000 AXPZ20 KNHC 161554 TWDEP Tropical Weather Discussion NWS National Hurricane Center Miami FL 1605 UTC Sat Dec 16 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... Gulf of Tehuantepec Gale Warning: Strong to near gale force north to northeast winds are presently in the Gulf of Tehuantepec region and well to the southwest of the Gulf to near 11N98W. Seas are 8-10 ft within these winds. The gradient associated to developing low pressure area over the Gulf of Mexico will bring fresh to strong northerly winds over the western part of the Gulf. These winds will support the return of gale-force winds in the Gulf of Tehuantepec by this afternoon. Northerly winds are forecast to increase to 30-35 kt with seas building to the range of 9-13 ft tonight into Sun morning. This gap wind event will continue well into next week, pulsing through mid week. Rough to very rough seas are expected. NW Eastern Pacific Gale Warning: A deep extratropical low pressure system is located north of the area near 34N139W. A cold front extends from 30N127W to 20N132W then becomes stationary to 13N140W. Gale force winds are expected to develop in the vicinity of the cold front this afternoon and continue following the front through tonight. An extensive set of northwest swell will follow the front over the NW section of the area and spread across most of our forecast waters through Tue. The 12-19 ft seas will even grow larger, to the range of 16-22 ft, from this afternoon through tonight before they begin to slowly subside into early next week. Before they subside, they are likely to lead to hazardous marine conditions. The leading edge of the 12 ft and greater seas will reach as far south as 18N and west of about 127W by Sun afternoon. 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 10N86W to 05N105W. The ITCZ continues from 05N105W to 08N140W. Scattered moderate convection is within 120 nm either side the of the boundaries and E of 112W. ...OFFSHORE WATERS WITHIN 250 NM OF MEXICO... Please refer to the Special Features section for details on an ongoing Gulf of Tehuantepec Gale Warning. The combination of high pressure over the U.S. Great Basin and relatively lower pressure over northwest Mexico and the Gulf of California area is allowing for fresh to strong northwest to north winds over the entire Gulf of California with seas to 6 ft. These winds are spilling out of the Gulf reaching as far south as the waters between Cabo Corriente and 109W. Meanwhile, weak pressure gradient dominates the Mexican offshore waters, outside of the Gulf of Tehuantepec. Moderate or weaker winds and slight to moderate seas continue across the rest of the offshore waters. Seas across the Baja California offshore waters and over the southern Mexico offshore waters are in the 4-6 ft range due to long-period west to northwest swell. No significant convection is presently noted over these waters. For the forecast, the ongoing gap wind event in the Gulf of Tehuantepec region is forecast to persist well into next week. Strong to near gale force northerly gap winds will continue this morning, then increase to gale force in the afternoon. These winds are forecast to remain at gale force into the middle of next week. Rough to very rough seas can be expected with these winds. Meanwhile, high pressure will build over the Great Basin in the western United States today. The associated gradient will maintain fresh northwest winds over the Gulf of California through early this afternoon, then diminish to moderate speeds through Sun and to gentle speeds Mon. Seas to around 8 ft associated with a large swell event will reach the outer offshore forecast waters of Baja California between Cabo San Lazaro and Punta Eugenia by Sun night. ...OFFSHORE WATERS WITHIN 250 NM OF CENTRAL AMERICA, COLOMBIA, AND WITHIN 750 NM OF ECUADOR... Moderate northeast to east winds are in the Gulf of Papagayo region, including the coast of southern Nicaragua. Seas with these winds are in the range of 3-5 ft. To the northwest of the Gulf of Papagayo region, seas of 5-8 ft in a northwest swell generated by the Gulf of Tehuantepec gap wind event are over the outer offshore waters of Guatemala and El Salvador. Gentle north winds and seas of 3-4 ft are in the Gulf of Panama. Scattered showers and a few thunderstorms are along and just inland the coast of Colombia from 01N to 05N. For the forecast, the moderate northeast to east winds in the Gulf of Papagayo will increase back to fresh to strong beginning Sun night, and continue through the middle of next week while expanding to the southwest. These winds are expected to reach near gale force Tue night and Wed. Rough seas are expected over the Guatemala and El Salvador offshore waters Sun and Sun night due to another Gulf of Tehuantepec gap wind event that begins on Sat. Elsewhere, winds are moderate or weaker for the next several days. ...REMAINDER OF THE AREA... A deep extratropical low pressure system is located north of the area near 34N139W. It is forecast to meander N of the area through Sun night. A tight pressure gradient associated with this low pressure system will remain in place over the northwest corner of the forecast area through early Sun. A cold front extends from 30N12W to 20N132W, then becomes stationary to 13N140W. Near-gale southwest winds are currently ahead of the front to near 125W and north of 25N along with seas of 8-12 ft in a west to northwest swell. Strong west to northwest winds are west of the front north of 24N with seas of 13-19 ft in a west to northwest swell. Refer to the section above for more details about the Gale Warning in effect for this area. Elsewhere, a N to S high pressure ridge offshore southern California and northern Baja California controls the gradient across the remainder of the forecast waters north of the ITCZ and west of 110W. Gentle to moderate winds are on either side of the ITCZ/Monsoon trough with seas of 5-7 ft in mixed swell. For the forecast, gale force winds will develop in the vicinity of the frontal boundary across the NW portion of the basin this afternoon and continue through tonight. The trade winds north of the ITCZ to near 13N will increase slightly to fresh speeds through Sun. Winds south of the ITCZ will be in the moderate to fresh range through Mon. Fresh to strong winds from the gap wind event of Tehuantepec will merge into the trade winds between 100W-104W by late Sun. Swell from the Tehuantepec gap wind event will spread southwest and west reaching to near 104W by late Sun, with generated seas of 8-9 ft. $$ ERA