000 AXNT20 KNHC 161018 TWDAT Tropical Weather Discussion NWS National Hurricane Center Miami FL 618 AM EDT Wed Aug 16 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 0600 UTC surface analysis and satellite imagery through 1030 UTC. ...SPECIAL FEATURES... Hurricane Gert is centered near 36.0N 68.4W at 16/0900 UTC or about 285 nm NW of Bermuda moving NE at 18 kt. Estimated minimum central pressure is 975 mb. Maximum sustained wind speed is 80 kt with gusts to 100 kt. Numerous moderate to isolated strong convection is from 35N-38N between 66W-70W. See latest NHC forecast/advisory under AWIPS/WMO headers MIATCMAT3/WTNT23 KNHC for more details. ...TROPICAL WAVES... A tropical wave is in the central Atlc associated with a 1011 mb low pressure located near 13N34W. The wave axis extends from 19N34W to the low to 10N34W and has been moving W at 15-20 kt. The wave is in a region of low to moderate vertical wind shear, however intrusion of Saharan dry air and dust to the wave environment limit convection to scattered moderate within 200 nm NW quadrant of low pressure center. Showers and thunderstorms continue to show some signs of organization in association with the area of low pressure. Gradual development of this system is possible before upper-level winds become less conducive for development by the weekend. A tropical wave is E of the Lesser Antilles with axis extending from 21N57W to 10N60W, moving W at 25 kt. The wave is in a region of moderate to strong vertical wind shear and continue to be affected by Saharan dry air and dust, which is limiting convection to scattered to isolated showers within 175 nm of its axis. A tropical wave is in the W Caribbean with axis extending from 21N79W to 09N80W, moving W at 20-25 kt. The wave is in a region of low to moderate vertical wind shear and dry air subsidence, which is limiting convection to isolated showers within 120 nm of its axis. ...ITCZ/MONSOON TROUGH... The monsoon trough extends from the African coast near 12N16W to 09N22W to 13N30W to 13N40W to 14N45W to 12N48W. The Intertropical Convergence Zone axis extends from 12N48W to 10N58W. Outside of convection associated with the tropical waves, scattered heavy showers and isolated tstms are off the W African coast from 08N to 16N E of 22W associated with the next tropical wave that will emerge to E Atlc waters later today. Otherwise, a 1011 mb low embedded in the monsoon trough near 14N45W support scattered showers from 12N to 16N between 43W and 51W. ...DISCUSSION... GULF OF MEXICO... Upper level divergent flow persists over the northern Gulf coast between a broad upper level low centered NW of the Yucatan Peninsula near 22N92W and an upper level anticyclone centered over Georgia adjacent waters near 31N80W. Scattered showers and tstms are occurring over Louisiana adjacent waters N of 27N between 90W- 94W. Isolated showers are over the E Bay of Campeche associated with a surface trough that extends from 23N87W to 17N94W. Otherwise, the E Gulf is under the influence of a surface ridge anchored by a 1017 mb high centered near 27N84W. Gentle to moderate SE flow is W of 90W while light to gentle variable flow is over the eastern half of the basin. The high is expected to persist across the NE Gulf waters through Friday. A surface trough will develop each evening across the Yucatan peninsula shifting W into the Bay of Campeche during the overnight hours. Locally higher winds can be expected in the vicinity of the trough axis. CARIBBEAN SEA... A tropical wave is in the W Caribbean supporting isolated showers and tstms. This tropical wave will continue to propagate westward across the remainder of the basin through tonight. Another tropical wave is E of the Lesser Antilles where it is supporting scattered to isolated showers. This second wave will move into E Caribbean waters later this morning and is forecast to support showers across Puerto Rico and adjacent waters. The wave will move to the central basin Thursday supporting showers across Hispaniola. Diffluent flow between an upper ridge located NE of Jacksonville, Florida and an upper low centered N of Hispaniola continue to support isolated showers over the Windward Passage and E Cuba adjacent waters. Otherwise, fresh to strong winds in the south-central waters are expected through Thursday with moderate to fresh trades elsewhere. ...HISPANIOLA... Showers and tstms are forecast to start overnight due to an approaching tropical that will be entering the E Caribbean this morning. The tropical wave will move over the central Caribbean Thursday supporting showers across the Island. ATLANTIC OCEAN... Trailing moisture associated with Hurricane Gert N of the area continue to support isolated showers in the SW N Atlc between 70W and 76W. Otherwise, the remainder of the basin generally N of 20N is under the influence of the Azores subtropical high which supports fair weather. For information about tropical waves, see section above. For additional information please visit http://www.hurricanes.gov/marine $$ Ramos