000 AXPZ20 KNHC 310922 TWDEP Tropical Weather Discussion NWS National Hurricane Center Miami FL 522 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 0600 UTC surface analysis and satellite imagery through 0900 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 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. Currently, satellite imagery shows clusters of moderate to strong convection over parts of SE Mexico, the Gulf of Tehuantepec, and within about 75 nm of the coasts of Oaxaca and Guerrero, particularly between 94W and 100W. Abundant moisture will persist across the region this weekend, extending into the Bay of Campeche. Please refer to your local meteorological service for more details. ...INTERTROPICAL CONVERGENCE ZONE/MONSOON TROUGH... The monsoon trough has moved N and now extends across Central America and southern Mexico entering the eastern Pacific waters through the State of Guerrero to 15N100W to 08N111W. The ITCZ continues from 08N111W to beyond 06N140W. Scattered moderate to isolated strong convection is noted from 04N to 09N between 82W and 86W, and N of 14N between 94W and 100W to the coast of Mexico. Scattered moderate convection is observed from 05N to 08N between 104W and 110W, and from 06N to 09N between 116W and 119W. ...DISCUSSION... OFFSHORE WATERS WITHIN 250 NM OF MEXICO... Gulf of Tehuantepec region: 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 diminish today as this trough moves inland over southern Mexico. Fresh monsoon flow will continue south of the Gulf of Tehuantepec region through late Sat, with seas in the 6-8 ft range as a broad area of low pressure persists over SE Mexico and northern Central America. Elsewhere, a ridge continues to dominate the offshore forecast waters west of the Baja California peninsula producing mainly gentle to moderate NW to N winds. Winds slightly increase near Cabo San Lucas. Little change in this weather pattern is expected for the next several days, with fresh winds pulsing at night near Los Cabos. 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 part of the Gulf Fri night through Sun in association with the presence of the Sonora low, also called the Mexican low. Gentle breezes will persist over the remainder of the Gulf during the next several days. 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. The latest model guidance indicates the Central American Gyre may finally break down early next week, which would support diminishing SW winds offshore. A trough off low pressure 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 and El Salvador based on latest altimeter data. 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 aforementioned trough moves inland over southern Mexico today. Another weak low pressure area may form along the coast near the border of Chiapas and Guatemala during the weekend, 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 late this weekend and maintain seas to 8 ft through early next week. REMAINDER OF THE AREA... A ridge, extending from a 1027 mb high pressure located near 34N139W, dominates the northern forecast waters. Scatterometer data provide observations of gentle to moderate winds under the influence of the ridge. This system will continue to control the weather pattern across the area during the upcoming weekend while strengthen some. The pressure gradient between the ridge and lower pressure in the vicinity of the ITCZ will support moderate to fresh trade winds W of 125W. A small area of 8 ft seas in northerly swell will reach the forecast region by early Sat morning affecting mainly the waters N of 28N between 125W and 132W. Long period, cross-equatorial SW swell continues to dominate much of the forecast waters east of 120W. A new set of SW swell will move into the southern waters today and propagate northward through the weekend, reaching the coasts of Mexico and Central America late Sun into Mon. Expect 8-9 ft seas south of the Equator this weekend, with 8 ft seas reaching as far north as 07N between 110W and 124W by Sat. Wave heights will gradually subside below 8 ft from west to east early next week. $$ GR