000 AXPZ20 KNHC 200147 TWDEP Tropical Weather Discussion NWS National Hurricane Center Miami FL 0405 UTC Fri Dec 20 2024 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 0000 UTC. ...SPECIAL FEATURES... Gulf of Tehuantepec Gale Warning: High pressure building into the western Gulf of Mexico and adjacent northeastern Mexico will continue gale-force gap winds in the Gulf of Tehuantepec through Sun morning. Seas during this time will peak at 12 to 16 ft. The high pressure will shift east Sun, allowing winds to diminish to below gale force for the end of the weekend into early next week. Please see the latest NWS High Seas and Offshore Waters Forecasts issued by the National Hurricane Center at website: https://www.nhc.noaa.gov/text/MIAHSFEP2.shtml and https://www.nhc.noaa.gov/marine/offshores_eastpac.php for more details. Significant NW swell: A complex and powerful low pressure well N of the area will generate at least a couple rounds of large NW swell that will spill into the area into early next week. The first significant set is moving SE of 30N140W now, and will lead to seas of 12 to 20 ft N of 25N and W of 135W Fri, with seas above 12 ft N of 15N and W of 125W Sat. Seas may peak near 25 ft around 30N140W Fri night into Sat. These very rough seas are forecast to propagate into coastal waters W of Baja California for the end of the weekend into early next week, as the second round of reinforcing NW swell sweeps into the NW waters. Please see the latest NWS High Seas Forecast issued by the National Hurricane Center at website: https://www.nhc.noaa.gov/text/MIAHSFEP2.shtml for more details. ...INTERTROPICAL CONVERGENCE ZONE/MONSOON TROUGH... A monsoon trough curves from the coast of Costa Rica near 10N83.5W to 05N95W. An ITCZ continues westward from 05N95W to 07N107W to 06N120W to 06N140W. Scattered moderate convection is from 04N to 09N between 77W and 89W, from 05.5N to 08N between 103W and 108.5W, and from 06N to 08N between 126W and 136W. ...OFFSHORE WATERS WITHIN 250 NM OF MEXICO... Please read the Special Features Section for information on a Gale Warning for the Gulf of Tehuantepec, and on a significant NW swell event forecast to impact the waters offshore Baja California. Aside from the gale warning area, weak surface ridge from high pressure centered N of the region is being disrupted by a modest surface trough extending S along 120W to around 25N. The result is an overall relaxed pressure gradient with light to gentle winds dominating the offshore waters, except for some locally moderate NW winds in the central and southern Gulf of California, due to a low pressure trough along mainland Mexico's west coast. Seas are 4 to 7 ft for offshore waters, locally 8 ft W of Baja California, with 2 to 4 ft seas in the Gulf of California, except in the northern Gulf where seas are less than 2 ft. For the forecast, other than the aforementioned gales in the Tehuantepec region and significant NW swell, light to gentle mainly N winds will increase some this weekend as a NE Pacific high pressure ridge builds toward the region. ...OFFSHORE WATERS WITHIN 250 NM OF CENTRAL AMERICA, COLOMBIA, AND WITHIN 750 NM OF ECUADOR... A surface ridge over the northwestern Caribbean Sea is causing fresh to strong NE gap winds and seas of 4 to 6 ft in the Gulf of Papagayo region. Moderate northerly winds with seas at 3 to 5 ft exist at the Gulf of Panama. S of the monsoon trough, gentle to moderate southerly winds and 4 to 6 ft seas in moderate S to SW swell prevail. For the forecast, high pressure building toward the NW Caribbean will lead to fresh to strong NE gap winds in the Papagayo region into early Tue, before the high weakens and conditions improve. Gales N of the area will induce northerly swell and subsequent rough seas will offshore Guatemala into the weekend. Elsewhere, winds will be moderate or less with moderate seas into early next week. ...REMAINDER OF THE AREA... Please read the Special Features section about very rough seas expected over NW waters through the weekend and into early next week. A weak cold front extends over the far NW waters. Behind the front, fresh to locally strong winds are occurring, with moderate S to SW winds ahead of the front, extending to about 25N and 131W. To the east, a modest surface ridge is inducing light to gentle winds N of 19N, where seas are 5 to 7 ft. S of 19N to the ITCZ, a belt of moderate to locally fresh trades exist, with seas of 6 to 9 ft. S of the ITCZ, 5 to 7 ft seas dominate with gentle to moderate SE winds. For the forecast, see the Special Features section above for details on a broad area of expanding very rough seas. By the start of next week, seas of 8 ft or greater will encompass most waters W of 110W as large to very large NW swell dominates. NE to E tradewinds between the ITCZ and 18N, especially W of 127W, will increase to fresh to locally strong starting Sun. Little change is expected elsewhere. $$ Lewitsky