000 AXPZ20 KNHC 192120 TWDEP Tropical Weather Discussion NWS National Hurricane Center Miami FL 2205 UTC Sat Oct 19 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 1800 UTC surface analysis and satellite imagery through 2100 UTC. ...SPECIAL FEATURES... Gulf of Tehuantepec Gale Warning: A ridge across the eastern slopes of the Sierra Madre Mountains in Mexico will continue to support gale force winds in the 30 to 40 kt range across the Tehuantepec region through early Sun morning. Seas are forecast to build to 14 or 15 ft tonight within these wind speeds. Seas generated from this gap wind event will spread well away from the Tehuantepec area, with seas 8 ft or greater reaching as far south as 08N on Sun morning. 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. Looking ahead, after tropical cyclone Nadine dissipates over southern Mexico, its remnants are expected to move into the eastern Pacific. The combination of the remnants of Nadine and influences from the Gulf of Tehuantepec gap wind event are forecast to result in the formation of a new low pressure system off the coast of southwestern Mexico in a couple of days. As a result, fresh to strong winds are expected to persist in the Tehuantepec region through at least Tue. ...INTERTROPICAL CONVERGENCE ZONE/MONSOON TROUGH... The monsoon trough extends from 10N86W to 08N100W to a 1012 mb low pressure centered near 14N116W to 11N125W to 12N140W. Clusters of moderate to strong convection are noted over parts of Panama and the Gulf of Panama, mainly N of 06N between 78W and 81W. Scattered moderate convection is noted from 07N to 11N between 100W and 111W, and from 09N to 13N between 115W and 132W. ...OFFSHORE WATERS WITHIN 250 NM OF MEXICO... A Gale Warning remains in effect for the Gulf of Tehunatepec. Please see the Special Features section for more details. A 1027 mb high pressure located N of area near 36N135W extends a ridge across the waters west of Baja California while a frontal boundary is analyzed over the central Gulf of California and a trough extends through central Mexico. The pressure gradient between these features is supporting gentle to moderate NW winds over the waters offshore of Baja California, with moderate NW winds near Cabo San Lucas. Seas are 4 to 7 ft N of Cabo San Lazaro and 3 to 5 ft between Cabo San Lucas and Cabo San Lazaro. Gentle to locally moderate NW winds and seas of 1 to 3 ft are observed in the Gulf of California. Elsewhere away from the gale force winds in the Gulf of Tehuantepec, light to gentle winds and slight to moderate seas in NW swell prevail across the remainder of the Mexican offshore waters. For the forecast, gale force winds are expected in the Gulf of Tehuantepec through early Sun Morning, then fresh to strong winds will persist through at least Tue. Seas are forecast to build to 14 or 15 ft tonight within the strongest winds. Ridging will prevail over the offshore waters while a trough will meander between the Gulf of California and Baja California. This pattern will promote gentle to moderate NW winds across the offshore forecast waters of Baja California, and moderate to fresh NW winds across the central and southern parts of the Gulf of California through Tue. Looking ahead, after tropical cyclone Nadine dissipates over southern Mexico, its remnants are expected to move into the eastern Pacific. The combination of the remnants of Nadine and influences from the Gulf of Tehuantepec gap wind event are forecast to result in the formation of a new low pressure system off the coast of southwestern Mexico in a couple of days. Additional development is expected after that time, and a tropical depression is likely to form during the early to middle part of next week while the system moves westward at about 10 to 15 kt away from the coast of Mexico. This system has a low chance of tropical cyclone development through 48 hours, and a high chance through 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... Once again, scatterometer satellite data show gentle to locally moderate S to SW winds south of the monsoon trough, and light to gentle winds to the north. Seas are generally 3 to 5 ft in the offshore waters of Central and South America, except in the lee of the Galapagos Islands, where wave heights are 1 to 3 ft. For the forecast, gentle to moderate S to SW winds will occur south of the monsoon trough while light to gentle winds will prevail to the north. Seas generated in the Tehuantepec region will propagate across the outer offshore waters of Guatemala and El Salvador through Sun, with seas likely building to 8 to 12 ft. Then, seas are forecast to subside to 5 to 7 ft in this area on Mon. Elsewhere, mainly moderate seas in cross equatorial SW swell are expected, with the highest seas, in the 5 to 7 ft range, between Ecuador and the Galapagos Islands. ...REMAINDER OF THE AREA... High pressure dominates the forecast waters N of 15N and W of 110W producing gentle to moderate winds N of the monsoon trough and W of 120W, and mainly light to gentle winds between 110W and 120W. Seas are generally 5 to 7 ft based on altimeter data, except 8 to 10 ft in NW swell N of 26N between 120W and 126W. Seas of 8 to 10 ft are also noted per altimeter data S of the Equator between 105W and 120W in cross equatorial SW swell. Elsewhere, gentle to moderate winds and moderate seas prevail. For the forecast, the high pressure will move SW and weaken as a cold front approaches from the west. The cold front will approach 30N140W on Mon and become stationary. A low pressure may form along the frontal boundary on Tue, with a cold front reaching the NW corner of the forecast region by Tue night. A swell event is forecast to follow the front. Rough seas north of 26N will slowly subside tonight. $$ GR