000 AXNT20 KNHC 230607 TWDAT Tropical Weather Discussion NWS National Hurricane Center Miami FL 207 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 0000 UTC surface analysis and satellite imagery through 0545 UTC. ...SPECIAL FEATURES... Tropical Depression Fiona is centered near 25.5N 62.3W at 23/0300 UTC or about 439 nm north of the northern Leeward Islands, moving west-northwest at 13 kt. Estimated minimum central pressure is 1010 mb. Maximum sustained wind speed is 30 kt with gusts to 40kt. Scattered heavy showers and tstms are from 23N to 25N between 60W and 63W. Please see latest NHC Forecast/Advisory under the AWIPS/WMO headers MIATCMAT1/WTNT21 KNHC for more details. Tropical Storm Gaston formed near 0300 UTC. Its center is near 12.6N 30.7W or about 391 nm west-southwest of the southernmost Cabo Verde Islands, moving west at 16 kt. Estimated minimum central pressure is 1005 mb. Maximum sustained wind speed is 35 kt with gusts to 45 kt. Scattered heavy showers are from 10N to 16N between 27W and 34W. Please see latest NHC Forecast/Advisory under the AWIPS/WMO headers MIATCMAT2/WTNT22 KNHC for more details. ...TROPICAL WAVES... A tropical wave is located about 478 nm east of the Lesser Antilles extending from 09N to 20N with axis near 53W. The wave is associated with a 1012 mb low located near 16N53W and has been moving west 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 scattered showers and isolated tstms from 14N to 19N between 51W and 56W. Conditions are marginally conducive for some gradual development during the next few days while the disturbance moves westward to west- northwestward. Environmental conditions could become more conducive for development late this week when the system is expected to move near Hispaniola and the southeastern and central Bahamas. A tropical wave is in the Bay of Campeche and southern Mexico. The wave extends from 10N to 21N with axis near 92W 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 N of the Yucatan Peninsula support scattered heavy showers and isolated tstms from 19N-21N east of 95W. ...ITCZ/MONSOON TROUGH... The Monsoon Trough extends across Africa into the east Tropical Atlantic near 14N17W to 13N25W. It then resumes west of Tropical Storm Gaston near 08N34W to 10N47W. The ITCZ begins near 07N53W and continues to 07N58W. For convection information, see the special features and tropical waves sections. ...DISCUSSION... GULF OF MEXICO... Sacattered heavy showers and isolated tstms are in the Bay of Campeche associated with a tropical wave that move off the Yucatan Peninsula earlier tonight. The latest scatterometer show fresh to strong NE winds within 190 nm off the western Yucatan Peninsula coast associated with the passage of this wave. 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 27N86W. 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 near sunrise today. Mostly gentle to moderate E-SE winds are expected to prevail elsewhere through Thursday. CARIBBEAN SEA... Scattered heavy showers and tstms are along Costa Rica and southern Panama extending about 90 nm off its coasts. These showers are associated with the east Pacific monsoon trough. A moist airmass is moving across Hispaniola supporting isolated showers and tstms mainly over southern Haiti and adjacent 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 tonight. The gradient between high pressure over the Atlantic and lower pressure over northern Colombia continue to support fresh to strong winds S of 16N between 68W and 82W. Moderate trade winds dominate elsewhere over the Caribbean basin. A tropical wave and associated low are located about 478 nm east of the Lesser Antilles. 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 mainly over southern Haiti and adjacent waters. These showers are expected to cease after sunrise today, however will resume Tuesday night as another moist airmass moves across the Island. ATLANTIC OCEAN... The main features of interest in the basin tonight are Tropical Storm Gaston and Tropical Depression Fiona discussed in special features. There is a tropical wave east of the Lesser Antilles, however, conditions are marginally conducive for some gradual development during the next few days while the disturbance moves westward to west-northwestward. See the tropical waves section for more details. The remainder of the area is dominated by a surface ridge anchored by several high centers N of the area. For additional information please visit http://www.hurricanes.gov/marine $$ RAMOS