000 AXNT20 KNHC 220005 TWDAT Tropical Weather Discussion NWS National Hurricane Center Miami FL 805 PM EDT Mon May 21 2018 Tropical Weather Discussion for North America, Central America Gulf of Mexico, Caribbean Sea, northern sections of South America, and Atlantic Ocean to the African coast from the Equator to 32N. The following information is based on satellite imagery, weather observations, radar and meteorological analysis. Based on 1800 UTC surface analysis and satellite imagery through 2315 UTC. ...SPECIAL FEATURES... Upper level cyclonic wind flow spans the Gulf of Mexico. A trough extends from the Florida Panhandle, beyond the Yucatan Channel, into the NW Caribbean Sea. This weather pattern is drawing deep tropical moisture northward, from the SW Caribbean Sea between 76W and 84W. A surface trough in the Gulf of Mexico extends from a 1016 mb low pressure center that is just off the coast of the Florida Big Bend near 30N87W. A second surface trough is in the western part of the Caribbean Sea, from 21N86W, across eastern Honduras and NE Nicaragua, to 10N83W in the SW Caribbean Sea. Widely scattered moderate convection and isolated strong rainshowers cover the areas that extend from the SW Caribbean Sea, across Cuba, to Florida, and the Bahamas and the nearby Atlantic Ocean. This activity is expected to continue through at least Tuesday, with heavy rainfall and possible localized flooding. Environmental conditions are expected to be unfavorable for development during the next few days. Some gradual development is possible later this week while the system moves into the central or eastern Gulf of Mexico. Locally heavy rainfall is possible across western Cuba and Florida during the next several days. ...TROPICAL WAVES... A tropical wave is along 33W S of 10N, moving W 10-15 kt. This wave is embedded in a sharp 700 mb trough. Widely scattered moderate convection is from 02S to 05N between 29W and 34W. A tropical wave is over the E Caribbean Sea, along 62W S of 16N, moving W at 10-15 kt. This wave continues to appear as a 700 mb trough and has a poleward surge in moisture associated with it. This wave most likely will weaken over the next 24-36 hours and will be ill defined thereafter. Scattered showers are within 90 nm of the wave axis. ...MONSOON TROUGH/ITCZ... The monsoon trough passes through the coastal sections of Guinea near 09N13W, to 06N14W. The ITCZ continues from 06N14W to 04N27W, and 01N37W. Widely scattered moderate convection is within 90 nm of the ITCZ between 14W-27W. ...DISCUSSION GULF OF MEXICO... Please read the Special Features section for more details about the upper level trough and related surface weather features and precipitation. Scattered rainshowers are from 20N to 22N between 96W and 99W, in the coastal sections of Mexico. This area of precipitation has been moving southward. A surface ridge will remain in the NW Gulf through Thursday night. The current eastern Gulf of Mexico surface trough will drift westward, into the central Gulf of Mexico, by Wednesday. It is possible that a low pressure center may develop in the the NW Caribbean Sea within the next 24 hours, and move northward along the trough into the south central Gulf of Mexico on Friday. CARIBBEAN SEA... Please read the Special Features section for more details about the upper level trough and related surface weather features and precipitation, from the Gulf of Mexico into the NW Caribbean Sea. Upper level cyclonic wind flow cuts across the area, to the north of the line that curves from Hispaniola to 13N67W to 13N60W. This upper level wind flow is around the periphery of the 23N58W Atlantic Ocean cyclonic circulation center. Comparatively drier air in subsidence is apparent in water vapor imagery to the north of the Hispaniola-to-14N60W line. The monsoon trough is along 08N/09N from N Colombia beyond SE Costa Rica, into the eastern Pacific Ocean. Scattered moderate convection is elsewhere from 05N to 11N between 73W and 81W. Atlantic Ocean high pressure will maintain fresh to locally strong trades in the central Caribbean Sea through Friday night. Strong winds, and sea heights to 9 feet, will affect the NW coast of Colombia. A surface trough will linger in the far western Caribbean Sea through Thursday. It is possible that a low pressure center may form along the trough in the Gulf of Honduras on Tuesday, and then move northward into the Gulf of Mexico on Friday. Fresh to strong winds will develop in the central and western Caribbean Sea from Thursday through Friday night, between the surface trough and the Atlantic Ocean high pressure. ATLANTIC OCEAN... Please read the Special Features section for more details about the upper level trough and related surface weather features and precipitation, from the Gulf of Mexico into the NW Caribbean Sea. The chances for heavy rainfall in Florida, across the Bahamas, and in the western Atlantic Ocean will continue. An upper level cyclonic circulation center is near 23N58W. Cyclonic wind flow covers the Atlantic Ocean and parts of the Caribbean Sea from 13N northward between 42W and 74W. An east-to-west oriented ridge will be along 30N through Friday night. The ridge will support fresh to locally strong E to SE winds mainly S of 26N, including the Old Bahama Channel, and the approaches to the Windward Passage through Wednesday. Fresh to occasionally strong winds will prevail N of Hispaniola, mainly at night. It is possible that a broad area of low pressure may develop in the NW Caribbean Sea and move northward across the eastern Gulf of Mexico late in the week. This will cause strong SE to S winds to develop in the waters W of 75W on Friday night. For additional information please visit http://www.hurricanes.gov/marine $$ Formosa