297 AXNT20 KNHC 251215 TWDAT Tropical Weather Discussion NWS National Hurricane Center Miami FL 815 AM EDT Wed Jul 25 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 0600 UTC surface analysis and satellite imagery through 1115 UTC. ...TROPICAL WAVES... A tropical wave is over the far eastern Atlantic west of the Cape Verde Islands with axis along 32W extending from 06N-20N, moving westward at 15-20 kt. A large area of Saharan dry air and dust is hindering convective activity from developing at the time. A tropical wave is over the central Atlantic with axis along 45W from 06N-15N, moving westward at 15-20 kt. A large area of Saharan dry air and dust is hindering convective activity from developing at the time. A tropical wave is over the Lesser Antilles with axis along 61W from 08N-18N, moving westward at 15 kt. A large area of Saharan dry air and dust is hindering convective activity from developing at the time. A tropical wave is over the western Caribbean with axis along 80W from central Cuba to central Panama, moving westward at 15-20 kt. Shallow moisture in the northern wave environment along with a region of middle to upper level diffluence ahead of the wave is supporting isolated moderate convection off the coasts of Cuba and Jamaica. In addition, widely scattered moderate convection is over the southern portion of the wave along the coasts of Panama and Costa Rica S of 11N. ...MONSOON TROUGH/ITCZ... The monsoon trough axis extends from the coast of Africa near 12N16W to 10N32W to 08N44W. The ITCZ extends from 08N44W to the coast of South America near 07N58W. Scattered moderate convection is along the coast of W Africa from 06N-12N between 12W-20W. ...DISCUSSION... GULF OF MEXICO... A deep layer trough extends from southern Georgia through the central Gulf of Mexico as seen in water vapor imagery. This feature supports a surface trough that extends from a 1011 mb low pressure over SE Georgia to 27N90W. Diffluence aloft east of this boundary is sustaining convection over the W Atlantic off the Florida coast, while diffluence to the south is producing convection over the south central Gulf of Mexico. Convection is expected to continue over these areas through Thu morning. The Atlc subtropical ridge will then extend an axis SW across the eastern Gulf. Surface ridging is forecast to continue through the weekend, thus providing light to gentle variable flow across the basin. Elsewhere, a surface trough will move off the Yucatan Peninsula into the Bay of Campeche each evening, accompanied by fresh nocturnal winds. Scattered to isolated showers are possible in the Bay of Campeche with the surface trough. CARIBBEAN SEA... Two tropical waves are over the Caribbean. See above. Scattered moderate convection is over N Colombia associated with a 1012 mb low near 09N74W. Isolated showers are located over waters S of Puerto Rico and Hispaniola between 65W and 75W. These showers are being sustained by a small region of shallow moisture and diffluence aloft. Relatively dry and stable conditions persist elsewhere. Expect the surface pressure gradient to support fresh to strong winds in the south-central basin through Fri. Elsewhere, stable conditions with light to moderate winds are expected. ATLANTIC OCEAN... Two more tropical waves are moving across the basin, however all lacking convection due in part to the presence of the dry air of the Saharan Air Layer. Refer to the tropical waves section above for more details. Scattered moderate convection is across the W Atlantic including the northern Bahamas W of 75W. Farther east, a middle to upper level low supports an area of scattered moderate convection from 22N-28N between 56W-64W. Otherwise, the Atlantic subtropical ridge dominates the remainder basin being anchored by a 1032 mb high centered near 37N55W. Expect convection north of the Bahamas through the weekend. The aforementioned 1032 mb subtropical high along with low pressure over the southeast U.S. will produce moderate to fresh southerly winds across the waters north of 25N and west of 70W including Florida coastal waters today. Moderate to fresh winds are also expected south of 22N, including approaches to the Windward Passage. Ridging will dominate the area through the end of the week providing stable and dry conditions in the central Atlantic. For additional information please visit http://www.hurricanes.gov/marine $$ Formosa