941 AXPZ20 KNHC 271602 TWDEP Tropical Weather Discussion NWS National Hurricane Center Miami FL 1605 UTC Wed Dec 27 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 1530 UTC. ...SPECIAL FEATURES... Gale Warning Far NW Waters and Significant Very Large Swell Event: A cold front currently extending from 30N132W to 25N140W will move southeastward across the NW waters tonight into Thu, increasing winds in the far NW waters to gale force. SW gales are expected ahead of the front north of 28N west of 135W on Thu as well as W to NW gales behind the front north of 28N west of 135W on Thu night. A very large, 16-18 second NW swell associated with this front will spread southeastward and lead to seas in excess of 12 ft for most waters north of 10N and west of 115W on Thu before momentarily diminishing on Fri. An overnight 0700 UTC altimeter pass showed seas in excess of 30 ft just to the northwest of our border. A second reinforcing NW swell will arrive Thu night producing a peak of 30 ft seas along our NW corner waters Thu night. This will force seas of 12 ft or greater over most of our waters north of 07N west of 105W through Sat night before gradually diminishing. Please refer to the High Seas Forecast, issued by the National Hurricane Center, at https://www.nhc.noaa.gov/text/MIAHSFEP2.shtml, for details. ...INTERTROPICAL CONVERGENCE ZONE/MONSOON TROUGH... The monsoon trough extends from the coast of the Colombia-Panama border near 08N78W to 06N120W. The ITCZ extends from 06N120W to beyond 07N140W. Scattered moderate and isolated convection is occurring from 03N-08N west of 127W. Isolated moderate convection is occurring north of 05N east of 83W. ...OFFSHORE WATERS WITHIN 250 NM OF MEXICO... A 1022 mb high centered near 25N126W with a ridge extending northeastward to S California continues to dominate the offshore waters of Mexico. The pressure gradient between the ridge and lower pressures over Mexico supports moderate fresh NW winds in the central and S Gulf of California along with seas of 3-5 ft. Elsewhere, winds are moderate or weaker over the Mexican offshore waters. Seas are 7-8 ft in NW swell in the waters west and south of Baja California with 3-6 ft elsewhere. For the forecast, as high pressure builds southward from the U.S. Great Basin, fresh NW winds are expected over the Gulf of California tonight and again Thu night with gentle to moderate winds elsewhere. Over the Gulf of Tehuantepec, winds draining from the Chivela pass will force fresh to locally strong N winds Thu night into Fri morning. By Fri afternoon, a strong cold front pushing across the W Gulf of Mexico will induce a N gale-force gap wind event over the Gulf of Tehuantepec. Gales should continue through Sat night before steadily subsiding on Sun. Large NW swell impacting the waters west of Baja California today will gradually diminish through tonight. However, a very large NW swell with a 16-18 second period will reach the waters off of Baja California Norte tomorrow. This will produce 12-15 ft seas west of Baja California Thu through Fri, subsiding slightly on Fri night, then reinforced again on Sat and Sun. ...OFFSHORE WATERS WITHIN 250 NM OF CENTRAL AMERICA, COLOMBIA, AND WITHIN 750 NM OF ECUADOR... Quiescent marine conditions dominate the waters with gentle to moderate winds and seas of 3-5 ft. Locally higher winds and seas are present in scattered moderate convection that has developed offshore Panama in association with the monsoon trough. For the forecast, a weak pressure gradient will result in moderate or lighter winds through Sat night. A building ridge north of the area is likely to support fresh to strong NE gap winds over the Papagayo region Sat night into early next week. A gale-force gap wind event over the Gulf of Tehuantepec should cause large NW swell over the Guatemala-El Salvador offshore waters Sat night into early next week. ...REMAINDER OF THE AREA... See Special Features Section Above for details on gales that will develop tonight over the far NW waters and subsequent very large NW swell. A cold front currently extending from 30N132W to 25N140W. Fresh SW winds are ahead of this front N of 28N and between 128W-132W. Fresh W winds are occurring behind this front. Seas in this area of fresh and strong winds are 15-25 ft on both sides of the cold front in association with very large NW well. This long period NW swell continues to propagate further into the waters, and now encompasses waters NW of a line from 23N140W to 30N130W. N of the ITCZ, moderate to locally fresh trades prevail up to 18N, with locations N of 18N, excluding waters impacted by the aforementioned cold front, having light to gentle winds dominated by high pressure centered near 29N123W. Seas N of the ITCZ are 8 to 11 ft in long period NW swell. Elsewhere over the waters, winds are moderate or less and seas are generally 5 to 7 ft. For the forecast, the initial cold front will move SE through the area and dissipate by this evening. See the Special Features section above for details on the second cold front, that will cause gale conditions over portions of the waters. Elsewhere, weakening high pressure will dominate, leading to generally gentle to moderate winds through the week. A significant NW swell will spread SE and lead to seas in excess of 12 ft for most waters N of 10N and W of 120W Thu into the weekend. Seas in the far NW waters may peak as high as 30 ft Thu night into Fri night. $$ Landsea/Konarik