000 AXPZ20 KNHC 240907 TWDEP Tropical Weather Discussion NWS National Hurricane Center Miami FL 517 UTC Fri May 24 2019 Tropical Weather Discussion for the eastern Pacific Ocean from the Equator to 32N, east of 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... As is typical for this time of year, a large cyclonic gyre, called a Central American Gyre, has developed. This feature is bringing abundant moisture across Central America, which will produce heavy rainfall across portions of Central America for the next few days. Flash flooding and mudslides will be possible in areas of mountainous terrain. Please refer to your local meteorological service for more details. ...INTERTROPICAL CONVERGENCE ZONE/MONSOON TROUGH... The monsoon trough extends from 12N86W to 12.5N89W to 07N119W. The ITCZ continues from 07N119W to 08N123W to beyond 06N140W. Scattered moderate isolated strong convection is noted over the forecast waters from 07N to 12N between 84W and 88W. Numerous moderate scattered strong convection was noted over forecast waters N of 11N between 88W and 95W. Scattered moderate convection was noted from 04N to 09N between 96W and 106W. ...DISCUSSION... OFFSHORE WATERS WITHIN 250 NM OF MEXICO... Overnight scatterometer pass indicates moderate to fresh NW winds prevail off the west coast of the Baja California peninsula with seas in the 8-10 ft range. Gentle to moderate winds prevail over the Gulf of California, with seas 3 ft or less. Gentle to moderate W to NW winds, with seas in the 5-7 ft range prevail over the remainder of the open waters off the coast of Mexico. Winds and seas off the coast of the Baja California peninsula will diminish today. Gulf of California: Gentle to moderate breezes will prevail across the Gulf of California through Sat. By Sat night, SW gap winds will strengthen across the northern Gulf ahead of a cold front approaching the region. Expect strong to near gale force gap winds north of 29.5N Sat night into Sun with strong winds persisting through Sun night. Wind speeds will diminish by early next week. Gulf of Tehuantepec: Fresh to locally strong northerly winds will pulse across the Gulf of Tehuantepec region during the overnight and early morning hours this weekend with the assistance of the nocturnal drainage flow. Seas will build to near 8 ft with these short-lived gap wind events. Fresh northerly winds early Mon will diminish through early next week. OFFSHORE WATERS WITHIN 250 NM OF CENTRAL AMERICA, COLOMBIA, AND WITHIN 750 NM OF ECUADOR... Please see special features above for more on the Central American Gyre which will bring heavy rains to portions of Central America as well as the offshore waters. With Central American Gyres, the monsoon trough lifts northward, with southerly monsoon flow prevailing over the forecast waters for much of the next several days. The monsoon circulation will dominate the regional pattern through early next week. Winds south of the monsoon trough will likely strengthen Mon through Tue, although wind speeds will be highly dependent on how the circulation around the Central America Gyre evolves over the next few days. Seas will generally remain 8 ft or less through the weekend, then build to 8-10 ft early next week as SW swell mixes with locally generated wind waves due to strengthening monsoon flow. REMAINDER OF THE AREA... Northwest swell continues to impact the waters north of 20N. Recent altimeter data indicates seas continue to peak near 11 ft N of 27N between 120W and 123W. This swell will subside the next couple of days, with with seas falling below 8 ft late Sat. A high pressure ridge extends from a 1034 mb high near 36N141W southeastward toward the Revillagigedo Islands. The pressure gradient between this ridge and lower pressure in the vicinity of the ITCZ is maintaining fresh to strong NE trades over the waters from 13N to 20N west of 137W, with seas in the 8-10 ft range. High pressure will weaken today, loosening the pressure gradient and diminishing the winds. Seas will begin to subside in response to the diminishing winds. A set of SW swell will propagate into the southern forecast waters Sun and continue to propagate northward through early next week. This will result in a large area of seas 8 ft or greater south of 10N between 95W and 125W Mon and Tue. $$ AL