000 AXNT20 KNHC 231745 TWDAT Tropical Weather Discussion NWS National Hurricane Center Miami FL 145 PM EDT TUE AUG 23 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 1200 UTC surface analysis and satellite imagery through 1730 UTC. ...SPECIAL FEATURES... Tropical Depression Fiona is centered near 25.8N 63.4W at 23/1500 UTC or about 374 nm south of Bermuda, moving west- northwest at 10 kt. Estimated minimum central pressure is 1014 mb. Maximum sustained wind speed is 25 kt with gusts to 35kt. Isolated showers are observed from 24N-28N between 62W-66W. Please see latest NHC Forecast/Advisory under the AWIPS/WMO headers MIATCMAT1/WTNT21 KNHC for more details. Tropical Storm Gaston is centered near 13.8N 34.6W at 23/0900 UTC or about 595 nm west of the southernmost Cabo Verde Islands, moving west-northwest at 18 kt. Estimated minimum central pressure is 1002 mb. Maximum sustained wind speed is 55 kt with gusts to 65 kt. Scattered showers are from 11N-16N between 33W-37W. Please see latest NHC Forecast/Advisory under the AWIPS/WMO headers MIATCMAT2/WTNT22 KNHC for more details. A tropical wave is located at about 300 nm east of the Leeward Islands extending its axis from 20N57W to a 1009 mb low near 17N56W to 12N55W, moving west-northwest at 15-20 kt within the last 24 hours. Moisture continues to increase in the wave's environment, which combined with upper-level diffluence support scattered to numerous moderate convection from 12N-21N between 54W-60W. Large-scale conditions could become more conducive for tropical development later this week while the system moves near Hispaniola and then the southeastern and central Bahamas. Interests from the islands of the northeastern Caribbean Sea to the Bahamas should monitor the progress of this system. Despite of the tropical development, gusty winds, heavy rains, and possible flash floods and mud slides could occur over these areas. This system has a medium chance for tropical formation within the next 48 hours. ...TROPICAL WAVES... The northern portion of a tropical wave extends across the Bay of Campeche and southern Mexico. The wave axis is from 21N94W to 11N94W and has been moving west at 15-20 kt within the last 24 hours. Moisture associated with the wave combined with a diffluent flow is generating scattered moderate convection south of of 22N between 92W-97W. ...ITCZ/MONSOON TROUGH... The Monsoon Trough extends across Africa into the east Tropical Atlantic near 13N17W to 12N22W. This boundary resumes south of Tropical Storm Gaston near 10N32W to 10N50W. No significant convection is related to these boundaries at this time. ...DISCUSSION... GULF OF MEXICO... The northern portion of a tropical wave is moving across the Bay of Campeche. Please refer to the section above for details. The remainder of the basin is under the influence of a surface ridge anchored by a 1023 mb high centered near 29N87W. Latest scatterometer data depicts moderate to fresh easterly winds over the southwest Gulf mainly south of 23N and west of 90W. A gentle to moderate anticyclonic flow prevails elsewhere. Expect for winds to subside across the Bay of Campeche as the tropical wave moves west within the next 24 hours. Surface ridging will prevail across the remainder of the basin. CARIBBEAN SEA... The proximity of the Monsoon Trough currently extending across southern Panama is supporting scattered moderate convection over the southern Caribbean mainly south of 12N between 80W-84W. A diffluent flow aloft is supporting isolated moderate convection across the adjacent waters of Cuba, Jamaica, and Hispaniola north of 18N between 71W-78W. The pressure gradient between the high pressure over the Atlantic and lower pressure over northern Colombia continue to support fresh to strong winds from 10N-14N between 68W-78W. Moderate trades dominate the remainder of the basin. Expect during the next 24-48 hours for a strong tropical wave to enter the eastern Caribbean with abundant convection. Environmental conditions could become conducive for tropical development of this system late this week when it moves near Hispaniola and then shift northwest reaching the southeastern and central Bahamas. Please the Special Features section above for further details. ...HISPANIOLA... A diffluent flow aloft combined with low level moisture are supporting isolated convection across the adjacent coastal waters. These showers are expected to cease later later today, however, will resume by tonight as another moist airmass moves across the island. ATLANTIC OCEAN... The main features of interest in the basin continue to be Tropical Storm Gaston, Tropical Depression Fiona and the tropical wave along 57W. All these features are discussed in the Special Features section above. Scattered moderate convection is observed across the western Atlantic at this time supported by a diffluent flow aloft. This activity prevails north of 26N and west of 75W. The remainder of the area is dominated by a surface ridge anchored by two high pressure centers located just N of our area of discussion. For additional information please visit http://www.hurricanes.gov/marine $$ ERA