000 AXPZ20 KNHC 302120 TWDEP Tropical Weather Discussion NWS National Hurricane Center Miami FL 2120 UTC Thu May 30 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 that is typical for this time of the year, called a Central American Gyre, will persist across the far eastern tropical Pacific and Central America 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 the southern coast of Mexico near 16N98W to 10N105W to 08N114W. The ITCZ continues from 08N114W to 08N135W to beyond 06N140W. Numerous moderate and isolated strong convection persists from 10N to 16N between 89W and 105W. Scattered moderate convection is noted from 04N to 07N between 79W and 82W. ...DISCUSSION... OFFSHORE WATERS WITHIN 250 NM OF MEXICO... Fresh to strong W to SW winds with 8-11 ft seas prevail south of an elongated area of low pressure located south of the Gulf of Tehuantepec. Associated winds and seas will gradually subside on Fri as this trough moves inland over southern Mexico. Tropical cyclone formation is not anticipated with this system. Fresh monsoon flow south of the Gulf of Tehuantepec region will persist through Fri night before diminishing as the broad circulation weakens and moves westward over the eastern tropical Pacific. Elsewhere, a high pressure ridge is positioned west of the Baja California offshore waters. A partial 18Z scatterometer pass over the northern waters showed light to gentle NW breezes off Baja California Norte. Farther south, 16Z altimeter data showed 7-8 ft seas over the Baja California Sur waters in residual NW swell. Tranquil conditions prevail over the Gulf of California with light and variable winds and seas 3 ft or less. Moderate to fresh SW gap winds are expected over the northern Gulf Fri night through Sat night as the pressure gradient strengthens across the Baja California peninsula. 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. An elongated area of low pressure off the coast of southern Mexico is producing fresh to strong SW winds with seas to 11 ft over the waters south of Guatemala. Elsewhere, gentle to moderate winds with 6-8 ft seas prevail across the remaining forecast waters. The enhanced SW monsoon flow will persist off the coast of Guatemala with fresh winds expected into the weekend. Seas will gradually subside after the low pressure trough tracks inland over southern Mexico on Fri. Another weak low pressure area may form along the coast near the border of Chiapas and Guatemala by Sun, but no significant winds or seas are expected. A set of SW swell will move into the Galapagos offshore waters Fri night and maintain 8 ft seas through early next week. The Central American Gyre may finally break down early next week, which should support diminishing SW winds offshore. REMAINDER OF THE AREA... A high pressure ridge dominates the waters north of 20N with moderate to fresh NE trades generally west of 130W between the ridge and the ITCZ based on partial scatterometer data this afternoon. A 1730Z altimeter pass confirmed 7-8 ft seas continue within the trades along 135W. Moderate to fresh trades will continue for the next several days with little change in the overall pattern expected through early next week. Long period, cross-equatorial SW swell continues to dominate much of the forecast waters south of 15N and east of 120W. Seas will briefly subside as this swell decays, but another set of SW swell will propagate northward tonight through the weekend. Expect 8-9 ft seas south of the Equator this weekend with 8 ft seas reaching as far north as 04N by Sat. $$ Reinhart