105 AXNT20 KNHC 161803 TWDAT Tropical Weather Discussion NWS National Hurricane Center Miami FL 203 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 1200 UTC surface analysis and satellite imagery through 1745 UTC. ...SPECIAL FEATURES... The center of Subtropical Storm Ernesto at 16/1500 UTC is near 42.0N 43.2W, or 510 nmi to the ESE of Cape Race in Newfoundland. Ernesto is moving NE at 14 knots. The estimated minimum central pressure is 1007 mb. The maximum sustained wind speeds are 40 knots with gusts to 50 knots. Scattered moderate convection is from 39N to 46N between 39W and 44W. Please read the latest NHC forecast/advisory under AWIPS/WMO headers MIATCPAT5/WTNT35 KNHC for more details. ...TROPICAL WAVES... A tropical wave is in the E Atlc with axis extending from 06N-17N along 23W, moving W at 10 kt. 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. A tropical wave is in the central Atlc with axis extending from 04N-16N along 49W, moving W at 20 kt. The wave is in a low deep layer wind shear environment, and CIRA LPW imagery shows abundant low level moisture associated with it. These factors along with upper level diffluence support scattered moderate convection and isolated tstms from 07N-18N between 46W-60W. A tropical wave is in the E Caribbean with axis extending from 09N-18N along 65W, moving W at 15-20 kt. 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. There is no convection associated with this wave at this time. A tropical wave is in the Yucatan Peninsula S of 21N with axis along 89W, moving W at 10-15 kt. GOES-16 water vapor imagery at the lower levels shows very dry air over this region, which in part is hindering convection at the time. ...MONSOON TROUGH/ITCZ... The monsoon trough extends from the coast of W Africa near 12N16W to 09N29W. The ITCZ begins near 09N29W and continues to 10N36W to 11N47W. Scattered moderate isolated strong convection is from 11N-14N E of 18W. Isolated moderate convection is within 120 nm either side of the ITCZ between 27W-37W. For more information about convection, see the tropical waves section. ...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. Surface ridging will prevail across the basin through early next week. Showers over the NE basin 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. Otherwise, surface ridging extending from the Atlc continues to support fresh to near gale force winds in the south-central Caribbean that is forecast to continue the next two days...strongest winds will be along the coast of Colombia. A tropical wave within 700 nm SE of the Lesser Antilles will move across the Islands Sat morning along with showers. 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. Regardless of development, this system is likely to bring locally heavy rainfall to portions of the Lesser Antilles on Friday and Saturday. For further information associated with the tropical waves, see section above. For additional information please visit http://www.hurricanes.gov/marine $$ Ramos/Hagen