000 AXPZ20 KNHC 282120 TWDEP Tropical Weather Discussion NWS National Hurricane Center Miami FL 2205 UTC Fri Apr 28 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 1800 UTC surface analysis and satellite imagery through 2100 UTC. ...SPECIAL FEATURES... Gale Warning in the Gulf of Tehunatepec: A brief gap wind event is expected in the Tehuantepec region Sat night into Sun as a ridge builds across the eastern slopes of the Sierra Madre Mountains in Mexico behind a cold front moving through the Gulf of Mexico. Winds are forecast to suddenly increase to 30 to 35 kt on Sat night, with seas building to 12 or 13 ft by early Sun morning. Fresh to strong northerly winds will persist on Sun afternoon, with seas in the 8 to 11 ft range. Winds will further diminish to 20 kt by Sun evening. At this time, seas of 8 to 9 ft in northerly swell generated by this gap event are forecast to dominate the waters from 11N to 14N between 95W and 97W. 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. Climatologically, the first gale-force event of the season occurs in mid-October, with the final gale-force event occurring in lat March or early April. Occasionally, gale-force events may occur as early as September, and as late as May. ...INTERTROPICAL CONVERGENCE ZONE/MONSOON TROUGH... The monsoon trough extends from northern Colombia near 10N75W to 07N90W to 06N108W. The ITCZ continues from 06N108W to 05N125W to beyond 03N140W. Scattered moderate to isolated strong convection is observed from 01N to 05N between 80W and 85W. Scattered moderate to isolated strong convection is also noted from 01N to 04N between 82W and 86W, from 02N to 07N between 86W and 100W and from 05N to 11N between 100W and 122W. ...OFFSHORE WATERS WITHIN 250 NM OF MEXICO... A Gale Warning is in effect for the Gulf of Tehuantepec. Please, see the Special Features section for details. A weak ridge extends from 1021 mb high pressure located near 27N134W southeastward toward the Revillagigedo Islands. This pattern is supporting gentle to moderate NW to N winds across the offshore waters of Baja California. Wave heights are 4 to 6 ft in open waters, with moderate S to SW swell. Light and variable winds are noted per scatterometer data in the Gulf of California where seas are in the 1 to 3 ft range, highest near the entrance to the Gulf. Light W to NW winds dominate the remainder of the Mexican offshore waters, with seas generally in the 4 to 5 ft range in S to SW swell. Areas of smoke from agricultural fires are still noted on visible satellite imagery off southern Mexico. For the forecast, the relatively weak pressure pattern will continue to support gentle to moderate NW winds across the Mexican offshore waters through early Sun. High pressure building across the eastern slopes of the Sierra Madre Mountains in Mexico behind a cold front moving through the Gulf of Mexico will support strong to minimal gale force northerly winds and building seas across the Gulf of Tehuantepec Sat night through Sun night. A NW swell event will propagate across the waters north of Punta Eugenia late Sun night into Mon with building seas of 8 to 10 ft late on Mon. Expect increasing S to SW winds and building seas in the northern Gulf of California Sun night through Tue night ahead of a frontal trough. ...OFFSHORE WATERS WITHIN 250 NM OF CENTRAL AMERICA, COLOMBIA, AND WITHIN 750 NM OF ECUADOR... Light to gentle winds and slight to moderate combined seas in SW swell dominate the forecast area, with the exception of gentle to moderate northerly winds across the Gulf of Panama and downstream to near 06N80W based on recent satellite derived wind data. For the forecast, a weak pressure gradient will support light to gentle winds across the region through the upcoming weekend. Expect slight to moderate combined seas primarily in S to SW swell. Also, areas of smoke from agricultural fires may persist over the offshore waters from northern Costa Rica to Guatemala. ...REMAINDER OF THE AREA... A weak surface ridge, anchored by 1021 mb high pressure situated near 27N134W, dominates the northern forecast waters, mainly N of 15N and W of 110W. Moderate trades are noted along the southern periphery of the ridge. Mainly gentle winds are evident over the remainder of the area. Combined seas are generally 4 to 6 ft in mixed NW and SW swell. Scatterometer data indicate stronger winds associated with the convection along the monsoon trough/ITCZ. For the forecast, the ridge will continue to dominate the northern forecast waters north of 20N through Sat, maintaining moderate trade winds farther south. High pressure will strenghten N of the area on Sun bringing moderate to fresh trades mainly N of the ITCZ and W of 130W, and producing fresh to locally strong N to NE winds to the north of 25N by late Sun, and north of 20N by late Mon. In addition, a weak cold front will move across the NE waters Sun through Mon while dissipating. Then, high pressure will remain in control of the weather pattern across the northern forecast region through early next week. $$ GR