000 AXPZ20 KNHC 171554 TWDEP Tropical Weather Discussion NWS National Hurricane Center Miami FL 1605 UTC Mon Apr 17 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: A cold front is moving across the Gulf of Mexico and southern Mexico currently, followed by high pressure and a cool, relatively dense airmass. This pattern is supporting gap winds to minimal gale force across the Gulf of Tehuantepec. Combined seas are reaching as high as 11 ft downstream. Winds will diminish later this afternoon as airmass supporting the gap winds modifies and the high pressure shifts eastward. Combined seas will subside afterward through the later afternoon and early evening. Please refer to latest High Seas Forecast issued by National Hurricane Center at website: https://www.nhc.noaa.gov/text/MIAHSFEP2.shtml for more details. ...INTERTROPICAL CONVERGENCE ZONE/MONSOON TROUGH... A surface trough extends from 08N78W to 06N95W. The ITCZ continues from 06N95W to beyond 04N140W. Another trough is farther south, extending from 02N85W to 01S95W. A second ITCZ continues from 01S95W to 02S120W. Scattered moderate convection is ongoing from 06N to 09N between 81W and 88W, and from 05N to 10N between 116W and 121W. ...OFFSHORE WATERS WITHIN 250 NM OF MEXICO... Please refer to the Special Features section above for details on an upcoming Gulf of Tehuantepec gap wind gale-force event. A broad surface ridge extends from high pressure 1030 mb high pressure centered near 35N150W southeastward toward the Revillagigedo Islands. Ship observations indicate moderate to fresh NW winds winds with 5 to 7 ft combined seas off Baja California, between the ridge and lower pressure over north- central Mexico. Gentle to moderate winds persist elsewhere off Mexico, except for the gale event over the Gulf of Tehuantepec. Combined seas are 4 to 6 ft elsewhere in open waters. For the forecast, the high pressure over the eastern Pacific will support fresh to occasionally strong NW winds off Baja California north of Cabo San Lazaro through late Thu, with combined seas reaching as 10 ft due in part to NW swell. ...OFFSHORE WATERS WITHIN 250 NM OF CENTRAL AMERICA, COLOMBIA, AND WITHIN 750 NM OF ECUADOR... Moderate to fresh east winds prevail across the waters of the Gulf of Papagayo region, with these winds are 4-6 ft. Moderate N to NE winds are over the Gulf of Panama, where seas are 3 ft. Elsewhere, light to gentle variable winds and slight seas prevail. For the forecast, high pressure north of the area will support fresh to occasionally strong gap winds pulses through mid week across the Gulf of Papagayo and the coast of Nicaragua. Moderate winds in the Gulf of Panama will briefly pulse to fresh Tue and Wed nights. Elsewhere, light to gentle variable winds and moderate seas in SW swell will prevail. ...REMAINDER OF THE AREA... Buoy observations and earlier scatterometer satellite passes confirm fresh to strong trade winds from 05N to 15N west of 125W, between a trough in the deep tropics near 120W and the subtropical ridge north of 20N. Combined seas in this area are 7 to 9 ft, with a component of NW swell. Scattered thunderstorms are active near the surface trough, which extends from 04N to 10N along 120W. Gentle to moderate winds and moderate combined seas are noted elsewhere. For the forecast, high pressure will dominate the northern forecast waters over the next several days, strengthening modestly Tue through Wed. The associated pressure gradient will support moderate to fresh trade winds over the west-central waters. An elongated zone of seas 8 to 9 ft in mixed N and E swell exists W of 114W from about 06N to 15N. NE trade winds within this area will increase to fresh to strong starting tonight and into early Mon as the high pressure ridge strengthens some. By Mon afternoon the high pressure ridge will weaken some allowing for these winds to diminish back to fresh speeds. Seas will subside slightly to 8-9 ft in N to NE swell, and continue to further subside through Tue as the N to NE swell over this area decays. A weakening cold front will push southward across the far northern waters Tue and Tue night. New NW swell will follow the front reaching south of 30N and to near 26N by late Tue night. Seas of 8-9 ft are expected with this NW swell. The swell will propagate farther S into Thu, then begin to subside to 8 ft later on Thu. $$ Christensen