698 AXNT20 KNHC 271728 TWDAT Tropical Weather Discussion NWS National Hurricane Center Miami FL 128 PM EDT Fri Jul 27 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 1200 UTC surface analysis and satellite imagery through 1715 UTC. ...TROPICAL WAVES... A tropical wave extends across the east Atlantic with axis from 05N-17N along 32W, moving W at 10-15 kt. The wave is being covered by a Saharan air, which is suppressing convection mainly north of 10N. Shallow moisture associated with the monsoon trough and diffluence in the upper-levels support scattered showers along the wave's axis south of 10N. A tropical wave is over central Atlantic with axis extending from 05N-17N along 42W, moving westward at about 10 kt. Intrusion of Saharan dry air and dust to the wave's environment is hindering convection at this time. A tropical wave is over the central Atlantic with axis extending from 06N-19N along 57W, moving westward at about 10 kt. Similar to the tropical wave to the east, Saharan dry air and dust is inhibiting convection with this feature. A tropical wave is over the west-central Caribbean with axis south of 21N along 77W, moving W at 10 kt. Scattered showers are noted along the southern portion of the wave where it meets the monsoon trough S of 12N. ...MONSOON TROUGH/ITCZ... The monsoon trough extends from the coast of Africa near 19N16W to 06N38W. The ITCZ extends from 06N43W to 06N55W. Scattered showers are noted along the monsoon trough between 22W-34W. ...DISCUSSION... GULF OF MEXICO... The Atlantic subtropical ridge extends its axis SW across the basin, thus supporting light to gentle variable winds basin- wide. A surface trough is moving over the Bay of Campeche enhancing winds in this area to moderate levels. The trough will then dissipate this afternoon. This feature will develop again over the next several nights with winds increasing to locally fresh at times. GOES-16 water vapor imagery at lower levels show very dry air in the Gulf. Surface ridging will prevail across the basin through the weekend. Scattered showers are likely over the Bay of Campeche associated with a tropical wave that will move into this region by Sunday. CARIBBEAN SEA... Shallow moisture in the northwest Caribbean with a divergent environment aloft are supporting scattered showers within 90 nm off the coast of Cuba. In the southwest Caribbean, the EPAC's monsoon trough supports scattered showers south of 12N between 75W-83W. This activity is also related to a tropical wave, currently extending along 77W. Refer to the section above for more details. Isolated showers are occurring in the northern Leeward Islands and the Virgin Islands being supported by diffluence aloft associated to an upper-level low centered northeast of Puerto Rico. A new tropical wave is forecast to move across the Lesser Antilles tonight, and a second wave will enter the east Caribbean by Sun night. Otherwise, fresh to strong winds are forecast for the south-central basin through the weekend. ATLANTIC OCEAN... Three tropical waves are moving across the basin. Please refer to the section above for more details. Diffluent flow between the base of an upper-level trough over the southeast CONUS and a high over the northern Bahamas continue to support scattered showers and tstms north of 20N W of 70W. The upper-level trough will prevail through today, enhancing shower and thunderstorm activity over this area. Farther east, a middle level low just north of Hispaniola supports a surface trough that extends from 25N66W to 22N68W. Scattered moderate convection is noted with this features between 64W-70W. The Atlantic subtropical ridge dominates the remainder of the basin being anchored by a 1029 mb high centered near 37N53W. Surface ridging will dominate the central and eastern Atlantic through the weekend providing stable and dry conditions. For additional information please visit http://www.hurricanes.gov/marine $$ ERA