920 AXNT20 KNHC 191205 TWDAT Tropical Weather Discussion NWS National Hurricane Center Miami FL 804 AM EDT Thu Jul 19 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 1145 UTC. ...SPECIAL FEATURES... SW Caribbean Sea gale warning: A gale is in effect along the coast of Colombia from 11N to 12.5N between 74W and 76W, with seas of 8 to 11 ft. The gale ends today at 1200 UTC. Please read the High Seas Forecast, under the AWIPS/WMO headers HSFAT2/FZNT02 KNHC, for more details. ...TROPICAL WAVES... A tropical wave is W of the Cabo Verde Islands, with an axis extending from 03N30W to 17N30W, moving westward at 10 to 15 kt. Saharan Air Layer (SAL) dry air and dust continue to affect the wave environment, thus hindering convection at this time. A tropical wave is in the E Caribbean with axis S of 20N along 64W, moving westward at 15 to 20 kt. The wave is being intruded upon by Saharan dry air and dust limiting convection to scattered moderate and isolated thunderstorms N of 12N between 60W and 70W. ...MONSOON TROUGH/ITCZ... The monsoon trough axis extends from W Africa near 14N17W to 08N30W to 06N40W, where the ITCZ begins and continues to South America near 05N52W. Scattered moderate convection is from 07N to 16N E of 20W, from 07N to 10N between 20W and 27W, and from 04N to 07N W of 43W. ...DISCUSSION... GULF OF MEXICO... The western periphery of Atlantic high pressure ridging extends E to W over the far eastern gulf waters. Light to moderate anticyclonic flow prevails over the region, except for the NE Gulf where a surface trough extends from 30N84W to 27N90W. Scattered moderate convection and thunderstorms associated with it are N of 27N E of 91W. This activity is also being enhanced by an upper-level trough over and to the NE of the area. The troughing and associated thunderstorm activity is expected to remain over this area for at least the next day or so. Weak high pressure is forecast to prevail across the central gulf waters through Thu night. Thereafter, a frontal trough will cross the NE gulf, forcing the ridge axis farther south over the SE Gulf. Increasing winds are expected over the NE gulf with this frontal trough in the area. Otherwise, a surface trough will move westward off the Yucatan Peninsula the next few evenings, enhancing nocturnal winds over the eastern half of the Bay of Campeche. CARIBBEAN SEA... Please read the Special Features section for details about the pulsing gale force winds in the far SW Caribbean near the coast of Colombia. A tropical wave over the eastern Caribbean will continue to support scattered showers and tstms through early Friday. Mostly fresh E winds will continue over the central Caribbean Sea, and strong NE-E winds will be over the SW and S central sections of the Caribbean, through Sat. ATLANTIC OCEAN... An upper-level trough over the SE United States is enhancing scattered showers and thunderstorm activity N of 28N between 72W and 78W. These thunderstorms will remain active today as a portion of the trough moves off the eastern seaboard. High pressure will build in the wake of this trough late this week. A 1032 mb high well north of the area, centered NW of the Azores Islands is dominating much of the central and eastern Atlantic discussion waters. A large area of Saharan Air Layer (SAL) dust is currently over the central Atlantic from 10N to 25N and between 51W and 66W, and over the eastern Atlantic S of 25N E of 51W. The dust will continue to translate westward for the rest of the week. For additional information please visit http://www.hurricanes.gov/marine $$ MRF/NR