000 AXPZ20 KNHC 221543 TWDEP Tropical Weather Discussion NWS National Hurricane Center Miami FL 1605 UTC Sun Sep 22 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 1530 UTC. ...SPECIAL FEATURE... Offshore of Southern Mexico (EP94): Showers and thunderstorms associated with an area of low pressure located less than 200 nm south of the coast of southern Mexico have become better organized since yesterday. Environmental conditions appear conducive for additional development of this system, and a tropical depression could form during the next couple of days while the system drifts slowly northeastward toward the coast of southern Mexico. The chance for this system to develop into a tropical cyclone within the next 48 hours is medium. A Central American Gyre is gradually developing this weekend and will continue through the middle of next week. This scenario, combined with daytime heating and orographic lifting, is expected to generate periods of excessive rainfall over southern Mexico and Central America, as well as the adjacent W Caribbean and E Pacific waters between 80W and 95W. This activity could produce dangerous flash flooding and mudslides across the area. Furthermore, strong to near gale force winds, rough seas and tstms are forecast to affect the offshore waters between Costa Rica and El Salvador from Mon night 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 extends from 12N86W to 1005 mb low near 14N98W to 1007 mb low near 14N113W to 11N140W. Scattered moderate convection is noted from 12N to 19N between 96W and 115W, from 09N to 12N between 121W and 131W, and from 09N to 19N and W of 135W. ...OFFSHORE WATERS WITHIN 250 NM OF MEXICO... Refer to the section above for details on EP94 and the developing Central American Gyre (CAG). A broad surface ridge extends SE to just west of the Baja California offshore waters. Moderate to fresh NW winds have diminished to gentle to moderate speeds over the Baja California offshore waters and moderate seas are now N of Punta Eugenia. Moderate to fresh SW to W winds are across the outer offshore waters of S and SW Mexico associated with a 1008 mb low near 13N99W, which has the potential for some slow development within the next seven days. Light to gentle winds are ongoing along the Gulf of California with slight seas. Otherwise, light to gentle winds and slight to moderate seas are elsewhere. For the forecast, surface ridging will remain in place and fluctuate through today. Gentle to moderate NW winds will continue over the Baja California offshore waters through Wed night. Light to gentle winds will prevail along the Gulf of California through Thu night. An active monsoon trough will support moderate to fresh W to SW winds across the outer SW Mexican offshore waters through Mon. Looking ahead, the low pressure located less than 200 nm south of the coast of southern Mexico has the potential of becoming a tropical depression during the next few of days when the system begins to move slowly eastward or northeastward toward the coast of southern Mexico. Regardless of development, strong to near-gale force winds and rough seas are forecast to affect the S and SW Mexican offshore waters starting Mon night and continuing through the end of the week. ...OFFSHORE WATERS WITHIN 250 NM OF CENTRAL AMERICA, COLOMBIA, AND WITHIN 750 NM OF ECUADOR... Moderate to fresh SW to W winds are ongoing south of the monsoon trough and across the offshore waters from Colombia to Costa Rica along with moderate seas. Gentle to moderate winds and slight to moderate seas prevail elsewhere. Scattered showers and tstms are over the offshore waters between Colombia and Costa Rica due to an active monsoon trough. Strong winds and rough seas are likely in the regions of strongest convection. For the forecast, moderate to fresh southwest to west winds south of the monsoon trough will change little through Mon, then increase to fresh to near gale force speeds across the offshore waters from Costa Rica to Guatemala late Mon through Wed night. Seas will build during this time in mixed swell. The monsoonal flow is expected to become very active, and dominate the region through next week. This pattern will generate increasing westerly wind waves moving into the area waters. Periods of very active weather are also expected across the Central America offshore waters through at least mid week. ...REMAINDER OF THE AREA... Surface ridging prevails N of 15N and W of 120W. The pressure gradient between the ridge and the monsoon trough to the south is resulting in moderate to fresh NE trade winds and moderate seas from 12N to 22N and W of 135W. An area of fresh to strong winds and seas to 8 ft prevails along the monsoon trough from 10N to 15N between 105W and 115W. Gentle to moderate NE to E winds and moderate seas are noted elsewhere N of the monsoon trough. For the forecast, southwest monsoonal winds will continue to become well established through early next week as the monsoon trough lifts slowly northward. Looking ahead, the low pressure located less than 200 nm south of the coast of southern Mexico has the potential of becoming a tropical depression during the next few of days when the system begins to move slowly eastward or northeastward toward the coast of southern Mexico. Regardless of development, strong to near-gale force winds and rough seas are forecast to affect the S and SW Mexican offshore waters starting Mon night and continuing through the end of the week. Another area of low pressure could form well to the southwest of the southwestern coast of Mexico during the next couple of days. Environmental conditions appear conducive for some slow development of this system, and a tropical depression could form during the middle part of the week while the system moves slowly eastward or northeastward. $$ ERA