000 AXPZ20 KNHC 310227 TWDEP Tropical Weather Discussion NWS National Hurricane Center Miami FL 0227 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 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 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 08N78W to 08N82W to 18N92W to 16N99W to 08N112W. The ITCZ continues from 08N112W to beyond 06N140W. Numerous moderate and scattered strong convection is noted within 60 nm of the monsoon trough between 78W and 84W, and within 60 nm of the southern coast of Mexico between 96W and 99W. Scattered moderate convection is occurring from 03N to 06N between 81W and 85W, within 150 nm SE of the monsoon trough between 103W and 107W, and from 06N to 09N west of 138W. ...DISCUSSION... OFFSHORE WATERS WITHIN 250 NM OF MEXICO... Fresh to strong W to SW winds with 8-10 ft seas prevail south of a trough of low pressure extending from south of the Gulf of Tehuantepec eastward to Guatemala. Associated winds and seas will gradually subside beginning Fri as this trough moves inland over southern Mexico. Fresh monsoon flow will continue south of the Gulf of Tehuantepec region through Fri night before diminishing as the broad circulation weakens over the area. Seas will subside below 8 ft by Sat. Elsewhere, a high pressure ridge remains 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. Moderate winds are likely found closer to the coast of Baja California Sur between the ridge and a low pressure trough over the Gulf of California. Tranquil conditions prevail over the Gulf of California with light to gentle breezes 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 tightens across the Baja California peninsula with a trough strengthening over the Gulf of California. Looking ahead, moderate NW breezes will prevail west of Baja California through early next week. 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. A low pressure trough off the coast of southern Mexico and Guatemala is producing fresh to strong SW winds with seas to 10 ft over the waters south of Guatemala. Elsewhere, gentle to moderate winds with 6-8 ft seas prevail across the region. 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 moves 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 with this feature. A set of SW swell will move into the offshore waters between Ecuador and the Galapagos Islands this weekend and maintain 8 ft seas through early next week. The latest model guidance indicates the Central American Gyre may finally break down early next week, which would 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 earlier scatterometer data. A 22Z altimeter pass showed 7 ft seas along 132W-134W, and 8 ft seas are likely found closer to 140W within the strongest trades. 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 a reinforcing set of SW swell will move into the southern waters tonight and spread northward through the weekend. Expect 8-9 ft seas south of the Equator this weekend with 8 ft seas reaching as far north as 04N118W by Sat. Wave heights will gradually subside below 8 ft from west to east early next week. $$ Reinhart