000 AXPZ20 KNHC 171549 TWDEP Tropical Weather Discussion NWS National Hurricane Center Miami FL 1605 UTC Sat Feb 17 2024 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 1500 UTC. ...SPECIAL FEATURES... Significant NW Swell Event and Gale Warning: Very large, long-period NW swell generated by a vast gale-force low pressure near 36N147W is causing 12 to 19 ft seas north of 16N and west of 128W. Expect these seas to propagate eastward and stall by Sun morning. Then, a storm-force low pressure currently north of Hawaii is going to track eastward through Tue. Reinforcing NW swell produced by this second low will prolong 12 to 20 ft seas in the same general area through Mon, then create seas of 12 to 13 ft in the Offshore Waters of Baja California Norte Mon evening through Tue night. In addition, a cold front associated with the second low is expected to bring near-gale to gale-force westerly winds north of 28N between 134W and 140W Sat afternoon through evening. Afterward, westerly winds north of 28N between 130W and 140W will stay at strong to near-gale force through Sun night. Gulf of Tehuantepec Gale Warning: A surface ridge building east of the Sierra Madre mountains in Mexico will introduce the next gap wind event in the Tehuantepec region by Sun morning. Winds are forecast to peak at gale to strong-gale force from mid Sun morning through Mon morning. Seas under these winds will range from 10 to 15 ft. Afterward, strong to near-gale gap winds are expected to persist through midweek next week, possibly pulsing to gale-force Mon night through Tue nights. Marine interests in the regions above need to monitor these situations and plan their routes accordingly. Please read the latest High Seas and Offshore Waters Forecasts issued by the National Hurricane Center at website https://www.nhc.noaa.gov/text/MIAHSFAT2.shtml https://www.nhc.noaa.gov/marine/offshores_eastpac.php for more details. ...INTERTROPICAL CONVERGENCE ZONE/MONSOON TROUGH... A surface trough extends from 07N78W to 02N120W. An ITCZ continues from 02N120W to beyond 01N140W. Scattered moderate convection is noted along the surface trough. ...OFFSHORE WATERS WITHIN 250 NM OF MEXICO... Please read the Special Features section above for information about the upcoming Tehuantepec Gale Warning. A tight pressure gradient between a 1022 mb high pressure off Baja California and lower pressure over southern Mexico is sustaining fresh to strong NW to N winds, and 6 to 8 seas off Michoacan and Guerrero States. This same high is also supporting moderate to fresh northerly winds and seas of 2 to 5 ft across the offshore waters of Baja California, central Mexico and the Gulf of California. Mostly gentle winds and seas at 4 to 6 ft in moderate southerly swell prevail for the rest of the southern Mexico offshore waters. Southwesterly flow aloft is streaming thick cirrus over the offshore waters of central and southern Mexico. For the forecast, strong NW to N winds and rough seas will persist offshore of Michoacan and Guerrero States today, then shift to near western Oaxaca State this evening before subsiding late tonight. Gale-force gap winds will begin in the Gulf of Tehuantepec by Sun morning through Mon afternoon. Large, long- period NW swell is forecast to reach the Baja California offshore waters by Sun morning, and near the Revillagigedo Islands on Sun night. It will cause very rough seas in these waters through midweek next week. ...OFFSHORE WATERS WITHIN 250 NM OF CENTRAL AMERICA, COLOMBIA, AND WITHIN 750 NM OF ECUADOR Fresh to strong NE to E gap winds and seas at 5 to 7 ft persist across the Gulf of Papagayo and the coast of Nicaragua. Light to gentle winds with 2 to 4 ft seas are noted at the offshore waters of Costa Rica, western Panama and Colombia. Moderate N winds and seas of 4 to 5 ft are found in the Gulf of Panama. Gentle to moderate southerly winds and 4 to 6 ft seas in moderate S swell prevail at the waters near Ecuador and the Galapagos Islands. Refer to the Monsoon Trough/ITCZ section for convection in the area. For the forecast, fresh to strong easterly gap winds and rough seas will persist in the Papagayo region and off Nicaragua until this afternoon. Elsewhere, relatively benign marine conditions will prevail for the next several days. The next gap wind event along with rough seas are anticipated in the Papagayo region from Mon to beyond midweek next week, as a ridge builds over the northwestern Caribbean. Fresh to strong NE to E gap winds could reach gale-force Wed night into early Thu morning. Looking ahead, fresh N winds and building seas are expected over the Gulf of Panama by late Mon. ...REMAINDER OF THE AREA... Please read the Special Features section above for information about the ongoing Significant Swell event, and an upcoming Gale Warning. A cold front curves southwestward from off the southern California coast across 30N131W to 24N138W. Scattered showers are occurring near and up to 150 nm northwest of this boundary. Fresh to strong SW winds and seas at 8 to 12 ft exist up to 120 nm southeast of the cold front between 23N and 30N. Gentle to fresh NW winds are noted behind the front, seas in this area are mentioned in the Special Features section above. A 1021 mb high near 26N123W is promoting light to gentle winds and 4 to 7 ft seas north of 20N between 115W-135W. Farther south, gradient between this high and the ITCZ/surface trough is prolonging moderate to fresh NE to ENE winds and seas of 6 to 8 ft from 04N to 15N west of 118W, and from 08N to 17N between 108W and 118W. From 03N to 03S between 91W and 120W, gentle to moderate S winds and 5 to 7 ft seas exist. Light to gentle winds with 4 to 7 seas in mixed moderate swell prevail for the rest of the waters. For the forecast, the high pressure will gradually drift southward and weaken through the weekend, which should allow winds north of the ITCZ/trough to subside Mon and Tue. The aforementioned cold front is forecast to reach from 30N124W to 20N140W tonight while weakening. A second stronger cold front will enter the northwest corner of the discussion area this evening, then merge with the first cold front on Sun. High pressure building southeastward behind the merged front will cause winds and seas north of the ITCZ to increase again by midweek next week. $$ ERA