000 AXPZ20 KNHC 201535 TWDEP Tropical Weather Discussion NWS National Hurricane Center Miami FL 1605 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 1200 UTC surface analysis and satellite imagery through 1500 UTC. ...SPECIAL FEATURES... Gulf of Tehuantepec Gale Warning: High pressure along the eastern slopes of Mexico is enhancing northerly winds funneling through the Chivela Pass, which is supporting gale-force north to northeast winds in the Gulf of Tehuantepec, with seas peaking at around 13 ft. Gale conditions will continue through Thu evening, with winds forecast to diminish below gale force late Thu night. Strong to near-gale force winds will then continue through Fri night before diminishing Sat. Gulf of Papagayo Region Gale Warning: Gale force NE to ENE gap winds are expected to continue through this afternoon 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 by late this 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 today behind a frontal boundary. Seas with this swell event will peak in the 14 to 16 ft range over the waters north of 27N between 125W-135W late today 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 06N77W to 05N85W. The ITCZ continues from 05N85W to 05N140W. Scattered moderate convection is noted from 03N to 07N and E of 92W, and from 03N to 11N and W of 108W. ...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 winds are west of the Baja California peninsula, with mainly light to gentle winds across the rest of the open offshore waters. Seas are 4-6 ft west of Baja California, 2 ft or less over the Gulf of California, and 5-7 ft elsewhere over the open waters off Mexico, except 8-13 ft closer to the Tehuantepec region. 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 gale force winds are over the Gulf of Papagayo region, with fresh winds extending downstream of the Gulf to near 92W. Seas of 9-12 ft are over and downstream of the Gulf of Papagayo region. Overnight ASCAT satellite wind data showed strong NE gap winds in the Gulf of Fonseca and other gap wind areas extending about 90 nm offshore of portions of El Salvador and eastern Guatemala. Northwest swell generated by the Gulf of Tehuantepec gale-force gap wind event is supporting seas in the 8-9 ft range over the outer offshore waters of Guatemala and El Salvador. Overnight ASCAT satellite data depicts fresh to strong northerly winds over the Gulf of Panama. These winds likely extend downstream to 04N. Seas are 6 to 8 ft in the area. 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 through this afternoon. Fresh to strong winds will then continue Fri, then diminish by 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 will continue over the Gulf of Panama through tonight before diminishing to moderate to fresh Thu through Thu night. 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 cold front extends from 30N126W to 25N140W. To the NW of the front, fresh to strong NW to N winds and 9 to 11 ft seas prevail, in NW to N swell. Weaker winds and lower seas prevail SE of the front and north of 25N. Fresh trades prevail north of the ITCZ to 18N and west of 120W. Moderate trades prevail north of the ITCZ to 18N and east of 120W. Moderate winds prevail south of the ITCZ. Seas of 8-10 ft in NW to N swell are south of 13N and west of 110W. Seas of 5-8 ft are elsewhere over the discussion waters. For the forecast, winds south of the ITCZ will be in the moderate to fresh range through today, then mostly gentle speeds afterward. Low pressure will approach 30N from the north tonight. This will continue to support fresh to strong winds over the waters N of 28N and E of 134W tonight 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. $$ ERA