000 AXPZ20 KNHC 312125 TWDEP Tropical Weather Discussion NWS National Hurricane Center Miami FL 2125 UTC Fri May 31 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 1800 UTC surface analysis and satellite imagery through 2100 UTC. ...SPECIAL FEATURES... ...Heavy Rainfall Potential Over Central America and Southern Mexico... A large, low-level cyclonic circulation called a Central American Gyre will persist across southern Mexico, Central America, and the far eastern Pacific for the next several days. Locally heavy rainfall is likely to continue over portions of Central America and southern Mexico during the next several days. These rains could cause flash flooding and mudslides 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 southern Mexico near 16N99W to 1011 mb low pressure near 13N101W to 09N105W to 08N125W. The ITCZ continues from 08N125W to beyond 06N140W. Scattered moderate and isolated strong convection is noted within 90 nm of the monsoon trough/ITCZ between 115W and 135W. Scattered moderate convection is occurring from 03N to 07N between 80W and 84W, and from 10N to 16N between 90W and 100W. ...DISCUSSION... OFFSHORE WATERS WITHIN 250 NM OF MEXICO... Moderate to fresh SW winds continue south of the Gulf of Tehuantepec with 1011 mb low pressure analyzed near 13N101W and broad low pressure centered over the Yucatan Peninsula. Showers and thunderstorms persist over the southern Mexico offshore waters within this moist monsoon flow. Winds will diminish and seas will subside this weekend through early next week as the pressure pattern weakens over the region and the Central American Gyre finally begins to break down. Farther north, a high pressure ridge north of 20N and west of Baja California is supporting gentle NW breezes off the coast of Baja California Sur per earlier scatterometer data. Moderate to locally fresh NW winds were noted south of Los Cabos. Little change is expected through early next week as fresh winds continue to pulse off Los Cabos with gentle to moderate breezes elsewhere. Moderate to fresh SW gap winds will develop over the northern Gulf of California tonight and persist Sat into Sun between the offshore ridge and a low pressure trough over the Gulf. OFFSHORE WATERS WITHIN 250 NM OF CENTRAL AMERICA, COLOMBIA, AND WITHIN 750 NM OF ECUADOR... Please see the Special Features section for more information about the Central American Gyre, which will continue to bring locally heavy rain to parts of Central America and the adjacent offshore waters through the next several days. Model guidance continues to suggest the Central American Gyre may finally break down early next week, which would support diminishing SW winds offshore. Broad low pressure over the Yucatan Peninsula will maintain persistent monsoon flow with moderate to fresh SW winds off Guatemala through Sat. A weak low pressure area may form along the coast near the border of Chiapas and Guatemala this weekend, but no significant winds or seas are expected at this time. Wind speeds will diminish by early next week with light and variable winds expected over the northern waters. Farther south, seas will build to 8 ft in SW swell between Ecuador and the Galapagos Islands beginning tonight and persisting through Tue. REMAINDER OF THE AREA... A ridge extends from a 1029 mb high pressure centered near 33N141W southeastward toward the Revillagigedo Islands. 18Z scatterometer data revealed a broad region of fresh trade winds from 10N to 20N west of 135W. A 15Z altimeter pass across this area showed 8-9 ft seas near 140W, likely in a broad mix of swell. Farther south, trade wind confluence is still producing scattered showers and thunderstorms along the monsoon trough/ITCZ roughly between 115W and 135W. Elsewhere, recent altimeter data showed 7-9 ft seas south of the Equator between 108W and 110W as SW swell continues to spread into the southern waters. Expect seas to 9 ft to persist south of the Equator this weekend, while 8 ft seas could extend as far north as 07N between 115W and 120W overnight. This swell will propagate northward and reach the coasts of Mexico and Central America this weekend, although wave heights are expected to remain less than 8 ft. Wave heights over the southern waters will gradually subside below 8 ft early next week. $$ Reinhart