264 AXNT20 KNHC 170005 TWDAT Tropical Weather Discussion NWS National Hurricane Center Miami FL 805 PM EDT Thu Aug 16 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. ...SPECIAL FEATURES... The center of Subtropical Storm Ernesto at 16/2100 UTC is near 43.0N 41.0W, or 1035 km/560 nmi to the ESE of Cape Race in Newfoundland, and about 1305 km/705 nmi to the WNW of the Azores. Ernesto is moving NE, or 045 degrees, 16 knots. The estimated minimum central pressure is 1007 mb. The maximum sustained wind speeds are 40 knots with gusts to 50 knots. Scattered moderate to isolated strong rainshowers cover the waters from 41N to 44N between 37W and 44W. Please read the latest NHC forecast/advisory under AWIPS/WMO headers MIATCPAT5/WTNT35 KNHC for more details. ...TROPICAL WAVES... An Atlantic Ocean tropical wave is along 24W/25W from 17N southward. Rainshowers are possible within 300 nm on either side of the tropical wave. The wave is in a moderate deep layer wind shear environment, and CIRA LPW imagery shows dry air affecting the wave. These two factors are contributing to the lack of convection at this time. An Atlantic Ocean tropical wave is along 52W/53W from 18N southward. The wave is in a low deep layer wind shear environment, and CIRA LPW imagery shows abundant low level moisture associated with it. Scattered to numerous strong rainshowers are from 10N to 13N between 51W and 54W. Widely scattered moderate to isolated strong rainshowers are elsewhere from 07N to 14N between 48W and 60W. A Caribbean Sea tropical wave is along 66W/67W from 20N southward. The wave is in a moderate to strong deep layer wind shear environment. GOES-16 water vapor imagery at the lower levels show very dry air over this region of the Caribbean. Isolated moderate rainshowers cover the Caribbean Sea from 18N southward between 60W and 72W. A tropical wave is moving across the Yucatan Peninsula, from 22N southward. GOES-16 water vapor imagery at the lower levels shows very dry air over this region. Upper level cyclonic wind flow spans the Yucatan Peninsula and the SW corner of the Gulf of Mexico. It is more likely that any nearby precipitation is more related to the upper level cyclonic wind flow and not related to the tropical wave. Scattered to numerous strong rainshowers cover the western parts of the Yucatan Peninsula. ...MONSOON TROUGH/ITCZ... The monsoon trough passes through the coastal sections of Guinea- Bissau near 11N16W, to 09N23W, and 09N33W. The ITCZ continues from 09N33W to 12N42W, and 12N49W. Precipitation: Isolated moderate rainshowers are elsewhere from 06N to 11N from 50W eastward. ...DISCUSSION... GULF OF MEXICO... The Bermuda high extends a ridge axis SW across Florida and large portions of the Gulf to 96W, and weak winds in the range of 5-10 kt prevail in the region. Inflow of shallow moisture from the Caribbean by southeasterly wind along with a middle level inverted trough in the E basin support scattered showers and tstms N of 24N E of 90W. Winds in this region may be slightly higher in the range of 15-20 kt enhanced by the convection. Otherwise, a surface trough is in the W Bay of Campeche supporting scattered heavy showers and tstms within 75 nm of the coast of Vera Cruz. A surface ridge will prevail across the basin through early next week. Rainshowers that are in the NE corner of the area are forecast to continue through Sat night. CARIBBEAN SEA... CIRA LPW imagery shows abundant shallow moisture across most of the Caribbean. In the western basin, diffluent flow aloft supports a broad area of scattered showers and tstms from 11N-18N W of 76W. A tropical wave is moving across the E basin, however both Saharan Air Layer dry air and strong deep layer wind shear are suppressing the development of convection at the time. A ridge north of the area will maintain mainly fresh to occasionally strong trade winds over the south-central Caribbean and moderate to fresh trades elsewhere the next several days. Winds along the coast of Colombia may reach near gale-force at night the next two nights. A large area of showers and thunderstorms associated with a tropical wave along 54W will move west across the tropical N Atlantic tonight through Fri night, reaching the eastern Caribbean Sat. ATLANTIC OCEAN... The Bermuda high and the Azores high covers most of the Atlc ocean mainly supporting fair weather. A weakness in the ridge is analyzed as a 1019 mb low centered near 32N55W from which a surface trough extends SW to 24N63W. Scattered showers and tstms are within 150 nm ahead of the low and trough N of 27N. A large area of disorganized showers and thunderstorms is SE of Lesser Antilles associated with a tropical wave. Some development of this system is possible over the next couple of days while it moves west-northwestward toward the Windward Islands. By late Saturday, unfavorable environmental conditions should limit the chances for additional development while the system moves over the eastern Caribbean Sea. It is likely that this system may bring locally heavy rainfall to portions of the Lesser Antilles on Friday and Saturday. A high pressure ridge along 30N will prevail across the region through the weekend, supporting gentle to moderate trade winds N of 22N and moderate to fresh trade winds S of 22N. Winds may briefly pulse to strong along the N coast of Hispaniola during the late afternoons. For additional information please visit http://www.hurricanes.gov/marine $$ nr/mt