631 AXNT20 KNHC 280000 TWDAT Tropical Weather Discussion NWS National Hurricane Center Miami FL 805 PM EDT Mon Aug 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 1800 UTC surface analysis and satellite imagery through 2330 UTC. ...TROPICAL WAVES... An eastern Atlantic tropical wave axis is along 21W from 04N- 20N, moving west at 10-15 kt. The wave is embedded within the broad monsoonal trough region of W Africa. Satellite imagery shows scattered moderate convection in the vicinity of the wave between 14W-23W. A central Atlantic tropical wave axis is along 53W from 04N-20N, moving west at 10-15 kt. The wave is in a rather stable and dry environment. Isolated showers are noted along the wave's axis from 10N-14N. A tropical wave axis in the eastern Caribbean is along 64W from 05N-20N, moving west at 10-15 kt. This wave is well depicted by model guidance and surface observations. Scattered showers are noted south of 10N affecting Venezuela. A tropical wave axis in the western Caribbean is south of 20N along 85W, moving west at 15 kt. Upper-level cyclonic flow west of 77W is enhancing convection in this area. Scattered moderate convection prevails south of 14N between 79W-86W affecting Central America and adjacent waters. ...MONSOON TROUGH/ITCZ... The monsoon trough passes through the coastal sections of Africa near 12N16W to 10N23W to 12N39W. The ITCZ continues from 12N39W to 14N51W. Aside from convection associated with the tropical wave along 21W, scattered moderate convection is within 75 nm on either side of the monsoon trough between 25W-34W. ...DISCUSSION... GULF OF MEXICO... An upper-level trough extends from NE Florida to 23N83W. A ridge prevails over the basin from western Florida to southern Texas. Moist conditionally unstable air across the basin is enhancing scattered showers. The strongest activity is north of 25N near Louisiana. An upper low centered over central Cuba is enhancing convection over the Florida peninsula. A surface trough will develop during the evening hours over the Yucatan Peninsula, then push offshore into the SW Gulf of Mexico at night. A surge of moderate to fresh northeast to east winds will accompany the trough, and enhance convective activity. Gentle to moderate winds expected elsewhere the next few days. CARIBBEAN SEA... Two tropical waves are moving across the basin. Refer to the section above for details. An upper low centered over central Cuba near 20N81W, along with abundant tropical moisture, is inducing scattered showers across Cuba. Convective activity will gradually shift westward as the upper low tracks moves to the W. The eastern part of the eastern Pacific monsoon trough stretches across Panama to Colombia. Scattered showers and thunderstorms are south of 14N between 79W-86W. Fresh to strong winds and building seas to 10 feet will continue in the south-central Caribbean Sea through Wed. A tropical wave along 64W will bring fresh easterly winds and build seas to 7-8 ft as it moves across the basin. Another wave will enter the eastern Caribbean on Wed, increasing the likelihood of scattered showers and thunderstorms over much of the Lesser Antilles. ATLANTIC OCEAN... Two tropical waves are moving across the basin. See the section above for details. An upper low centered over the NW Caribbean is enhancing convection across the western Atlantic W of 77W. A surface trough is between the northern Bahamas and Florida, and another trough was noted in scatterometer data from 27N67W to 23N69W. A weak cyclonic surface rotation is noted between 40W- 50W and north of 28N with scattered showers. The remainder of the basin is influenced by a broad surface ridge N of 30N. For additional information please visit http://www.hurricanes.gov/marine $$ Mundell