000 AXNT20 KNHC 250553 TWDAT Tropical Weather Discussion NWS National Hurricane Center Miami FL 205 AM EDT THU AUG 25 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 was upgraded to a hurricane at 25/0415 UTC. Hurricane Gaston is centered near 18.7N 42.2W at 25/0415 UTC or about 1055 nm west of the Cabo Verde Islands moving northwest at 15 kt. Estimated minimum central pressure is 988 mb. Maximum sustained wind speed is 65 kt with gusts to 80 kt. Scattered moderate to isolated strong convection is from 18N-22N between 39W-43W. 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. ...Gale Warning for Southwest Atlantic... A Gale warning has been issued for the area northeast of a broad area of low pressure analyzed as a 1009 mb low north of Puerto Rico/Mona Passage near 20N67W. These winds are expected to continue for the next 48 hours. Scattered to numerous strong convection is redeveloping near the low center from 18.5N-20.5N between 65W-68W including the north coast of Puerto Rico. scattered showers and isolated thunderstorms dot the area from 20N to over Puerto Rico, the Virgin islands, and the Mona Passage between 63W-69W; from 17N-21N between the 69W-73W including portions of Hispaniola. Environmental conditions have the potential to become more conducive for tropical development over the weekend when the system is near the central or northwestern Bahamas. Regardless of development, gusty winds, heavy rains, and possible flash floods and mudslides are likely to occur over portions of the Leeward Islands, Puerto Rico, Hispaniola, and the southeastern and central Bahamas during the next couple of days. There is a medium chance of tropical development in the next 48 hours. ...TROPICAL WAVES... None. ...ITCZ/MONSOON TROUGH... The monsoon trough extends across Africa into the east Tropical Atlantic near 18N16W through a weak 1009 mb low near 16N18W then continues along 12N23W to 12N35W. The ITCZ is not currently evident. The monsoon trough/ITCZ continues to be disrupted by Tropical Storm Gaston. No associated showers or deep convection is noted. ...DISCUSSION... GULF OF MEXICO... A broad upper ridge is anchored over the central Mississippi covering the Gulf waters north of 24N. An elongated upper trough extends from the Yucatan peninsula near 19N91W to over Mexico near Tampico. The diurnal surface trough has moved off the west coast of the Yucatan at 25/0300 UTC from 21N91W over Mexico to near 17N92W generating scattered showers and thunderstorms in the east Bay of Campeche south of 21N east of 92W. Isolated showers and thunderstorms dot the east Gulf from 22N-28N east of 90W to the Florida peninsula and in the coastal waters of southeast Louisiana. The west Gulf is under mostly clear skies tonight. A weak surface ridge extends from the northwest Atlantic across the far southeast CONUS to over the north Gulf and is anchored by a 1026 mb high in the northwest Atlantic. This surface ridge will persist through Saturday night. The low in the Special Features could cause winds and seas to increase over the northeastern Gulf on Sunday into early next week. CARIBBEAN SEA... The primary concern tonight is the low in the Special Features moving just north of the Greater Antilles. Please see the Special Features section above for the activity associated with this system over the northeast Caribbean. The elongated upper trough over the Gulf of Mexico extends across the Yucatan along 19N to 81W. Clusters of scattered showers and isolated thunderstorms are within 90 nm along the south coast of Cuba between 76W-85W and in the southwest Caribbean south of 10N between Colombia and Costa Rica. Isolated showers and possible isolated thunderstorms cover the remainder of the east Caribbean north of 12N east of 70W to over the Lesser Antilles associated with the low in the Special Features. The low in the Special Features will continue to track northwestward. The strongest winds are found northeast of the low. ...HISPANIOLA... Currently scattered showers and isolated thunderstorms are over portions of the island due to the low in the Special Features. Please see the Special Features section above. The low is expected to move northwestward north of the island through early Friday, but could still produce gusty winds, heavy rains, and possible flash floods and mud slides over portions of the island during the next couple of days. ATLANTIC OCEAN... The primary concern tonight is the low in the Special Features moving just north of the Greater Antilles. Please see the Special Features section above for the activity associated with this system over the southwest Atlantic. The upper ridge over the Gulf of Mexico extends a ridge axis across south Georgia into the west Atlantic to near 28N73W. An upper trough north of 30N is supporting a stationary front that extends through 32N66W to 28N74W continuing as a surface trough into the Straits of Florida near near 24N82W. Scattered showers and isolated thunderstorms are within 120 nm either side of the front and trough. A 1016 mb low, the remnants of Fiona, is centered just south of the front near 29N68W and coupled with diffluent flow from a second upper ridge to the east of the front is generating scattered showers and isolated thunderstorms north of 27N west of 59W to the front. An upper low is over the central Atlantic near 25N52W and is supporting a surface trough that extends from 31N45W along 29N50W to 26N52W. Scattered showers and isolated thunderstorms are within 120 nm west of the surface trough. The remainder of the east Atlantic north of Hurricane Gaston east of 60W is dominated by a surface ridge anchored by a 1027 mb high southwest of the Azores near 36N32W and a 1026 mb high near 34N44W. The Special Features low will track northwestward through the Bahamas into the weekend with gale force winds northeast of the surface low. For additional information please visit http://www.hurricanes.gov/marine $$ PAW