000 AXPZ20 KNHC 222120 TWDEP Tropical Weather Discussion NWS National Hurricane Center Miami FL 2205 UTC Wed Sep 22 2021 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... A Gale Warning remains in effect for the Gulf of Tehuantepec tonight into Thu morning. High pressure building across the eastern slopes of the Sierra Madre Mountains, in the wake of an early cold front, currently moving across the Gulf of Mexico, will support the first gap wind event in the Tehuantepec region this season. Winds are forecast to reach minimal gale force tonight into Thu morning. Seas are expected to build to 9-11 ft with this event. Winds are forecast to diminish below gale force by early Thu afternoon but the gap wind event will continue through Sat. Please, refer to 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. ...TROPICAL WAVES... The axis of a tropical wave is along 111W and from 06N to 18N, moving west at 10 to 15 kt. Scattered moderate convection is noted where the wave meets the monsoon trough. The axis of a tropical wave is along 121W from 06N to 20N, moving west at 10 to 15 kt. A 1010 mb low pressure is along the wave axis near 15N121W. Scattered moderate convection is noted within about 120 nm NW quadrant of center. Development of this system during the next day or two, if any, is likely to be slow. After that time, this system is forecast to move into an environment of stable air and strong upper-level winds, which should inhibit further development. The latest Tropical Weather Outlook gives this system a low chance of tropical cyclone formation through 48 hours, and also through 5 days. Please, refer to the latest Tropical Weather Outlook, at www.hurricanes.gov for more details. The tropical wave previously located along 140W has moved W of area. Scattered moderate to isolated strong convection is still noted from 08N to 11N W of 138W. ...INTERTROPICAL CONVERGENCE ZONE/MONSOON TROUGH... The monsoon trough extends from 09N84W to 10N100W to 12N117W. The ITCZ begins near 12N124W and continues to beyond 09N140W. Scattered moderate to isolated strong convection can be found N of 05N E of 80W to the coast of Colombia, including the Gulf of Panama, from 10N to 13N between 98W and 105W, within 120 nm NW quadrant of low pressure located near 15N121W, and from 08N to 11N W of 138W. OFFSHORE WATERS WITHIN 250 NM OF MEXICO... A ridge continues to dominate the offshore forecast waters of Baja California producing gentle to moderate NW to N winds. Seas are 4 to 6 ft N of Cabo San Lazaro, and 3 to 5 ft elsewhere. A recent scatterometer pass provided observations of 20 to 30 kt northerly winds in the Tehuantepec region and downwind to near 14N95W. Gentle to moderate northerly winds prevail in the Gulf of California. For the forecast, please, see the Special Features section for more details on the first Tehuantepec wind event of the season. Surface ridging will continue to dominate the offshore forecast waters of Baja California supporting mainly gentle to moderate NW to N winds through Sun. Light to gentle winds will prevail over the SW Mexico offshore waters. Gentle to moderate winds are expected in the northern Gulf of California through Fri, and in the central and south parts of the Gulf through tonight. After that, mainly light and variable winds are expected across the entire Gulf. OFFSHORE WATERS WITHIN 250 NM OF CENTRAL AMERICA, COLOMBIA, and WITHIN 750 NM OF ECUADOR... Gentle to moderate southerly winds will prevail across the offshore waters of Costa Rica, Panama, Colombia and Ecuador through Thu, then mainly light to gentle winds will prevail. Mainly light and variable winds are forecast across the offshore waters from Guatemala to northern Costa Rica through Sat. Cross equatorial SW swell will reach again the forecast area toward the end of the week, building seas to 6-7 ft between Ecuador and the Galapagos Islands during the upcoming weekend. REMAINDER OF THE AREA... The northern forecast waters remain under the influence of a surface ridge anchored on a 1027 mb high pressure located near 36N138W. The pressure gradient between the ridge and a low pres center near 15N121W supports an area of moderate to locally fresh NE winds roughly from 16N to 24N between 120W and 132W. Satellite derived wind data confirmed the presence of these winds. Seas are 6-8 ft within these winds based on altimeter data. Winds across this area will diminish over the weekend. $$ GR