000 AXNT20 KNHC 122341 TWDAT Tropical Weather Discussion NWS National Hurricane Center Miami FL 741 PM EDT Sat Aug 12 2017 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 2315 UTC. ...SPECIAL FEATURES... A 1012 mb low is centered near 24N69W. Scattered moderate to isolated strong convection is noted from 23N-27N between 67W-70W. The low continues to show signs of organization. Conditions remain conducive for development, and a tropical depression is likely to form tonight or Sunday while the system moves northwestward. The low is forecast to turn northward, then northeastward away from the United States early next week. There is a high chance for tropical cyclone formation during the next 48 hours. ...TROPICAL WAVES... A tropical wave is in the far eastern Atlantic west of the Cabo Verde Islands moving west at about 20 kt. The wave axis extends from 20N26W to an embedded 1011 mb low near 11N27W to 08N27W. The wave shows up very well on the SSMI TPW animation and 700 mb streamline analysis. Scattered moderate convection is noted where the wave meets the monsoon trough from 08N-13N between 26W-33W. A tropical wave in the central Atlantic extends from 20N46W to 09N47W. It is moving W at 15-20 kt. The wave coincides with a well defined 700 mb trough, and a high amplitude northward bulge of moisture is noted on the SSMI TPW product. African dust surrounds the wave, which is limiting the associated convective activity. Only isolated moderate convection is seen near the southern end of the wave axis, from 08N-11N between 45W-50W. A tropical wave in the western Caribbean extends from central Cuba at 22N81W to 17N81W to an embedded 1009 mb low near 10N80W, moving W at 20 kt. The wave is in a moist area as seen by SSMI TPW imagery. A pronounced 700 mb trough is over the western Caribbean. Scattered moderate convection is over Cuba from 21N-23N between 78W-82W. Scattered moderate to isolated strong convection is over the SW Caribbean from 10N-15N between 78W-83W. ...ITCZ/MONSOON TROUGH... The monsoon trough extends from the coast of African near 13N17W to 12N20W to 11N32W to 08N46W. The Intertropical Convergence Zone continues from 08N46W to the coast of South America near 08N59W. Aside from convection associated with the tropical waves, scattered moderate convection is noted from 09N-14N between 14W-22W. Isolated moderate convection is from 06N-10N between 33W-43W. ...DISCUSSION... GULF OF MEXICO... A 1018 mb high is centered over the NE Gulf of Mexico near 27N88W. 5-10 kt anticyclonic surface winds are going around the high. Clusters of scattered moderate convection are over most of Florida. More scattered moderate convection is inland over Louisiana, Mississippi, and S Alabama. Further S, scattered moderate convection is over W Cuba, and the N Yucatan Peninsula. In the upper levels, an upper level high is centered over SE Louisiana near 30N90W. Expect over the next 24 hours for the surface high to remain quasi-stationary. Expect convection to persist over the N Gulf, especially during the afternoon and evening hours. CARIBBEAN SEA... A tropical wave is moving through the western Caribbean. See Tropical Waves section for details. The tropical wave will continue to propagate westward, moving west of the area late Sunday night. Fresh to locally strong winds prevail over the south central Caribbean, while gentle to moderate winds are blowing elsewhere. These general conditions will persist through the weekend. The eastern extent of the E Pacific monsoon trough is producing scattered moderate convection over, Costa Rica, and Panama. Further N, widely scattered moderate convection is over E Cuba, Jamaica, Hispaniola, and Puerto Rico. Scattered moderate convection is also inland over Guatemala, El Salvador, Honduras, and Nicaragua. Of note in the upper levels, an upper level low is centered over Jamaica near 18N77W enhancing convection. Expect the tropical wave to move W with convection and showers. Also expect convection to persist over the SW Caribbean. ...HISPANIOLA... Presently widely scattered moderate convection is over Hispaniola, mostly due to an upper level trough. The upper level trough will move W during the next 24 hours, thus a clearing trend is expected. ATLANTIC OCEAN... Please see the special features and tropical wave sections above. A weak surface trough persists across the central Atlantic and extends from 31N50W to 27N56W. Isolated showers are within 60 nm of the trough axis. The Bermuda- Azores high will strengthen over the central Atlantic this weekend. The pressure gradient will tighten between the area of high pressure and the tropical wave currently over the eastern Atlantic this weekend. This will freshen winds north of the tropical wave by Sunday as the wave propagates westward. The Saharan Air Layer tracking product from CIMSS indicates abundant african dust between the two tropical waves currently located across the tropical Atlantic. For additional information please visit http://www.hurricanes.gov/marine $$ Formosa