000 AXPZ20 KNHC 201530 TWDEP Tropical Weather Discussion NWS National Hurricane Center Miami FL 1605 UTC Tue Aug 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 1440 UTC. ...SPECIAL FEATURES... Tropical Storm Gilma: is centered near 16.0N 119.6W at 20/1500 UTC, moving west-northwest at 10 kt. Estimated minimum central pressure is 1000 mb. Maximum sustained wind speed is 45 kt with gusts to 55 kt. Peak seas are around 16 ft. Numerous moderate scattered strong convection is noted within 420 nm in the SW semicircle of Gilma. A slightly slower motion to the west- northwest is expected during the next few days. Steady strengthening is expected, and Gilma is forecast to become a hurricane by Wed night. Please read the latest HIGH SEAS FORECAST issued by the National Hurricane Center at website - https://www.nhc.noaa.gov/text/MIAHSFEP2.shtml and the latest Gilma NHC Forecast/Advisory and Public Advisory at www.hurricanes.gov for more details. Well East-southeast of the Hawaiian Islands (EP90/EP91): A large area of disorganized showers and thunderstorms is associated with two disturbances over the western portion of the East Pacific basin, EP90 centered near 10.5N137.5W, and EP91 centered near 14N132W, both at 1007 mb. Scattered moderate convection is within 120 nm in the SW semicircle of EP90, with numerous moderate isolated strong convection within 135 nm in the SW semicircle. Associated winds around these areas are 20 to 25 kt with seas of 8 to 11 ft. These systems are expected to merge later today or tonight, and gradual development is expected after they merge. A tropical depression is likely to form within the next couple of days while the disturbance moves west- northwestward into the Central Pacific basin Wed night or early Thu. Regardless of development, winds are forecast to continue to increase and a Gale Warning is now in effect commencing Thu morning. Information on this system's development can also be found in the Tropical Weather Outlook for the Central Pacific basin. Please refer to hurricanes.gov for the latest. ...TROPICAL WAVES... The southern portion of a tropical wave is near 87W north of 10N to across areas near the Gulf of Papagayo and Gulf of Fonseca and into the far NW Caribbean Sea and Gulf of Honduras, moving west at 15 to 20 kt. Only isolated convection is nearby. ...INTERTROPICAL CONVERGENCE ZONE/MONSOON TROUGH... The monsoon trough extends from 10N85W to 17N111W, then resumes west of Gilma from 16N126W to low pressure, EP91, near 14N132W to low pressure, EP90, near 10.5N137.5W to beyond 10N140W. Scattered moderate isolated strong convection is noted from 04N to 12N between 77W and 90W, and within 240 nm either side of the monsoon trough between 92W and 112W. ...OFFSHORE WATERS WITHIN 250 NM OF MEXICO... Refer to the Special Features section above for details on Tropical Storm Gilma located west-southwest of the Revillagigedo Islands. Fresh to strong N-NE gap winds are blowing across the Gulf of Tehuantepec with nearby seas up to 7 ft. Fresh to strong SE winds are in the northern Gulf of California. Winds are moderate or weaker elsewhere with seas of mainly 5 to 7 ft, except to 8 ft SW of the Revillagigedo Islands associated with Gilma. For the forecast, Tropical Storm Gilma will continue moving farther away from the Revillagigedo Islands today. Pulses of fresh to strong gap winds can be expected in the Tehuantepec region for the next several nights with seas building to around 8 ft. Fresh to locally strong SE winds will pulse in the northern Gulf of California through early Wed. Winds may freshen nearshore Baja California Norte Fri into the weekend. Looking ahead, an area of low pressure is expected to form well to the south of the southwestern coast of Mexico in a couple of days. Environmental conditions should support slow development thereafter, and a tropical depression could form late this week or over the weekend while the system moves west-northwestward over open waters, 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 moderate or weaker winds south of the monsoon trough. Seas are 4 to 6 ft in southerly swell, except 3 to 5 ft offshore Colombia. scattered thunderstorms are offshore northern Colombia to Panama as described above. For the forecast, moderate to fresh easterly winds will pulse in the Gulf of Papagayo during the next several days. Winds will be light to gentle elsewhere north of the monsoon trough, and mainly moderate south of the monsoon trough. Seas may 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 Tropical Storm Gilma, as well as on two disturbances, EP90 and EP91. 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 23N. 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 121.0W this evening, 16.6N 122.6W Wed morning, strengthen to a hurricane near 17.0N 123.9W Wed evening, 17.4N 125.0W Thu morning, 17.8N 126.0W Thu evening, and 18.3N 127.3W Fri morning. Gilma will change little in intensity as it moves to 19.2N 129.7W early Sat. Other than Gilma and the two disturbances, little change in winds and seas is forecast over the next several days. Looking ahead, an area of low pressure is expected to form well to the south of the southwestern coast of Mexico in a couple of days. Environmental conditions should support slow development thereafter, and a tropical depression could form late this week or over the weekend while the system moves west-northwestward over open waters, well offshore of Mexico. $$ Lewitsky