856 AXPZ20 KNHC 180535 AAB TWDEP Tropical Weather Discussion...Updated NWS National Hurricane Center Miami FL 0535 UTC Mon Mar 18 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 0000 UTC surface analysis and satellite imagery through 0300 UTC. ...SPECIAL FEATURE... Gulf of Tehuantepec Gale Warning: High pressure will build behind a cold front moving through the Gulf of Mexico early this week. This pattern, along with local drainage flow effects, will support gap winds to minimal gale force across the Gulf of Tehuantepec late Tue evening into early Wed morning. Expect sustained winds to briefly reach 35 kt during this time, with seas building as high as 10 ft downstream across the Gulf of Tehuantepec early Tue through Wed. ...INTERTROPICAL CONVERGENCE ZONE/MONSOON TROUGH... A surface trough extends from 08N78W to 05N95W. The ITCZ continues from 05N95W to 04N120W to 05N130W to 04N140W. Scattered moderate convection is noted within 180 nm south of the trough between 85W and 95W, and within 120 nm north of the ITCZ between 100W and 105W. Scattered moderate to isolated strong convection is evident from 05N to 10N between 115W and 120W. ...OFFSHORE WATERS WITHIN 250 NM OF MEXICO... Please see the Special Features section for information about a gale warning for the Gulf of Tehuantepec. A surface ridge extends from 1018 mb high pressure centered near 31N123W southeastward to 15N105W. An earlier scatterometer satellite pass confirmed fresh NW winds across the central and southern Gulf of California, funneling between this high pressure and lower pressure over central Mexico. Elsewhere, this pattern is maintaining gentle to moderate breezes across the offshore waters of Mexico. A recent altimeter satellite pass indicated slight to moderate combined seas prevail everywhere. For the forecast, expect moderate to fresh NW winds from the central Gulf of California to Cabo Corrientes to persist through Tue as the high pressure builds west of the region and low pressure deepens over central Mexico. These winds will diminish through late Tue. Farther south, expect strong to near-gale gap winds starting late Mon over the Gulf of Tehuantepec. These winds will reach minimal gale force late Tue into Wed, associated with high pressure north of the area following a cold front moving into southern Mexico. These gap winds and associated rough seas will diminish across the Gulf of Tehuantepec by late Wed. ...OFFSHORE WATERS WITHIN 250 NM OF CENTRAL AMERICA, COLOMBIA, AND WITHIN 750 NM OF ECUADOR Fresh gap winds persist across the Gulf of Papagayo, a combination of local drainage effects and a relatively tight gradient related to high pressure north of the area. Seas are 3 to 5 ft north of 05N, and 5 to 7 ft primarily in southerly swell. A recent altimeter pass indicated seas to 8 ft persist close to the south of the offshore waters around the Galapagos in the southern swell. For the forecast, high pressure north of the area will continue to support pulses of fresh northeast to east winds in the Papagayo region into early Tue, then possibly returning Wed. Light to gentle winds and moderate seas will continue elsewhere through the forecast period. Farther south, southerly swell reaching 8 ft will persist through late Mon from offshore Ecuador to the Galapagos Islands. ...REMAINDER OF THE AREA... A 1011 mb low pressure remains mostly stationary near 23N140W. A few showers and thunderstorms are evident with in 90 nm to the southeast of the low center. This low is associated with a broad, negatively tilted mid to upper level trough reaching from northwest of the region to roughly over 15N115W, where related divergent flow aloft is supporting a small cluster of showers and thunderstorms. Broad surface ridging is in place north of 25N, supporting mostly gentle breezes across the region, except for moderate trade wind flow over tropical waters from 08N to 15N. NW swell of 6 to 7 ft covers most of the region west of 105W, with seas to 9 ft in the area of moderate trade winds, near the low at 23N140W, and farther south of the equator where a component of SE swell is adding to the mix. Combined seas of 5 to 7 ft in mixed NW and S swell are evident east of 105W. For the forecast, low pressure W of the area along the surface trough will move E through Mon, with winds increasing to fresh along 140W and north of 27N. The low may linger through the early part of the week before weakening and opening to a trough. The NW swell to 8 ft will persist north of 10N and west of 130W tonight, gradually decaying thereafter except mixing with moderate trade from 05N to 15N west of 110W to maintain combined seas in excess of 8 ft Mon and Tue. $$ Christensen