Eastern Pacific Tropical Weather Discussion
061 AXPZ20 KNHC 231553 TWDEP Tropical Weather Discussion NWS National Hurricane Center Miami FL 1605 UTC Sun Aug 23 2026 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... Tropical Storm Iselle forms today well offshore of Mexico. It is centered near 15.3N 114.2W at 23/1500 UTC, moving west-northwest at 10 kt. Estimated minimum central pressure is 1003 mb. Maximum sustained wind speed is 40 kt with gusts to 50 kt. Numerous moderate to strong convection is noted within 180 nm W semicircle and 90 nm E semicircle of center. A northwestward motion is expected through Monday, followed by a gradual turn back toward the west- northwest on Tuesday. Some strengthening is forecast during the next couple of days, and Iselle could become a hurricane late Monday or early Tuesday. The outer periphery of Iselle will bring strong winds and rough seas to the Revillagigedo Islands today. Tropical storm conditions are possible today, and storm conditions are expected tonight. 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 Iselle NHC Forecast/Advisory and Public Advisory at www.hurricanes.gov for more details. Central East Pacific (EP91): Disorganized showers and thunderstorms are persisting with a broad area of low pressure located well to the south-southwest of the southern tip of the Baja California Peninsula. Environmental conditions could support the development of a short-lived tropical depression during the next day or two before it interacts or merges with T.S. Iselle. This system has a medium chance for tropical cyclone formation through 48 hrs, and also through 7 days. Please refer to the latest NHC Tropical Weather Outlook at website: https://www.nhc.noaa.gov/text/MIATWOEP.shtml for more details on these systems. ...TROPICAL WAVES... A tropical wave is along 86W/87W from 04N to 20N moving westward at 15 kt. A cluster of moderate to isolated strong convection is noted from 10N to 12N between 80W and 85W. this convective activity is affecting southern Nicaragua and northern Costa Rica. A tropical wave is along 100W N of 04N to near Acapulco, Mexico, moving westward at 15 kt. Scattered moderate to isolated strong convection is observed from 10N to 16N between 96W and 105W. ...INTERTROPICAL CONVERGENCE ZONE/MONSOON TROUGH... The monsoon trough extends from 09N84W to 07N100W to 15N110W to 10N123W to beyond 06N140W. Aside from the convection related to the tropical waves, Invest area EP91 and T.S. Iselle described above, scattered moderate to isolated strong convection can be found from 06N to 13N between 90W and 97W, and from 03N to 10N W of 130W. ...OFFSHORE WATERS WITHIN 250 NM OF MEXICO... Please see the Special Features section for more information about recently upgraded T.S. Iselle and Invest area EP91. A ridge continues to dominate the offshore forecast waters of Baja California Norte supporting gentle to moderate NW winds and moderate seas. Winds and seas associated with the outer periphery of T.S. Iselle are reaching the Revillagigedo Islands. gentle to moderate Se to S winds are occurring in the Gulf of california with slight to moderate seas. The highest seas are near the entrance to the Gulf. Fresh to strong N gap winds are across the Gulf of Tehuantepec region and downwind to about 14N. Seas are up to 8 ft with these winds. For the forecast, Tropical Storm Iselle will move to 16.5N 115.6W this evening, 17.9N 117.2W Mon morning, strengthen to a hurricane near 19.3N 118.7W Mon evening, 20.5N 120.3W Tue morning, weaken to a tropical storm near 21.4N 121.9W Tue evening, and 22.0N 123.6W Wed morning. Iselle will change little in intensity as it moves to near 23.0N 127.2W early Thu. Fresh northerly gap winds will continue to pulse to strong speeds over the Gulf of Tehuantepec during the overnight into the early morning hours through the next several days, with seas occasionally building to 8 ft. A ridge will continue to dominate the offshore forecast waters of Baja California Norte today, supporting mainly gentle to moderate winds. Southerly wind flow will become fresh to locally strong over the north and central parts of the Gulf of California today. ...OFFSHORE WATERS WITHIN 250 NM OF CENTRAL AMERICA, COLOMBIA, AND WITHIN 750 NM OF ECUADOR... Fresh to strong NE to E gap winds continue across the Papagayo region and downwind to near 91W, where seas are 6 to 8 ft. Moderate or weaker winds are found elsewhere, with moderate seas in S swell. For the forecast, high pressure will persist over the eastern Gulf of America and northwestern Caribbean into early next week, leading to fresh NE to E gap winds pulsing to strong speeds over the Papagayo region each evening and night. Moderate to fresh winds extending well downwind of Papagayo will impact the outer waters offshore of El Salvador and Guatemala through the middle of the week. South of the monsoon trough, gentle to locally moderate winds will persist through Wed night. Mainly moderate seas will prevail away from the Gulf of Papagayo through the forecast period. ...REMAINDER OF THE AREA... Please see the Special Features section for more information about recently upgraded T.S. Iselle and the Invest area EP91. High pressure of 1024 mb located near 42N133W extends a ridge southeastward into the northern forecast waters to offshore of Baja California Norte, supporting moderate to locally fresh NE to E winds from 10N to 26N W of 130W. Moderate or weaker winds and moderate seas in mixed swell prevail elsewhere. For the forecast, Another area of low pressure is expected to develop well south of the southern tip of the Baja California Peninsula during the middle portion of this week. Some slow development is expected thereafter, and a tropical depression could form by the end of the week while the system moves generally west-northwestward. This system has a medium chance for tropical cyclone formation through 7 days.