000 AXNT20 KNHC 231151 CCA TWDAT Tropical Weather Discussion NWS National Hurricane Center Miami FL 636 AM 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 0600 UTC surface analysis and satellite imagery through 1030 UTC. ...SPECIAL FEATURES... Tropical Depression Fiona is centered near 25.8N 63.4W at 23/0900 UTC or about 456 nm north of the northern Leeward Islands, moving west-northwest at 11 kt. Estimated minimum central pressure is 1010 mb. Maximum sustained wind speed is 30 kt with gusts to 40kt. Scattered showers and isolated tstms are from 24N to 26N between 61W and 64W. Please see latest NHC Forecast/Advisory under the AWIPS/WMO headers MIATCMAT1/WTNT21 KNHC for more details. Tropical Storm Gaston is centered near 13.2N 32.4W at 23/0900 UTC or about 474 nm west of the southernmost Cabo Verde Islands, moving west at 17 kt. Estimated minimum central pressure is 1004 mb. Maximum sustained wind speed is 45 kt with gusts to 55 kt. Scattered showers are from 10N to 16N between 30W and 35W. Please see latest NHC Forecast/Advisory under the AWIPS/WMO headers MIATCMAT2/WTNT22 KNHC for more details. A tropical wave is located about 348 nm east-southeast of the Leeward Islands extending from 11N to 21N with axis near 55W. The wave is associated with a 1009 mb low located near 16N55W and has been moving west-northwest at 15-20 kt within the last 24 hours. Moisture has increased in the wave environment, which along with favorable deep layer wind shear and upper level diffluence support heavy showers and isolated tstms from 13N to 20N between 53W and 58W. Large-scale conditions could become more conducive later this week while the system moves near Hispaniola and then the southeastern and central Bahamas. Despite of any 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... A tropical wave is in the Bay of Campeche and southern Mexico. The wave extends from 11N to 21N with axis near 94W and has been moving west at 25-30 kt within the last 24 hours. Moisture associated with the wave and diffluence aloft generated by an upper level low NW of the Yucatan Peninsula support isolated heavy showers and tstms S of 23N. ...ITCZ/MONSOON TROUGH... The Monsoon Trough extends across Africa into the east Tropical Atlantic near 13N16W to 13N21W. It then resumes west of Tropical Storm Gaston near 08N33W to 08N44W to 08N50W. The ITCZ begins near 08N50W and continues to 06N57W. For convection information, see the special features and tropical waves sections. ...DISCUSSION... GULF OF MEXICO... Isolated heavy showers and tstms are in the Bay of Campeche associated with the passage of a tropical wave. The latest scatterometer show fresh to strong NE winds east of the wave axis to the Yucatan Peninsula coast. For further details see the tropical waves section. A broad surface ridge covers the eastern U.S. and extends south across the remainder Gulf of Mexico where it is anchored by a 1021 mb high near 28N86W. This ridge provides variable gentle flow to the NE basin and gentle to moderate E-SE flow elsewhere N of 21N. Except for the SW Gulf, dry air subsidence from aloft continue to support fair weather. Winds over the eastern Bay of Campeche are forecast to diminish later this morning. Mostly gentle to moderate E-SE winds are expected to prevail elsewhere through Thursday. CARIBBEAN SEA... Scattered heavy showers and tstms are over Costa Rica and Panama coastal waters. These showers are associated with the east Pacific monsoon trough. A moist airmass continues to move across Hispaniola supporting isolated showers and tstms extending to adjacent coastal waters. Unfavorable to neutral deep layer wind shear covers most of the remainder basin, which along with strong dry air subsidence from aloft support fair weather this morning. The gradient between high pressure over the Atlantic and lower pressure over northern Colombia continue to support fresh to strong winds from 10N to 14N between 74W and 80W. Moderate trade winds dominate elsewhere over the Caribbean basin. A tropical wave and associated low are located about 348 nm east-southeast of the Leeward Islands. Environmental conditions could become conducive for development of this system late this week when the system is expected to move near Hispaniola and the southeastern and central Bahamas. See the tropical waves section for further details. ...HISPANIOLA... A moist airmass is moving across Hispaniola supporting isolated showers and tstms extending to adjacent coastal waters. These showers are expected to cease later this morning, however will resume Tuesday night 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 discussed in the Special Features section above. The remainder of the area is dominated by a surface ridge anchored by two high pressure centers just N of the area. For additional information please visit http://www.hurricanes.gov/marine $$ RAMOS/ERA