000 AXPZ20 KNHC 250915 TWDEP Tropical Weather Discussion NWS National Hurricane Center Miami FL 1005 UTC Wed Sep 25 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 0600 UTC surface analysis and satellite imagery through 0900 UTC. ...SPECIAL FEATURES... An area of low pressure, partially associated with the remnants of John, is producing a large area of shower and thunderstorm activity along and offshore of the coast of southern Mexico. A 1001 mb low center is embedded within the area of low pressure near 16N103W. In addition to aforementioned showers and thunderstorms, numerous strong thunderstorms are within 180 nm of the low in the W semicircle, and within 90 nm of the low in the E semicircle. Strong to near gale winds southwest winds are south of the low with significant wave heights of 12 to 14 ft. The shower and thunderstorm activity is showing signs of organization, and environmental conditions appear conducive for additional development. A tropical depression is now likely to form in the next day or two, as long as the system remains over water. Interests in southern Mexico should monitor the progress of this system. Regardless of development, this system is expected to produce heavy rainfall with the potential for flash flooding and mudslides over a large portion of southern Mexico this week. This system has a high chance of becoming a tropical cyclone during the next 48 hours. Please refer to the latest NHC Tropical Weather Outlook at www.hurricanes.gov for more details. A Central American Gyre will continue to produce periods of excessive rainfall over southern Mexico and Central America for the remainder of the week, as well as the adjacent western Caribbean and eastern Pacific waters between 80W and 95W. This scenario, combined with daytime heating and orographic lifting, could produce dangerous flash flooding and mudslides across the area. Furthermore, strong to near gale force winds, rough seas and heavy thunderstorms are forecast to affect the offshore waters between Costa Rica and Guatemala through the end of the week. Please follow the forecasts from your local weather offices for more detailed information. ...INTERTROPICAL CONVERGENCE ZONE/MONSOON TROUGH... The monsoon trough axis is southwest of the Special Features 1001 mb low that is near 16N103W. It extends from 13N106W to 14N118W to 11N130W and to beyond 10N140W. Aside from convection related to the trough and low pressure offshore Mexico and the Central American Gyre, scattered moderate convection is seen within 120 nm south of the trough between 106W and 110W, and within 60 nm south of the trough between 116W and 120W. ...OFFSHORE WATERS WITHIN 250 NM OF MEXICO... Please refer to the Special Features section above for information on low pressure offshore Mexico that has potential for tropical cyclone formation and on the Central American Gyre (CAG). High pressure ridging extends into the area from 30N140W southeastward to near 21N122W. Moderate to fresh northwest winds are over the offshore waters of Baja California along with seas of 4 to 6 ft. Light to gentle winds are over the Gulf of California, where seas are 1 to 3 ft, except for higher seas of 3 to 4 ft over the southern section and 4 to 6 ft at the entrance to the Gulf. To the south of the Gulf, latest ASCAT satellite data passes reveal strong to near gale southwest winds from 10N to 16N between 98W and 104W. Seas with these winds are 11 to 14 ft. Fresh to strong southwest winds are elsewhere from 08N to 16N between 97W and 105W, and from 08N to 14N between 105W and 115W. Seas are 8 to 10 ft with these winds. For the forecast, fresh to strong southwest to west winds will continue through Fri, mainly south of 16N between 95W and 105W. Winds will slowly diminish below strong speeds on Sat, and diminish further on Sun. Periods of near gale force winds will be possible through Thu. Rough to locally very rough seas are expected off the coasts of Guerrero and Oaxaca through at least Fri, before they begin to slowly subside. Elsewhere, mostly fresh northwest winds and moderate seas will occur across the remainder of the Mexican offshore waters through Sat, with the exception of the Gulf of California, where winds will remain light to gentle. ...OFFSHORE WATERS WITHIN 250 NM OF CENTRAL AMERICA, COLOMBIA, AND WITHIN 750 NM OF ECUADOR... Please refer to the Special Features section above for information on the Central American Gyre (CAG). Moderate to fresh southwest winds are over the offshore waters of Central America, while moderate south to southwest winds are over offshore waters of Colombia and Ecuador. Seas of 6 to 9 ft in long-period west swell are over the Guatemala and El Salvador offshore waters. Seas are 4 to 6 ft elsewhere over the Central American offshore waters. Scattered to numerous showers and thunderstorms are over the majority of the offshore waters. Some of this activity may produce strong gusty winds rough seas. For the forecast, mostly fresh southwest to west winds will continue over the offshore waters north of Costa Rica today before diminishing to gentle to moderate speeds. Elsewhere, gentle to moderate southwest winds will continue over the forecast waters through the forecast period. Seas will subside slightly north of Costa Rica toward the end of the week. Scattered to numerous showers and thunderstorms will continue over most of the offshore waters through the rest of the week. ...REMAINDER OF THE AREA... Fresh to strong southwest to west winds and rough seas are south of the monsoon trough from 08N to 14N east of about 115W. Seas with these winds are 8 to 10 ft. Moderate to fresh south to southwest winds are elsewhere south of the monsoon trough along with seas of 5 to 6 ft. ASCAT satellite data passes from last night indicated gentle to moderate north to northeast winds elsewhere. Latest satellite altimeter data passes display seas of 5 to 6 ft elsewhere. For the forecast, the fresh to strong southwest to west winds that are south of the monsoon trough will gradually begin to diminish in coverage starting Fri. Seas will be slow in subsiding with these winds. Otherwise, little change is expected elsewhere going into Sat. $$ Aguirre