000 AXNT20 KNHC 240545 TWDAT Tropical Weather Discussion NWS National Hurricane Center Miami FL 205 AM EDT WED AUG 24 2016 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 0000 UTC surface analysis and satellite imagery through 0515 UTC. ...SPECIAL FEATURES... Tropical Storm Gaston is centered near 14.7N 37.1W at 24/0300 UTC or about 760 nm west of the Cabo Verde Islands moving west- northwest at 15 kt. Estimated minimum central pressure is 1002 mb. Maximum sustained wind speed is 55 kt with gusts to 65 kt. Scattered moderate to isolated strong convection is from 13N-16N between 35W-39W. Isolated moderate convection is from 11N-13N between 35W-39W. Please see the latest NHC Intermediate Public Advisory under AWIPS/WMO headers MIATCPAT2/WTNT32 KNHC and the full Forecast/Advisory under the AWIPS/WMO headers MIATCPAT2/WTNT22 KNHC for more details. A tropical wave west of the Lesser Antilles is analyzed from 22N64W through a 1009 mb low near 16N60W to 11N57W. This system could become a tropical depression during the next day or two as it moves west-northwest 13 to 17 kt. Conditions could become more conducive later this week while the system moves near the southeastern and central Bahamas. Scattered moderate to isolated strong convection is within 90 nm either side of the wave axis between 15N-19N. Isolated moderate convection is within 90 nm either side of the wave axis between 14N-16N and 19N-21N. There is a medium chance of tropical formation in the next 48 hours. Interests from the islands of the northeastern Caribbean Sea to the Bahamas should continue to monitor the progress of this system. Gusty winds, heavy rains, and possible flash floods and mud slides could occur over portions of these areas regardless of tropical cyclone formation. ...TROPICAL WAVES... The tropical wave in the west Bay of Campeche has moved inland over Mexico and is no longer in the Gulf of Mexico basin. Lingering moisture over south Mexico continues to generate scattered showers and isolated thunderstorms inland and within 45 nm along the coast between 94W-96W. ...ITCZ/MONSOON TROUGH... The monsoon trough extends across Africa into the east Tropical Atlantic near 13N16W and continues to 12N28W. The ITCZ begins near 7N37W and continues along 9N51W to south America near 6N58W. The monsoon trough/ITCZ continues to be disrupted by Tropical Storm Gaston. Scattered moderate to isolated strong convection is from 8N-11N between 24W-26W. Clusters of scattered moderate convection are from 5N-8N east of 16Wn to inland over west Africa. ...DISCUSSION... GULF OF MEXICO... A broad upper ridge is anchored over the Lower Mississippi Valley covering the Gulf waters north of 26N. An elongated upper trough is centered in the west Caribbean and extends an upper trough across the Yucatan peninsula to the coast of Mexico near 24N98W. Scattered showers and Isolated thunderstorms that developed earlier in the evening over the Florida peninsula have moved into the northeast Gulf east of a line from 24N83W to the Florida/Alabama border. The highest concentration of thunderstorms are south of 26N to the Florida Keys. A surface ridge extends from over the southeast CONUS to over the Gulf. This surface ridge will persist through the end of the week. The diurnal surface trough will form each evening over the Yucatan peninsula supporting moderate to fresh winds over the east Bay of Campeche through Thursday night. CARIBBEAN SEA... The primary concern tonight is the approaching tropical wave east of the Lesser Antilles. Please see the Special Features section above. An elongated upper low is centered in the west Caribbean near 17N83W and extends an upper trough northwest across the Yucatan peninsula into the Gulf of Mexico and southeast to Colombia. Clusters of scattered showers and isolated thunderstorms are within 120 nm along the south coast of Cuba west of 75W and along the east coast of the Yucatan north of 18N. An upper ridge anchored east of the Lesser Antilles dominates the remainder of the Caribbean tonight. Scattered showers and possible isolated thunderstorms are now moving over the islands of the Lesser Antilles, Virgin Islands, and Puerto Rico ahead of the tropical wave in the Special Features above. Showers and thunderstorms that developed earlier this evening over portions of Hispaniola are now over south Haiti and into the Caribbean waters from 17N-19N between 72W- 75W. Isolated showers and thunderstorms are in the southwest Caribbean within 90/120 nm along the coast of Colombia west of 75W and within 120 nm along the coast of west Panama west of 80W. This is leaving the remainder of the basin with fair weather tonight. Fresh to strong northeast trade winds will affect the northwest coast of Colombia tonight. The Special Features low and tropical wave will track northwest and pass near the Virgin Islands tonight, then north of Puerto Rico on Wednesday, and north of Hispaniola Thursday. ...HISPANIOLA... Showers and thunderstorms that developed earlier this evening over portions of Hispaniola are now over south Haiti and into the Caribbean waters from 17N-19N between 72W-75W. Moisture with associated showers and possible thunderstorms will approach the eastern portion of the Dominican Republic early on Wednesday and spread westward throughout the day with the approaching low and tropical wave in the Special Features section above. The low is expected to track north of the island on Thursday, but could still produce gusty winds, heavy rains, and possible flash floods and mud slides over portions of the island. ATLANTIC OCEAN... The primary concern for the central Atlantic tonight is Tropical Storm Gaston and the possible development of the low and tropical wave in the Special Features section above. The upper ridge over the Gulf of Mexico extends a ridge axis across south Georgia and into the west Atlantic to 30N75W. The upper trough over the south Gulf of Mexico extends a trough axis from west Cuba across the Bahamas to 26N75W. This is creating a diffluent environment to generate scattered showers and isolated thunderstorms from Cuba to 30N west of 75W. A 1015 mb low, the remnants of Fiona, is centered near 26N66W and coupled with diffluent flow from a second upper ridge is generating scattered showers and isolated thunderstorms within 150 nm of a line from 26N67W to 31N59W. An upper low is over the central Atlantic near 27N50W generating scattered showers and isolated thunderstorms from 25N-30N between 44W-50W. The remainder of the basin east of 60W is dominated by a surface ridge anchored by a 1028 mb high near the Azores and a 1025 mb high near 33N51W. The Special Features low and tropical wave will track northwest and pass near the Virgin Islands tonight, then north of Puerto Rico on Wednesday, and north of Hispaniola Thursday with the strongest winds northeast of the low. Tropical Storm Gaston is expected to remain east of 60W as it tracks northwest. For additional information please visit http://www.hurricanes.gov/marine $$ PAW