000 AXPZ20 KNHC 200355 TWDEP Tropical Weather Discussion NWS National Hurricane Center Miami FL 0405 UTC Wed Dec 20 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 0000 UTC surface analysis and satellite imagery through 0330 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 14 ft. A tight pressure gradient will support gale conditions through Thu night, with winds forecast to diminish below gale force on Fri. Gulf of Papagayo Region Gale Warning: Gale force NE gap winds are expected tonight through Wed morning in the Papagayo Region from near the border of Costa Rica and Nicaragua extending offshore to 87.5W and as far south as 10N. Seas will reach 10 to 12 ft within and downstream of these winds to about 09N90W. Winds will diminish below gale force Wed afternoon, but strong to near-gale force winds will continue through Thu night in the region. Eastern Pacific Significant Swell event: A set of large NW swell with seas greater than 12 ft will move into the northwest waters Wed. Seas with this swell event will peak in the 14 to 17 ft range over the waters north of 27N between 125W-135W late Wed and early Thu before starting to subside. Seas will subside below 12 ft early Fri. 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 extends from 07N78W to 04N84W to 05N100W. The ITCZ continues from 05N100W to 07N120W to 08N130W to 06N140W. Scattered moderate convection is noted from 03N to 09N between 83W and 97W, from 06N to 09N between 118W and 126W, and from 05N to 10N between 134W and 140W. ...OFFSHORE WATERS WITHIN 250 NM OF MEXICO... Please see the Special Features section for details on the ongoing Gulf of Tehuantepec Gale Warning. Aside from the gale in the Gulf of Tehuantepec, a weak pressure gradient prevails. Gentle to locally moderate winds are west of the Baja California peninsula, with mainly light to gentle winds across the rest of the open offshore waters. Seas are in the 4-7 ft range over the open waters off Mexico. Light to gentle winds and seas of 2 ft or less are over the Gulf of California. For the forecast, low pressure will approach far northern Baja California Norte from the W on Fri bringing fresh west to northwest winds. A large set of northwest swell will begin to impact the waters west of Baja California Norte Thu, spreading across the Baja California Sur offshores Fri before subsiding. Another set of NW swell will move into the Baja California Norte waters Sat night. ...OFFSHORE WATERS WITHIN 250 NM OF CENTRAL AMERICA, COLOMBIA, AND WITHIN 750 NM OF ECUADOR... Please see the Special Features section for details on the ongoing Gulf of Papagayo region gale warning. Strong to near gale force winds are over the Gulf of Papagayo region, with fresh winds extending downstream of the Gulf to near 93W. Seas of 8-10 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 8-10 ft range over the outer offshore waters of Guatemala and El Salvador. Fresh to strong north winds along with seas of 6-7 ft are over the Gulf of Panama and downstream to 05N. Gentle to moderate winds and seas of 5-6 ft are elsewhere south of the monsoon trough. For the forecast, strong to near gale force NE to E gap winds will continue in the Gulf of Papagayo region through Thu night, except to gale force tonight through early Wed. Fresh to locally strong winds will then continue Fri through Fri night. Winds will diminish Sat. NW swell generated by the Gulf of Tehuantepec gale-force gap wind event will impact the outer Guatemala and El Salvador offshore waters through Thu night. Fresh to strong north winds are expected over the Gulf of Panama through Wed night before diminishing. Elsewhere, winds are expected to be moderate or weaker for the next several days. ...REMAINDER OF THE AREA... Please see above for details on an upcoming significant swell event over the northwestern portion of the basin. A surface trough extends from 30N120W to 23N130W. To the NW of a line extending from 30N126W to 24N140W, moderate to fresh NW winds and 7 to 9 ft seas prevail. Weaker winds and lower seas prevail east of that line and north of 20N. Moderate to locally fresh trades are north of the ITCZ to near 15N. Gentle to moderate winds prevail south of the ITCZ. Seas of 8-10 ft in NW to N swell are south of 14N and west of 115W. Seas of 6-7 ft are elsewhere over the discussion waters. For the forecast, winds south of the ITCZ will be in the moderate to locally fresh range through Wed, then mostly gentle speeds afterward. Low pressure will approach 30N from the north Wed night. This will bring fresh to occasionally strong winds over the waters N of 28N and E of 134W Wed night through Fri. The low will also usher in a large set of NW swell to the area, discussed in the special features section above. Seas greater than 8 ft associated with this swell will propagate across the NW waters, reaching the waters NW of a line from 24N117W to near 09N140W Thu night. Thereafter, areal coverage of seas greater than 8 ft will start to decrease as the seas gradually subside. $$ Hagen