000 AXPZ20 KNHC 281515 TWDEP Tropical Weather Discussion NWS National Hurricane Center Miami FL 1515 UTC Thu May 28 2020 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 1200 UTC surface analysis and satellite imagery through 1500 UTC. ...SPECIAL FEATURES... A Central American Gyre will develop in the eastern North Pacific by the end of the week. The gyre will move northward toward Central America and southern Mexico. This will advect abundant moisture into portions of Central America by the end of the week, through the weekend, and into next week. There is the potential for heavy rainfall over portions of Central America, especially from northern Costa Rica northward into southern Mexico. This will bring the potential for life-threatening flash floods and mudslides for the areas that receive the heaviest rainfall, especially in areas of mountainous terrain. Please refer to products issued by your local weather service for more information. Tropical cyclogenesis is possible in association with Central American Gyres. There is currently a medium chance of tropical cyclone formation within the gyre over the next couple of days, and a high chance of tropical cyclone formation within the next five days. Please see the latest Tropical Weather Outlook for more information. ...TROPICAL WAVES... The axis of a tropical wave is along 92W north of 08N, moving west around 10 kt. Scattered moderate convection is noted within 120 nm of the wave axis south of 15N. ...INTERTROPICAL CONVERGENCE ZONE/MONSOON TROUGH... The monsoon trough extends from 09N80W to 07N84W to 10N106W to 1010 mb low pressure near 09N123W to 1010 mb low pressure near 09N133W to 08N135W. The ITCZ extends from 08N135W to 07N140W. Scattered moderate convection is noted within 240 nm S of the monsoon trough E of 93W, from 06N to 11N between 100W and 114W, and within 120 nm of the monsoon trough between 123W and 135W. OFFSHORE WATERS WITHIN 250 NM OF MEXICO... Please see the Special Features section for more details on the Central American Gyre expected to develop by the end of the week, as well as the potential for tropical cyclone formation offshore of southern Mexico. Light to gentle winds prevail off Baja California this morning under a very weak pressure pattern. Gentle to locally moderate SE winds are likely occurring over the southern Gulf of California. Elsewhere, gentle winds continue off the coast of southern Mexico. Recent altimeter data indicates that seas to 8 ft in SW swell have reached 10N100W, and likely extend into the far offshore waters SW of the Tehuantepec region. Long-period southerly swell will continue propagating across the southern offshore waters through the weekend. High pressure will build over the northern waters Fri night into the weekend, resulting in moderate to fresh NW winds off the coast of Baja California. Expect increasing winds and seas over the southern Mexico offshore waters this weekend in association with the Central American Gyre and possible tropical cyclone formation. OFFSHORE WATERS WITHIN 250 NM OF CENTRAL AMERICA, COLOMBIA, AND WITHIN 750 NM OF ECUADOR... Please see the Special Features section for more details on the Central American Gyre expected to develop by the end of the week, as well as the potential for tropical cyclone formation offshore of Central America. Recent satellite and lightning data indicates the coverage of convection has temporarily diminished along the monsoon trough over the offshore waters. Moderate to fresh SW flow continues south of the trough, with 5-7 ft seas based on 11 UTC altimeter data. North of the trough, generally gentle winds prevail with 4-6 ft seas. Hazardous marine conditions will develop as winds and seas increase over the offshore waters Fri into early next week, in association with the Central American Gyre and possible tropical cyclone formation. REMAINDER OF THE AREA... Stationary low pressure remains over the northern waters near 27N130W, with a surface trough extending to 20N134W. The pressure gradient between this low and high pressure to the NW supports moderate to fresh winds with seas to 8 ft over the NW portion. Fresh winds were noted in overnight scatterometer data near low pressure analyzed along the monsoon trough near 09N133W. Elsewhere, winds remain gentle to moderate on either side of the monsoon trough/ITCZ. An area of 8-10 ft seas in SW swell persists roughly from 04N to 11N between 95W and 105W. Farther west, wave heights peak around 7-8 ft near enhanced winds along the monsoon trough. The low pressure near 27N130W will dissipate by Fri night, allowing for a high pressure ridge to build across the northern waters. Otherwise, little change in marine conditions is expected over the next couple days. $$ B Reinhart