000 AXNT20 KNHC 120004 TWDAT Tropical Weather Discussion NWS National Hurricane Center Miami FL 804 PM EDT Fri Aug 11 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 1013 mb low is centered N of the Leeward Islands near 22N66W. Scattered moderate convection is from 21N-24N between 64W-67W. Dry air aloft and unfavorable upper-level winds have limited significant development during the past few days. Environmental conditions, however, are expected to become a little more conducive for development during the next day or two, and this system could become a tropical depression over the weekend. The low is forecast to move generally northwestward through the weekend and is likely to turn northeastward away from the United States early next week. The chance for formation during the next 48 hours is medium. ...TROPICAL WAVES... A tropical wave off the coast of W Africa extends from 17N18W to 09N18W, moving W at 15-20 kt. The wave shows up very well on the SSMI TPW animation and 700 mb streamline analysis. Scattered moderate convection is from 12N-14N between 16W-19W. Scattered showers are within 120 nm of the remainder of the wave axis. A tropical wave in the central Atlantic extends from 18N40W to 09N40W. It is moving W at 15-20 kt. The wave is in a moist area as seen by SSMI TPW imagery. The wave has low to moderate vertical wind shear and has extensive Saharan dry air and dust to the west of its environment. Scattered showers are within 120 nm of the wave axis. A tropical wave in the central Caribbean extends from Hispaniola at 19N71W to NW Venezuela near 10N72W, moving W at 10-15 kt. The wave is in a moist area as seen by SSMI TPW imagery. The wave is in a region of low vertical wind shear. A pronounced 700 mb trough is over the central Caribbean. Scattered moderate to isolated strong convection is over Hispaniola from 18N-20N between 70W-75W. Scattered showers are elsewhere within 120 nm of the wave axis. ...ITCZ/MONSOON TROUGH... The monsoon trough extends from the African coast near 13N16W to 10N24W to 11N34W to 07N46W. The Intertropical Convergence Zone axis continues from 07N46W to the South American coast near 06N57W. Aside from convection associated with the tropical waves, scattered moderate convection is from 07N-12N between 20W-34W. ...DISCUSSION... GULF OF MEXICO... A 1020 mb high is centered over the NE Gulf of Mexico near 27N88W. 10 kt anticyclonic surface winds are going around the high. A 1015 mb low is centered over NE Florida near Jacksonville Florida at 30N81W. A surface trough extends S from the low to near Punta Gorda Florida at 27N82W. 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 Yucatan Peninsula. In the upper levels, an upper level high is centered over N Mexico near 30N100W. NE upper level flow covers the Gulf of Mexico. Expect over the next 24 hours for the surface high to remain stationary. Expect the low over NE Florida to lift N. Also expect convection to persist over the N Gulf and the E Gulf especially during the afternoon and evening hours. CARIBBEAN SEA... A tropical wave is along 71W/72W. Please, see Tropical Waves section for details. The most recent scatterometer data indicate fresh to locally strong winds across the south-central Caribbean, in the Gulf of Honduras, and also across the Windward Passage. The eastern extent of the E Pacific monsoon trough is producing scattered moderate convection over the SW Caribbean, Costa Rica, and Panama, S of 13N. 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, and Honduras. Of note in the upper levels, an upper level low is centered over W Honduras near 15N88W enhancing convection. Expect the tropical wave to move W with convection and showers. Also expect convection to persist over the SW Caribbean. ...HISPANIOLA... A tropical wave is presently moving across Hispaniola. The wave together with local effects are producing scattered moderate convection. The tropical wave will move away from the island on Saturday, however an upper-level trough will continue to produce scattered showers and convection during the afternoon and evening hours. Moisture is forecast to diminish across the island on Sunday. ATLANTIC OCEAN... Scattered moderate convection is off the coast of NE Florida N of 27N and W of 76W. Scattered showers are over the N Bahamas. A 1013 mb low is centered N of the Leeward Islands near 22N66W. See above. A surface trough is over the Central Atlantic from 31N44W to 24N50W. Scattered showers are within 120 nm of the trough axis. The remainder of the Atlantic Ocean is under the influence of a ridge anchored by a 1030 mb high pressure located NE of the Azores. In the tropics, a 1011 mb low is centered near the Cape Verde Island at 18N21W. This low is forecast to move move WSW over the islands with scattered showers over the next 24 hours. Of note in the upper levels, an upper level low is also located N of the Leeward Islands near 22N66W, making the system a deep layered low. The upper level low is enhancing showers and convection. Another upper level low is centered over the E Atlantic near 28N41W producing scattered showers within 240 nm of the center. For additional information please visit http://www.hurricanes.gov/marine $$ Formosa