000 AXNT20 KNHC 251200 TWDAT Tropical Weather Discussion NWS National Hurricane Center Miami FL 805 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 0600 UTC surface analysis and satellite imagery through 1115 UTC. ...SPECIAL FEATURES... Hurricane Gaston is centered near 19.5N 43.3W at 25/0900 UTC or about 1065 nm east of the Leeward 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-24N between 39W-45W. 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 1008 mb low north of Hispaniola near 21N68.5W. These winds are expected to continue for the next 24 hours. Scattered moderate to isolated strong convection is from 17N-21N between 66W-69W including portions of Puerto Rico and the Mona Passage, and from 17N to over Hispaniola between 69W-73W. 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 Puerto Rico, the Turks and Caicos, 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 then continues along 11N23W 7N31W to 8N37W. The ITCZ is not currently evident. The monsoon trough/ITCZ continues to be disrupted by Hurricane Gaston. Clusters of scattered moderate convection are within 60/75 nm of a line from 6N33W 5N25W 7N16W to inland over west Africa near 7N12W. ...DISCUSSION... GULF OF MEXICO... A broad upper ridge is anchored over north Mississippi covering the Gulf waters north of 24N. An elongated upper trough extends from the Yucatan peninsula near 20N91W to over Mexico just north of Tampico. The diurnal surface trough is in the east Bay of Campeche from 21N91W over Mexico to near 18N94W generating isolated showers and thunderstorms in the east Bay of Campeche south of 20N east of 95W. Clusters of scattered showers and isolated thunderstorms dot the east Gulf north of 21N east of 905 to the Florida peninsula and over the flo9rida Keys. A weak surface ridge extends from the northwest Atlantic across the southeast CONUS to over the north Gulf and is anchored by a 1024 mb high in the northwest Atlantic and a 1023 mb high over North Carolina. This surface ridge will persist through Saturday. The low in the Special Features could cause winds and seas to increase over the eastern Gulf late in the weekend to early next week. CARIBBEAN SEA... The primary concern this morning 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 north/central Caribbean. The elongated upper trough over the Gulf of Mexico extends across the Yucatan along 20N to 80W. Clusters of scattered showers and isolated thunderstorms are north of 20N to the coast of Cuba west of 80W including the Yucatan Channel, within 120 nm along the coast of Honduras between 84W-87W, and in the southwest Caribbean south of 10N between Colombia and Costa Rica. Isolated showers and possible isolated thunderstorms dot the remainder of the east Caribbean north of 13N east of 68W to over the Lesser Antilles and north of 16N between 71W-76W 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 today, 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 this morning 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 28N75W. An upper trough north of 30N is supporting a stationary front that extends through 32N67W to 27N73W continuing as a surface trough across the Bahamas to the north coast of Cuba near 23N80W. Scattered showers and isolated thunderstorms are within 60 nm of a line from 32N70W 28N76W to over Floria near 27N80W. The remnants of Fiona is now a surface trough that extends from 30N68W to 27N69W and coupled with diffluent flow from a second upper ridge to the east of the above front is generating scattered showers and possible isolated thunderstorms north of 27N between 59W-70W. An upper low is over the central Atlantic near 25N52W and is supporting a surface trough that extends from 31N49W to 25N53W. Scattered showers and isolated thunderstorms are within 90 nm either side of the surface trough. The upper trough is also generating scattered showers/isolated thunderstorms west of Hurricane Gaston within 75/90 nm of line from 25N46W to 26N48W. The remainder of the east Atlantic north of Hurricane Gaston east of 60W is dominated by a surface ridge anchored by a 1026 mb high southwest of the Azores near 36N32W and a 1024 mb high near 35N45W. 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/NAR