000 AXNT20 KNHC 232347 TWDAT Tropical Weather Discussion NWS National Hurricane Center Miami FL 747 PM EDT Sat Jun 23 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 2300 UTC. ...TROPICAL WAVES... The axis of a tropical wave is near the west coast of Africa along 18W from 03N-17N. Scattered moderate convection associated to this wave is noted from 04N to 14N between 13W and 22W. The axis of a tropical wave is near 43W from 01N to 18N, moving W at 20 kt. Isolated moderate convection is noted at the base of this wave south of 04N. The axis of a tropical wave is near 59W from 02N to 18N, moving W at 20 kt. Scattered moderate convection is noted from 05N to 11N between 55W and 60W. This wave will move into the eastern Caribbean through tonight. The axis of a tropical wave is near 72W from 10N-20N. This wave, in conjunction with an upper level trough extending across western Hispaniola, is producing a large area of showers and tstms over Hispaniola and the regional waters. This wave will move across the central Caribbean today, and will exit the western Caribbean Sun night. Moisture from this wave will reach eastern Cuba and Jamaica this evening into tonight, increasing the likelihood of showers with embedded tstms. The axis of a tropical wave is near 87W, and extends from the SE Gulf across central America into the eastern north Pacific region. Scattered to numerous showers and tstms are observed where the wave meets the monsoon trough, more concentrated on the EPAC. ...MONSOON TROUGH/ITCZ... The monsoon trough extends off western Africa near 16N17W to 07.5N23W to 06N28W. The ITCZ continues from 06N28W to 05N54W. Outside of the convection associated with the tropical waves, a cluster of moderate convection is noted from 04N to 07N between 25W and 31W. ...DISCUSSION... GULF OF MEXICO... An upper-level low centered near 21.5N98W is helping to induce some showers and tstms across the E Bay of Campeche as well as potions of southern Mexico. The low will drift westward into Mexico through Sun night, and continue to enhance convection across this area. SE wind flow will continue to transport abundant tropical moisture from the Yucatan Peninsula into the western Gulf the remainder of the weekend. A 1018 mb high pressure is located just off SW Florida near 26N83W. A weak ridge extends from this high toward the coast of Texas. The ridge will drift to over the northern gulf early next week. Southeast return flow will increase over the western Gulf between the ridge and weak low pressure over northern Mexico beginning tonight. A trough moving west off the western coast of the Yucatan Peninsula each night will further enhance overnight winds over much of the southwestern gulf waters. CARIBBEAN SEA... A tropical wave is over the far western Caribbean and Central America. Another tropical wave is moving across Hispaniola. Please, see Tropical Waves section for more details. Expect increasing showers and isolated thunderstorms in association with the passage of these tropical waves. Recent scatterometer data provide observations of fresh to strong winds across the south-central Caribbean, with mainly fresh winds over the remainder of the central Caribbean and the eastern part of the basin. Gentle to moderate E-SE winds prevail over the NW Caribbean. The trade winds over the south central Caribbean will strengthen and expand in areal coverage across just about the entire basin through early next week as high pressure builds across the central Atlantic. Winds could reach near gale force along the coast of Colombia tonight. Seas are forecast to build to 10-12 ft over the south-central Caribbean with the strongest winds. Fresh to strong winds are also expected in the Gulf of Honduras at night through at least Mon night. ATLANTIC OCEAN... High pressure of 1029 mb centered near 31N49W extends a ridge westward across the forecast area. The most recent scatterometer passes indicate fresh to locally strong trade winds along the southern periphery of the ridge, particularly S of 18N W of 43W. This high pressure will slowly shift westward through tonight, then remain nearly stationary near 30N55W through Tue night. The tightening pressure gradient over the central Atlantic will continue to support fresh to strong trade winds and seas of 8-9 ft E of the Lesser Antilles to about 45W through tonight. Then, the aerial extent of the fresh to strong trades will decrease on Sun, covering mainly the waters E of the lesser Antilles to about 50W. Fresh to strong winds are also expected off Hispaniola at night. For additional information please visit http://www.hurricanes.gov/marine $$ AL/GR