are occurring in the Gulf of Papagayo region according to the latest ASCAT satellite data. Seas are estimated at 8 to 9 ft. Seas of 7 to 9 ft in NW to N swell is noted offshore Guatemala and El Salvador due to a Gulf of Tehuantepec gap wind event. Moderate to fresh N winds are in the Gulf of Panama. 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 of 8 to 9 ft will continue through Wed. Meanwhile, a gap wind event in the Gulf of Tehuantepec will wind down by this evening, but seas of 7 to 8 ft will continue offshore Guatemala and El Salvador through mid-week due to continued NW swell over the area. Fresh N winds will pulse at night in the Gulf of Panama 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 high pressure ridging along 25N and lower pressure associated with the ITCZ is yielding fresh to strong NE trades from 05N to 21N and west of 128W. Moderate to locally fresh trades are noted elsewhere from the ITCZ to 22N, and west of 117W. South of the ITCZ and monsoon trough, winds are moderate or less. A cold front extends from 30N127W to 26N136W with fresh strong winds on both sides of the front, north of 28N between 124W and 132W. The sea conditions are described in the special features section above. 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 tonight. Elsewhere, the cold front will weaken by Mon evening as it approaches Baja California. Fresh to strong winds are expected north of 27N with this front through this evening. 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 strong winds and 9 to 13 ft seas to the area. The next cold front will enter the northwest waters Mon night, extend from near 30N129W to 26N140W Tue evening, and from near 30N118W to 25N130W by midday Wed. Large NW swell coming in behind this front will build seas to 12 to 15 ft across the waters north of 25N Tue night through Thu. $$ Hagen