FXCA20 KWBC 191924 PMDCA Tropical Discussion - International Desks NWS Weather Prediction Center College Park MD 323 PM EDT Tue May 19 2026 Forecast Bulletin 19 May 2026 at 1930 UTC: Mexico and Northern Central America A mid to upper level ridge extends from the East Pacific Ocean into Mexico and Central America, reaching the southern United States on Tuesday morning. This ridge is favoring subsidence over much of the region, accompanied by dry air in the mid-levels, and inversion caps inhibiting deep convection on Tuesday. To the northwest, a deep mid to upper level trough extends over the southwest United States into the north Baja California Peninsula, interacting with the potent ridge over Mexico. This will enhance short wave troughs along the periphery of the ridge in the mid levels, favoring lower pressures in the low levels of the atmosphere and activating the North American Low Level Jet (LLJ) along the eastern coast of Mexico into southern Texas. This influx of tropical moisture will favor instability over Coahuila and Nuevo Leon, and moderate precipitation totals with a risk of severe weather are expected on Tuesday. Similar conditions are expected along the Sierra Madre Oriental, extending into southern Oaxaca, where light to moderate precipitation totals are expected. By Wednesday, a weakening of the mid to upper level ridge over Mexico and Central America will weaken the trade wind inversions and the subsidence over the region. This will allow for the moisture in the low levels to develop into deeper convection over Central America and Mexico, which have been seeing high surface temperatures. Along the Sierra Madre Oriental, expect moderate precipitation maxima for Wednesday. Into Central America, the diurnal cycle will favor light to locally moderate total precipitation on Wednesday. By Thursday, the upper level trough over the southwest United States will extend a trough axis into the Mexican Plateau by the evening hours. Increasing the instability in the region, expect a slight risk of severe weather in the northern sectors of Coahuila, Nuevo Leon, and Tamaulipas. Expect locally moderate to heavy precipitation in the region. Regions of El Salvador and south Guatemala can expect the effects of a tropical wave that is extending into the region Thursday. Due to the lack of available moisture, expect light to moderate precipitation totals for Thursday. Caribbean and The Bahamas Over the next few days, a retrograding, negatively tilted Tropical Tropospheric Upper Trough (TUTT) is located over The Bahamas and Turks and Caicos, favoring instability for the forecast period. Even with this condition, the generalized low amounts of available moisture in the region will limit heavy precipitation, with the exception of locally higher totals. The areas that can expect light to moderate totals on Tuesday are expected over the Bahamas, Turks and Caicos, Cuba, and Hispaniola. Trace to light precipitation totals could be seen in Puerto Rico/VI and the Lesser Antilles. The presence of a mid to upper level ridge expanding over the Caribbean will favor dry conditions and subsidence over much of the eastern Caribbean on Wednesday. The TUTT will persist over the Bahamas and retrograde into Florida-United States, extending into Cuba and Hispaniola. Similar precipitation totals are expected on Wednesday. The mid to upper level ridge persists into Thursday over the Caribbean, meandering into the west, favoring less precipitation into Hispaniola on Thursday. At the same time, the TUTT remains in the same region as Wednesday, favoring moderate to locally heavy rainfall for the Bahamas, and light to moderate totals for Cuba, Turks and Caicos and Haiti on Thursday. Southern Central America and Northern South America The region of southern Central America and northern South America is seeing the passage of various tropical waves over the forecast period. A wave over Costa Rica and Panama will favor maxima locally reaching 50mm or higher totals in eastern Costa Rica and portions of northwest Panama, light to moderate totals could be expected from the Osa Peninsula through the Azuero Peninsula. In western Colombia, enhanced moist onshore from a trough entering the Gulf of Panama will favor heavy precipitation on Tuesday. On Wednesday, the tropical wave is expected in western Nicaragua, fueling moist onshore flow into eastern Nicaragua and portions of coastal Costa Rica and portions of the Azuero Peninsula. The troughing over the Gulf of Panama will continue to favor heavy precipitation in western Colombia with the upper level support of two interacting upper level high pressure systems. The conditions are expected to continue into Thursday in western Colombia, while the rest of southern Central America can expect light to moderate precipitation. Another tropical wave is located over the Guianas on Tuesday and expected to move into Venezuela on Wednesday. The region can expect enhanced deep convection on Tuesday and Wednesday, while total precipitation between the two days is expected to be moderate to heavy, with locally higher totals possible. On Thursday, the wave is expected over east Colombia, where moderate to locally heavy precipitation totals are expected. A tropical wave currently located over the Atlantic Ocean will arrive into the Guianas and the Amazon Delta by the evening hours of Thursday. Expect this to favor moderate precipitation into the region. TYP SOF INIT 20/00 20/12 21/00 21/12 22/00 22/12 23/00 23/12 TW 07N 33W 37W 40W 44W 48W 51W 54W 55W 58W TW 10N 58W 60W 62W 65W 68W 70W 72W 74W 76W TW 13N 79W 81W 83W 85W 87W 89W 91W 93W 96W TW 13N 101W 105W 108W 113W 115W -- -- Castellanos..(WPC) $$