000 AXPZ20 KNHC 010219 TWDEP Tropical Weather Discussion NWS National Hurricane Center Miami FL 0219 UTC Sat Jun 1 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 0000 UTC surface analysis and satellite imagery through 0200 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 08N78W to 08N82W to inland over Central America, then continues from southern Mexico near 16.5N99W to 11N102W to 09N124W. The ITCZ continues from 09N124W to 06N130W to beyond 06.5N140W. Scattered moderate convection is noted within 60 nm of the monsoon trough between 78W and 82W, within 60 nm of the coast of southern Mexico between 98W and 100W, and within 90 nm of the monsoon trough/ITCZ between 118W and 127W. ...DISCUSSION... OFFSHORE WATERS WITHIN 250 NM OF MEXICO... A recent ship observation south of the Gulf of Tehuantepec indicated fresh SW winds continue across portions of the southern Mexico offshore waters. These conditions are supported by broad low pressure over the Yucatan Peninsula. Showers and thunderstorms will persist this weekend over the southern Mexico offshore waters within the moist monsoon flow south of the low pressure area. 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. Elsewhere, a high pressure ridge north of 20N and west of Baja California is supporting gentle to moderate NW breezes off the Baja California coast. Little change in the overall pattern is expected through early next week. Gentle to moderate breezes will prevail in open waters, while fresh NW winds will pulse off Los Cabos in the late afternoon and evening hours. Fresh to locally strong 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 of California. 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 near the Yucatan Peninsula will support 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 tonight and persist through Tue. Seas will briefly subside Tue night and Wed before another set of SW swell approaches the Galapagos Islands Wed night. REMAINDER OF THE AREA... A ridge extends from a 1030 mb high pressure centered near 34N142W southeastward to the Revillagigedo Islands. Earlier scatterometer data from this afternoon revealed a broad region of fresh to locally strong trade winds south of the ridge from 10N to 20N west of 135W. A 2230Z altimeter pass in this area showed 7-9 ft seas from 19N139W to 17N140W, likely in a broad mix of swell and NE wind waves. Farther south, trade wind confluence is still producing scattered showers and thunderstorms along the monsoon trough/ITCZ roughly between 118W and 127W. Elsewhere, a set of SW swell is resulting in 8-9 ft seas south of the Equator roughly west of 105W per recent altimeter data. Another small area of seas to 8 ft is located roughly from 02N to 07N between 115W and 120W based on a 2030Z altimeter pass. Expect 8-9 ft seas to persist south of the Equator this weekend. The swell front will propagate northward and reach the coasts of Mexico and Central America later this weekend, although wave heights are expected to remain less than 8 ft north of the Equator. Wave heights over the southern waters will gradually subside below 8 ft by Tue. Looking ahead, another set of SW swell will approach the far southern waters Wed night. $$ Reinhart