000 AXPZ20 KNHC 280318 TWDEP Tropical Weather Discussion NWS National Hurricane Center Miami FL 218 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 0000 UTC surface analysis and satellite imagery through 0315 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. 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 low 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 90W north of 08N, moving west around 10 kt. Scattered moderate isolated strong convection is noted within 120 nm of the wave axis and north of 04N. ...INTERTROPICAL CONVERGENCE ZONE/MONSOON TROUGH... The monsoon trough extends from 10N86W to 12N96W to 1010 mb low pressure near 09N104W to a 1011 mb low near 10N114W to 1010 mb low near 09N125W to 1011 mb low near 09N134W. The ITCZ extends from 09N134W to beyond 09N140W. Numerous moderate isolated strong convection is noted in the vicinity of the monsoon trough and east of 93W. Scattered moderate convection prevails from 06N-13N between 97W-111W and from 08N-11N between 122W-128W. Scattered showers are noted elsewhere along the boundaries. 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. A weak pressure pattern prevails across the area, with light to gentle winds over much of the forecast waters. Some locally moderate NW winds are noted in recent scatterometer data near Los Cabos. Seas remain 4-6 ft offshore of Baja California, and 5-7 ft in SW swell over the waters south of Cabo Corrientes. Long-period S to SW 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. The monsoon trough remains active offshore of Central America, with numerous showers and thunderstorms N of 04N noted in satellite imagery. Moderate to fresh SW flow prevails south of the monsoon trough, with 4 to 7 ft seas based on latest altimeter data. Note that gusty winds and locally rough seas are likely in and near thunderstorms. Expect increasing winds and seas over the offshore waters late this week and through the weekend, in association with the Central American Gyre and possible tropical cyclone formation. REMAINDER OF THE AREA... Stationary low pressure near 25N130W has weakened the typical high pressure ridge over the northern waters. A surface trough extends from 29N128W to the low to 20N132W. Moderate to fresh winds and seas to 7 ft are noted between this low and high pressure centered near 35N141W. Elsewhere, gentle to locally moderate winds are noted in recent scatterometer passes on either side of the monsoon trough/ITCZ. Multiple low pressure centers prevail along the monsoon trough enhancing winds and seas, as well as convection. A recent altimeter pass near the low centered near 09N104W shows 7-9 ft seas near the low, extending southward beyond the Equator where SW swell lingers over the southern waters. The low pressure near 25N130W will weaken by the end of the week, allowing for high pressure ridge to build across the northern waters. Southerly swell will decay across the far southern waters tonight, allowing wave heights to subside in the area. $$ ERA