601 AXNT20 KNHC 270604 TWDAT Tropical Weather Discussion NWS National Hurricane Center Miami FL 204 AM 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 0000 UTC surface analysis and satellite imagery through 0545 UTC. ...TROPICAL WAVES... A tropical wave is near the Cabo Verde Islands with axis extending from 06N-17N along 26W, moving W at 10-15 kt. The wave is in a low deep layer wind shear environment, however is being covered by a Saharan Air Layer outbreak, which dry air and dust suppress convection N of 10N. Shallow moisture associated with the monsoon and diffluence in the upper levels support scattered moderate convection from 06N-10N between 20W-32W. A tropical wave is over central Atlantic with axis extending from 05N-17N along 40W, moving westward at 10-15 kt. Intrusion of Saharan dry air and dust to the wave environment along with strong deep layer wind shear hinder convection at the time. A tropical wave is over the central Atlantic with axis extending from 06N-20N along 55W, moving westward at 10-15 kt. Similar to the tropical wave to the E, strong deep layer wind shear and Saharan dry air and dust hinder convection at the time. A tropical wave is over the central Caribbean with axis S of 20N along 74W, moving W at 10-15 kt. Both GOES-16 water vapor imagery and CIRA LPW imagery at lower levels show a very dry environment in this region of the basin that along with strong deep layer wind shear suppress convection at the time. ...MONSOON TROUGH/ITCZ... The monsoon trough axis extends from the coast of Africa near 12N16W to 07N27W to 06N38W. The ITCZ extends from 05N42W to 04N51W. For convection information, see the tropical waves section. Otherwise, isolated showers are within 90 nm either side of the monsoon trough and ITCZ. ...DISCUSSION... GULF OF MEXICO... The Atlantic subtropical ridge extends an axis SW across the Florida peninsula and into the E Gulf, thus supporting light to gentle variable winds basin-wide. A surface trough inland the Yucatan Peninsula will move into the Bay of Campeche this morning enhancing the winds in the eastern half of the SW gulf to moderate. The trough will then dissipate near sunrise. This feature will continue the next several night 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 middle of next week with winds becoming southeast on Mon. Otherwise, isolated showers and tstms are likely in the Bay of Campeche associated with a tropical wave that will move into this region Sunday. CARIBBEAN SEA... Shallow moisture in the NW Caribbean, low deep layer wind shear along with a divergent environment aloft are supporting heavy showers and tstms within 90 nm off the coast of Cuba. In the SW Caribbean, the EPAC monsoon continue to support scattered showers and tstms within 105 nm of the coast of NW Colombia, Panama and Costa Rica. Isolated showers are occurring in the northern Leeward Islands and the Virgin Islands being supported by diffluence aloft associated to an upper level low NE of Puerto Rico. A tropical wave moves over the central basin, however general hostile conditions across the basin associated with strong shear and dry air hinder convection at the time. See the waves section for further details. A new tropical wave is forecast to move across the Lesser Antilles tonight...a second wave will enter the E Caribbean 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 tropical waves section above for more details. Diffluent flow between the base of an upper trough over the SE CONUS and a high over the northern Bahamas continue to support scattered showers and tstms N of 23N W of 70W. The upper trough will prevail through today, enhancing shower and thunderstorm activity over this area. Farther east, a middle level low just N of the Mona passage supports a surface trough that extends from 20N68W to 27N66W along with scattered showers and isolated tstms from 21N to 27N between 65W and 70W. The Atlantic subtropical ridge dominates the remainder of the basin being anchored by a 1030 mb high centered near 37N51W. Surface ridging will dominate the central and eastern Atlantic through the end of the week providing stable and dry conditions. For additional information please visit http://www.hurricanes.gov/marine $$ Ramos