000 AXPZ20 KNHC 201602 TWDEP Tropical Weather Discussion NWS National Hurricane Center Miami FL 1605 UTC Sun Oct 20 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... Gulf of Tehuantepec Gale Warning: Minimal gale force winds of 30 to 35 kt are expected in the Tehuantepec region this morning, then winds will diminish below gale force early this afternoon. Seas of 9 to 12 are still expected with the strongest winds, and will gradually subside to 6 to 9 ft by tonight. Seas generated from this gap wind event continue to spread well away from the Tehuantepec area, with seas 8 ft or greater reaching as far south as 09N today. Marine interests transiting across the Gulf of Tehuantepec this weekend should be aware of this gap wind event, and take the necessary action to avoid hazardous marine conditions over the affected waters. ...INTERTROPICAL CONVERGENCE ZONE/MONSOON TROUGH... The monsoon trough extends from 10N86W to a 1011 mb low pressure centered near 08N105W to a 1011 mb low near 12N116W to beyond 11N140W. Clusters of moderate to isolated strong convection are noted in the Tehuantepec region from 11N to 15N between 92W and 98W. Scattered moderate to isolated strong convection is ongoing from 06N to 12N between 102W and 110W, and from 08N to 12N between 114W and 125W. ...OFFSHORE WATERS WITHIN 250 NM OF MEXICO... A Gale Warning remains in effect for the Gulf of Tehunatepec this morning. Please see the Special Features section for more details. A weak ridge dominates the offshore forecast waters of Baja California and supports gentle to moderate NW winds with seas of 3 to 5 ft. In the Gulf of California, moderate to locally fresh NW winds are observed across the central and southern parts of the Gulf where seas are in the 2 to 4 ft range. Gentle to moderate NW winds and seas of 1 to 2 ft prevail in the northern part of the Gulf. Latest scatterometer satellite data show moderate NW winds occurring offshore of Jalisco through Guerrero where seas are 3 to 5 ft. For the forecast, minimal gale force winds in the Tehuantepec area will diminish below gale force early this afternoon. Seas will gradually subside to 6 to 9 ft by tonight. Ridging will prevail over the offshore waters while a trough meanders between the Gulf of California and Baja California, and strong high pressure becomes established over central Mexico. This pattern will support fresh to strong NW to N winds over central and southern portions of the Gulf of California through midweek, Looking ahead, the combination of the remnants of Nadine and influences from a Gulf of Tehuantepec gap wind event are forecast to result in the formation of a new low pressure system off the coast of southern Mexico in a day or so. Additional development is expected after that time, and a tropical depression is expected to form during the early to middle part of this week while the system moves westward at about 15 mph away from the coast of Mexico. There is a medium chance of tropical formation within the next 48 hours, and a high chance of formation over the next 7 days. Please, read the latest NHC Tropical Weather Outlook at www.hurricanes.gov for more details. ...OFFSHORE WATERS WITHIN 250 NM OF CENTRAL AMERICA, COLOMBIA, AND WITHIN 750 NM OF ECUADOR... Latest scatterometer satellite data show moderate S to SW winds occurring south of the monsoon trough, and light to gentle winds to the north. Altimeter satellite data depict seas of 5 to 7 ft south of the trough, especially offshore of Colombia and Ecuador, where a long-period southern hemisphere swell is propagating northward through the region. Seas of 6 to 9 ft, generated by the N gap winds in the Gulf of Tehuantepec, are occurring well offshore of Guatemala. Scattered moderate to strong convection along the periphery of Tropical Depression Nadine is ongoing offshore of Guatemala and El Salvador. Gusty winds and rough seas are likely near convection. For the forecast, cross equatorial long-period S swell will propagate northward today, creating moderate to locally rough seas across most of the offshore waters of Central and South America. The highest seas, in the 6 to 8 ft range, are expected offshore of Ecuador. Rough seas generated in the Tehuantepec region will propagate across the outer offshore waters of Guatemala and El Salvador today, with seas slowly subsiding Mon into Tue. Otherwise, gentle to moderate S to SW winds will prevail south of the monsoon trough, with light to gentle winds occurring farther north. ...REMAINDER OF THE AREA... A 1022 mb high, centered to the north of the forecast waters near 32N135W, dominates the forecast waters north of the monsoon trough. Latest scatterometer satellite data show generally moderate NE winds in this region, with locally fresh breezes occurring south of 24N and west of 128W. Moderate seas in N to NE swell prevail in the aforementioned area. A trough is analyzed to the north of a 1012 mb low centered near 12N117W, with satellite data showing locally fresh NE winds and locally rough seas from 13N to 17N between 114W and 120W. A long-period cross equatorial swell is leading to seas of 8 to 10 ft south of 05N and east of 125W, as noted from altimeter satellite data. Elsewhere, gentle to moderate S to SE winds prevail south of the monsoon trough. For the forecast, the cross equatorial S swell will lead to rough seas south of 08N through Mon before seas slowly subside by midweek. The high pressure centered to the north of the forecast waters will weaken as a cold front approaches from the northwest in the coming days. A low pressure may form along the frontal boundary on Tue, with a cold front reaching the NW corner of the forecast region Tue night. Building NW swell behind the front will lead to rough seas north of 25N and west of 130W late this week. $$ GR