000 AXPZ20 KNHC 210913 TWDEP Tropical Weather Discussion NWS National Hurricane Center Miami FL 1005 UTC Sun Mar 21 2021 Tropical Weather Discussion for the eastern Pacific Ocean from the Equator to 32N, east of 140W. The following information is based on satellite imagery, weather observations, radar, and meteorological analysis. Based on 0600 UTC surface analysis and satellite imagery through 0900 UTC. ...SPECIAL FEATURES... Gulf of Tehuantepec Gale Warning: A ridge across the eastern slopes of the Sierra Madre mountains in Mexico supports gale force winds across the Tehuantepec region. A recent scatterometer pass provided observations of minimal gale force winds across the Tehuantepec area and downwind to near 14.5N95W. Winds are forecast to diminish below gale force by late this morning. Then, fresh to strong northerly winds are expected to persist through Mon morning. Seas will gradually subside across the area through Mon. Please read the latest NWS High Seas Forecast from the National Hurricane Center at the website: www.nhc.noaa.gov/text/MIAHSFEP2.shtml for more details. Of note, the average date of the last Tehuantepec gale event is around April 9th. A couple of Tehuantepec gale events were detected in May based on the last 20 years of records. Within this period, an average of 16 gale and 5 storm events is noted per cold season. ...INTERTROPICAL CONVERGENCE ZONE/MONSOON TROUGH... A surface trough extends from a 1009 mb low pressure located over northern Colombia near 10N74W to 04N90W. The ITCZ continues from 04N90W to 02N120W to 03N140W. Scattered moderate convection is from 03N to 05N between 95W and 99W, and from 01N to 05N between 117W and 130W. As it is normal for this time of the year, a second ITCZ is south of the equator and extends from 02S90W to 01S100W to 02S115W. OFFSHORE WATERS WITHIN 250 NM OF MEXICO... A Gale Warning remains in effect for the Gulf of Tehuantepec. Please see the Special Features section above for details. High pressure dominates the offshore forecast waters of Baja California. The pressure gradient between this system and lower pressures over the SW CONUS is resulting in fresh to strong NW winds across the waters N of Punta Eugenia. As high pressure continues to strengthen, these winds will spread SE reaching the waters N of Cabo San Lazaro by this evening. Seas 8 to 11 ft in NW swell currently dominate the waters N of Cabo San Lazaro. This swell event will continue to propagate southward reaching the Revillagigedo Islands by this evening. Gentle to moderate winds are expected in the northern Gulf of California through Tue night, while moderate to locally fresh northerly winds are forecast elsewhere across the Gulf but mainly across the central part. Strong to gale force westerly winds are expected over northern Mexico and E of the Sierra Madre Occidental on Mon, with fresh to strong W to NW winds by Mon night. These winds blow between canyons over a higher terrain and then intensify. The mountain effect is amplified. OFFSHORE WATERS WITHIN 250 NM OF CENTRAL AMERICA, COLOMBIA, and WITHIN 750 NM OF ECUADOR... Fresh to strong winds are expected in the Gulf of Papagayo and downwind to about 90W through Mon night. Seas will build to 8-10 ft. Fresh N winds are expected in the Gulf of Panama at night through Mon night. Large seas from a Tehuantepec gap wind event will spread into the offshore waters of Guatemala and El Salvador through tonight. Light to gentle winds will prevail elsewhere. Long period S to SW swell will maintain seas in the 4 to 6 ft range across the waters between Ecuador and the Galapagos Islands over the next several days. REMAINDER OF THE AREA... A strong high pressure system will remain N of 30N over the next couple of days with a ridge over the northern forecast waters. The pressure gradient between the ridge and lower pressures in the vicinity of the ITCZ will support a large area of fresh to strong NE winds covering the waters from 10N to 28N W of 130W and from 16N to 26N between 120W and 130W by tonight, and from 14N to 28N W of 127W by Mon night. The aerial extent of these winds will diminish on Tue as high pressure located N of the area weakens some. Long period NW swell is propagating across the forecast waters W of 115W, and will mix with cross equatorial SW swell over the next couple of days. As a result, seas of 8 ft or greater will dominate most of the waters N of 02N and W of 115W by this morning, and N of 02N W of 110W by Mon morning. Seas of 8-9 ft are also expected S of the equator in SW swell. $$ GR