000 AXPZ20 KNHC 182134 TWDEP Tropical Weather Discussion NWS National Hurricane Center Miami FL 2205 UTC Fri Oct 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 1800 UTC surface analysis and satellite imagery through 2100 UTC. ...SPECIAL FEATURES... Gulf of Tehuantepec Gale Warning: Fresh to strong northerly winds are blowing across the Gulf of Tehuantepec and downwind to about 13N as high pressure surges southward along the eastern slopes of the Sierra Madre Mountains in Mexico in the wake of a stationary front that extends across the Bay of Campeche. Winds are forecast to increase to gale-force speeds by this evening. Expect N to NE winds in the 30 to 40 kt range, and building seas up to 12 ft with this gap wind event. Seas generated from this event will spread well away from the Tehuantepec area, with seas 8 ft or greater reaching as far south as 08N on Sun. 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. Climatologically, the first gale-force event of the season occurs in mid-October, with the final gale-force event occurring in late March or early April. Occasionally, gale-force events may occur as early as September, and as late as May. ...INTERTROPICAL CONVERGENCE ZONE/MONSOON TROUGH... The monsoon trough extends from 10N85W to 07N100W to 1010 mb low pressure located near 13N112W to another 1012 mb low pressure situated near 13N129W to 11N134W. The ITCZ continues from 11N134W to beyond 11N140W. Scattered moderate to isolated strong convection is noted from 08N to 14N between 105W and 120W. ...OFFSHORE WATERS WITHIN 250 NM OF MEXICO... A Gale Warning is in effect for the Gulf of Tehunatepec. Please see the Special Features section for more details. A ridge dominates the offshore forecast waters of Baja California supporting gentle to moderate NW winds N of Cabo San Lazaro. Seas are 6 to 8 ft N of Punta Eugenia, and 4 to 6 ft between Punta Eugenia and Cabo San Lazaro. Moderate to locally fresh NW winds are noted, per scatterometer data, between Cabo San Lucas and Cabo San Lazaro where seas are in the 4 to 6 ft range. A cold front has reached the north part of the Gulf of California. Fresh to strong NW winds and seas of 4 to 7 ft follow the front while moderate to fresh SW to W are observed ahead of the front roughly from 28N to 30N with seas of 2 to 4 ft. Aside from the fresh to strong northerly winds in the Gulf of Tehuantepec, light to gentle winds and seas of 4 to 6 ft prevail across the remainder of the Mexican offshore waters. For the forecast, gale force winds are expected to persist in the Tehuantepec region beginning this evening through early Sun morning. A ridge will remain in control of the weather pattern across the offshore forecast waters on Baja California through at least Sun, producing gentle to moderate NW winds and moderate seas. Winds in the northern Gulf of California will diminish to 2O kt or less by tonight. Looking ahead, an area of low pressure is expected to form in a few days well offshore of southwestern Mexico. Gradual development is possible thereafter, and a tropical depression could form around the middle of next week as the system moves westward at 10 to 15 kt. This system has a medium chance of tropical cyclone development through 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... Light to gentle SW to W winds prevail north of the monsoon trough, and gentle to locally moderate S to SW winds are occurring south of the trough. Seas of 3 to 5 ft are noted 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 locally moderate S to SW winds will occur south of the monsoon trough while light to gentle winds will prevail north of it this upcoming weekend. Cross equatorial SW swell will continue to propagate across the offshore forecast waters, building seas to 5 to 7 ft between Ecuador and the Galapagos Islands late on Sun. Seas generated in the Tehuantepec region will propagate across the outer offshore waters of Guatemala and El Salvador through Sun with building seas of 6 to 9 ft. ...REMAINDER OF THE AREA... High pressure of 1029 mb located N of area near 37N132W extends a ridge across the northern forecast waters, particularly N of 20N and W of 115W. The pressure gradient between the high pressure center and a dissipating frontal boundary located along 25N/26N is producing an area of fresh to strong N to NE winds N of 26N between 125W and 130W with seas of 8 to 9 ft. Similar wave heights in NW swell are also noted N of 29N between 119W and 125W. Elsewhere, gentle to moderate winds and moderate seas prevail, with an area of rough seas from 09N to 15N W of 130W where a couple of altimeter passes indicate seas of 8 to 10 ft in mixed NE and NW swell. For the forecast, high pressure will continue to dominate the north waters through early next week supporting mainly a gentle to moderate anticyclonic flow N of the ITCZ/Monsoon trough and W of 110W. Seas of 8 to 10 ft in NW swell, behind the dissipating frontal boundary will continue to propagate across the NE waters mainly N of 27N between 120W and 125W through Sat morning, then will gradually subside. $$ GR