000 AXPZ20 KNHC 202107 TWDEP Tropical Weather Discussion NWS National Hurricane Center Miami FL 2205 UTC Fri Sep 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 1800 UTC surface analysis and satellite imagery through 2100 UTC. ...SPECIAL FEATURE... A Central American Gyre is gradually developing this weekend and 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 produced dangerous flooding and mudslides across the area. Please follow the forecasts from your local weather offices for more detailed information. ...TROPICAL WAVES... A tropical wave over the far western Caribbean has its axis near 89W and N of 07N, moving westward at about 10 kt. Scattered moderate convection is noted within 240 nm on either side of the wave mainly S of 10N. A tropical wave has its axis along 106W from 05N to 17N. It is moving westward at 10 to 15 kt. No significant convection is noted at this time. A tropical wave has its axis along 123W from 04N to 16N moving westward at about 10 kt. Scattered showers prevail along the wave axis near 11N. ...INTERTROPICAL CONVERGENCE ZONE/MONSOON TROUGH... The monsoon trough extends from 11N86W to a 1008 mb low near 13N98W to 11N121W. ITCZ continues from 11N125W to 10N140W. Aside from the convection associated with the tropical waves described above, scattered moderate to isolated strong convection is from 07N to 15N between 90W and 126W, and from 06N to 14N and W of 134W. ...OFFSHORE WATERS WITHIN 250 NM OF MEXICO... A broad surface ridge extends southeastward into the region. Gentle to moderate northwest winds are over the Baja California offshore waters with slight seas. Along the Gulf of California, light to gentle winds are ongoing, except for moderate to fresh SW winds in the northern Gulf N of 30N. Light to gentle winds and slight seas are elsewhere. For the forecast, the surface ridge will remain in place and fluctuate into the weekend. Gentle to moderate northwest winds over the Baja California offshore waters will increase to fresh speeds this evening and continue through late Sat night, then diminish to gentle to moderate speeds afterward into Mon night. Ongoing moderate to fresh SW winds in the northern Gulf of California will diminish to gentle speeds Sat and then prevail through Tue night. An active monsoon trough will support moderate to fresh W to SW winds across the outer SW Mexican offshore waters tonight through Tue night. Looking ahead, an area of low pressure could form well to the southwest of the southwestern coast of Mexico this weekend. Environmental conditions appear conducive for some slow development of this system, and a tropical depression could form during the next few days while it slowly moves generally northward. Regardless of development, strong to near-gale force winds and rough seas are forecast to affect the outer offshore waters SW of Cabo San Lucas starting Mon night and continuing through the week. ...OFFSHORE WATERS WITHIN 250 NM OF CENTRAL AMERICA, COLOMBIA, AND WITHIN 750 NM OF ECUADOR... Moderate to fresh southwest to west winds are ongoing south of the monsoon trough and across the Central America offshore waters S of 10N, with moderate seas. Gentle to moderate winds and slight seas prevail elsewhere. Scattered moderate convection is over the majority of the Central America offshore waters. Seas are up to 7 ft in the areas of strongest convection offshore Costa Rica. For the forecast, moderate to fresh southwest to west winds south of the monsoon trough will change little through the weekend, then increase to fresh to strong speeds across the offshore waters from Costa Rica to Guatemala Mon through Tue night. Seas will build during this time in mixed swell. The monsoonal flow is expected to become very active, and dominate the region through early 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 waters north of 06N through the weekend and possibly into next week. ...REMAINDER OF THE AREA... Surface ridging extending from a 1028 mb high that is centered well northwest of the area extends east-southeastward to the Baja California Peninsula offshore waters. 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 S of 22N and W of 130W. South of the monsoon trough, fresh SW winds prevail with moderate seas in long-period southeast swell. Slight seas in long-period southerly swell elsewhere S of the monsoon. For the forecast, little overall change is expected over the open Pacific waters W of 120W for the next several days as the aforementioned ridge dominates the region. SW monsoonal winds will continue to become well established through the weekend as the monsoon trough lifts slowly northward. Looking ahead, an area of low pressure could form well to the southwest of the southwestern coast of Mexico this weekend. Environmental conditions appear conducive for some slow development of this system, and a tropical depression could form during the next few days while it slowly moves generally northward. $$ ERA