446 AXPZ20 KNHC 282046 TWDEP Tropical Weather Discussion NWS National Hurricane Center Miami FL 2045 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 1800 UTC surface analysis and satellite imagery through 2000 UTC. ...SPECIAL FEATURES... A Central American Gyre will develop in the eastern North Pacific within the next couple days. The gyre will move northward toward Central America and southern Mexico. This will advect abundant moisture into portions of Central America through the weekend and into next week. Heavy rainfall is expected over portions of Central America and southern Mexico, especially over southern Guatemala, El Salvador, southern Honduras, and western Nicaragua. This will bring the potential for life-threatening flash floods and mudslides for locations that receive the heaviest rainfall, especially in areas of mountainous terrain. Please refer to products issued by your local weather service for more details. 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 93W north of 08N, moving west around 10 kt. Scattered moderate convection is noted within 180 nm of the wave axis south of 15N. ...INTERTROPICAL CONVERGENCE ZONE/MONSOON TROUGH... The monsoon trough extends from 10N77W to 10N88W to 1012 mb low pressure near 10N108W to 10N124W to 07N137W. The ITCZ extends from 07N137W to 07N140W. Scattered moderate convection is noted within 180 nm of the monsoon trough between 94W and 112W, and within 120 nm of the monsoon trough between 127W and 137W. OFFSHORE WATERS WITHIN 250 NM OF MEXICO... Please see the Special Features section for more details on the Central American Gyre expected to develop within the next couple days, as well as the potential for tropical cyclone formation offshore of southern Mexico. Recent scatterometer data shows light to gentle winds prevail off the coast of Baja California and southern Mexico. Gentle to locally moderate winds are noted near Los Cabos and within the Gulf of California. Seas of 4-6 ft persist over the Baja California Sur offshore waters eastward to near Cabo Corrientes. Wave heights are 5-7 ft over the southern Mexico offshore waters in SW swell. A developing Central American Gyre and possible tropical cyclone formation may produce increased winds and seas over the southern Mexico offshore waters this weekend. Strong to near-gale-force N winds are expected this weekend over the Tehuantepec region. Elsewhere, 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. 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 within the next couple days, as well as the potential for tropical cyclone formation offshore of Central America. Scattered convection persists along the monsoon trough offshore of Guatemala, El Salvador, Nicaragua, and Costa Rica. Moderate S to SW flow is noted on earlier scatterometer data south of the monsoon trough, while light to gentle winds prevail elsewhere across the region. Seas remain in the 4-7 ft range across much of the area, per 16 UTC altimeter data. Hazardous marine conditions will develop Fri into early next week as winds and seas increase over the offshore waters, in association with a developing Central American Gyre and possible tropical cyclone formation. A tropical depression is likely to form within the gyre this weekend offshore of Guatemala and El Salvador and drift northward. Long-period SW swell will continue propagating across the region through early next week. REMAINDER OF THE AREA... Weak 1014 mb low pressure is analyzed near 28N130W, with a surface trough reaching to near 20N132W. Moderate to fresh winds likely persist west of the low center, with wave heights up to 7-8 ft. Low pressure along the monsoon trough near 09N133W is still producing locally fresh winds and 8-9 ft seas. Otherwise, gentle to moderate winds are noted 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 90W and 105W. The low pressure near 28N130W will dissipate by Fri night, allowing for a high pressure ridge to build across the northern waters this weekend. Otherwise, little change in marine conditions is expected over the next couple days. $$ B Reinhart