000 AXPZ20 KNHC 211521 TWDEP Tropical Weather Discussion NWS National Hurricane Center Miami FL 1605 UTC Wed Aug 21 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 1440 UTC. ...SPECIAL FEATURES... Hurricane Gilma: Hurricane Gilma is centered near 16.0N 122.8W at 21/1500 UTC, moving west at 6 kt. Estimated minimum central pressure is 983 mb. Maximum sustained wind speed is 75 kt with gusts to 90 kt. Peak seas are around 26 ft. Numerous moderate to strong convection is noted within 90 nm of the center with scattered moderate convection elsewhere within 240 nm in the SE semicircle and 120 nm in the NW semicircle. A continued slow westward to west-northwestward motion is expected during the next few days. Strengthening is forecast during the next 48 hours, and Gilma could become a major hurricane by the end of the week. Gale Warning Well East-Southeast of the Hawaiian Islands (EP90/EP91): Showers and thunderstorms continue to become better organized in association with a well-defined area of low pressure located well east-southeast of the Hawaiian Islands near 15.5N134.5W (EP91) at 1006 mb. Current associated winds are 20 to 30 kt with seas of 8 to 12 ft. Numerous moderate and isolated strong convection is noted within 240 nm in the SW semicircle. If these trends continue, a tropical depression or tropical storm is likely to develop later today while it moves generally westward at 10 to 15 kt. A weaker disturbance (EP90) located just to its southwest near 11N137.5W is expected to merge with this system later today. There is scattered moderate convection noted within 210 nm in the SW quadrant. This overall system is expected to strengthen as it moves into the central Pacific basin tonight or on Thu and moves near the Hawaiian Islands late this weekend or early next week. This system has a high chance of tropical cyclone formation through the next 48 hours and 7 days. Regardless of development, a Gale Warning is in effect near 140W over our forecast waters beginning Thu morning. Please read the latest HIGH SEAS FORECAST issued by the National Hurricane Center at website - https://www.nhc.noaa.gov/text/MIAHSFEP2.shtml for the latest on EP90/EP91 and Gilma, and the latest Gilma NHC Forecast/Advisory and Public Advisory at www.hurricanes.gov for more details. ...TROPICAL WAVES... The southern portion of a tropical wave is near 94W and the Gulf of Tehuantepec north of 09N to across the Chivela Pass and into the Bay of Campeche, moving west at around 10 kt. Any nearby convection is described in the section below. The southern portion of another tropical wave is near 85W/86W near the Gulf of Papagayo north of 08N to across portions of Central America and into the NW Caribbean Sea, moving west at 20 to 25 kt. Any nearby convection is described in the section below. ...INTERTROPICAL CONVERGENCE ZONE/MONSOON TROUGH... The monsoon trough extends from 09N84W to 09N90W to 16N115W, then resumes well west of Gilma from 16N130W to low pressure, EP91, near 15.5N134.5W to low pressure, EP90, near 11N137.5W to beyond 10N140W. Scattered moderate isolated strong convection is noted from 05N to 11N between 77W and 95W, from 06N to 17N between 98W and 105W, and from 10N to 19N between 106W and 114W. ...OFFSHORE WATERS WITHIN 250 NM OF MEXICO... Fresh to strong N-NE gap winds are blowing across the Gulf of Tehuantepec with nearby seas of 7 to 9 ft. Moderate to fresh SE winds are in the northern Gulf of California. Winds are moderate or weaker elsewhere with seas of mainly 5 to 7 ft. Seas are 2 to 4 ft in the Gulf of California, except 1 to 2 ft in the central portion. For the forecast, gap winds will pulse to fresh to strong in the Tehuantepec region each night into the weekend, with seas at times reaching around 8 ft. Moderate to fresh SE winds will pulse in the northern Gulf of California through at least Thu night. Fresh NW winds are forecast nearshore Baja California Norte Fri into the weekend as high pressure builds southward into the area, and with seas building to around 8 ft at times there. Disorganized showers and thunderstorms continue in association with a trough of low pressure centered several hundred nautical miles southwest of the coast of southwestern Mexico. Environmental conditions are forecast to become more conducive for development in a few days, and a tropical depression is likely to form late this week or over the weekend while the system moves west- northwestward into the central portion of the East Pacific, well offshore of Mexico. ...OFFSHORE WATERS WITHIN 250 NM OF CENTRAL AMERICA, COLOMBIA, AND WITHIN 750 NM OF ECUADOR... Moderate to fresh NE winds are in the Gulf of Papagayo. Winds elsewhere north of the monsoon trough are light to gentle with gentle to moderate winds south of the monsoon trough. Seas are 3 to 6 ft. Scattered to numerous showers and thunderstorms are offshore Colombia, Panama, and Costa Rica as described above. For the forecast, moderate to fresh easterly gap winds will pulse nightly in the Gulf of Papagayo through the next several days. Winds will be light to gentle elsewhere north of the monsoon trough, and gentle to moderate south of the monsoon trough. Seas are likely to build slightly offshore Ecuador to the Galapagos Islands by the end of the week with little change in seas anticipated elsewhere. ...REMAINDER OF THE AREA... Please see the Special Features section for details on Hurricane Gilma, as well as on two disturbances, EP90 and EP91 with an associated Gale Warning and high chance of tropical cyclone formation. Otherwise, the pressure gradient between high pressure centered north of the area and the aforementioned disturbances and Gilma is leading to moderate to fresh trades north of the monsoon trough extending to around 26N. Disorganized showers and thunderstorms in association with a trough of low pressure centered several hundred nautical miles southwest of the coast of southwestern Mexico near 14.5N109.5W, with locally fresh winds. Winds are moderate or weaker elsewhere over the open waters. Seas across the open waters away from Gilma, EP90, and EP91 are 4 to 7 ft. For the forecast, Gilma will move to 16.2N 123.7W this evening, 16.5N 124.8W Thu morning, 16.8N 125.9W Thu evening, 16.9N 127.2W Fri morning, 17.1N 128.5W Fri evening, and 17.3N 130.3W Sat morning. Gilma will change little in intensity as it moves to 17.5N 133.5W early Sun. Meanwhile, environmental conditions are forecast to become more conducive for development of the area currently near 14.5N109.5W in a few days, and a tropical depression is likely to form late this week or over the weekend while the system moves west-northwestward into the central portion of the East Pacific, well offshore of Mexico. Little change in winds and seas is anticipated over the remainder of the open waters through the upcoming weekend. $$ Lewitsky