000 AXNT20 KNHC 252341 TWDAT Tropical Weather Discussion NWS National Hurricane Center Miami FL 741 PM 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 1800 UTC surface analysis and satellite imagery through 2315 UTC. ...SPECIAL FEATURES... Tropical Storm Gaston is centered near 21.6N 45.5W at 25/2100 UTC or about 960 nm ENE of the Leeward Islands moving NW at 15 kt. Estimated minimum central pressure is 994 mb. Maximum sustained wind speed is 55 kt with gusts to 65 kt. Scattered moderate and isolated strong convection is from 21N-24N between 44W-46W. Scattered moderate convection is elsewhere from 19N-27N between 40W-52W. See latest NHC Forecast/Advisory under the AWIPS/WMO headers MIATCMAT2/WTNT22 KNHC for more details. ...TROPICAL WAVES... Tropical wave extends from 10N20W to 19N20W moving W at 10-15 kt. The wave emerged off the African coast last evening and continues to exhibit a low-level cyclonic circulation focused in the vicinity of a 1008 mb low along the wave axis near 14N. Isolated moderate convection is from 06N-10N between 11W-17W. ...ITCZ/MONSOON TROUGH... The Monsoon Trough extends from 13N20W to 07N32W to 09N42W. The Intertropical Convergence Zone axis extends from 12N47W to 11N60W. Isolated moderate convection is from 03N-05N between 27W-35W. ...DISCUSSION... GULF OF MEXICO... An upper level anticyclonic circulation is centered over the Tennessee River valley near 36N84W providing much of the Gulf basin with E-SE flow aloft. At the surface...the upper level ridging supports a ridge anchored by a 1021 mb high centered across northern Georgia with axis extending W-SW to southern Texas near Corpus Christi. Generally gentle to moderate NE to E winds are noted at this time and are expected to persist through Saturday. Otherwise...afternoon convection is ongoing across the SE and north-central portions of the basin with scattered showers and tstms occurring S of 27N E of 89W...and N of 25N between 89W-95W. Another area of isolated showers and tstms is noted across the SW Gulf waters in association with a weak surface trough analyzed from 22N94W to 18N94W. CARIBBEAN SEA... The primary concern for the Caribbean is a broad area of low pressure NW of Hispaniola this evening. As the area tracks W-NW during the next 24-36 hours...plenty of precipitation is expected across Hispaniola...the Windward Passage...portions of eastern Cuba with localized flooding and mud slides possible. Otherwise...convection associated with the low is enhanced due to an upper level anticyclonic circulation centered over the north- central Caribbean near 18N70W. Farther west...drier air is noted on water vapor imagery with most of the western Caribbean experiencing clear skies and fair weather this evening. Only a few isolated showers and tstms are occurring W of 86W...including the Gulf of Honduras and inland portions of Belize...Guatemala...and the Yucatan peninsula. Although the trades are disrupted slightly due to the low pressure area mentioned above...overall E to NE winds remain within moderate to occasional fresh breeze levels S of 16N between 65W-76W. ...HISPANIOLA... Scattered showers and tstms associated with the broad low pressure area NW of the island are expected to persist through the overnight period into Friday as the low moves W-NW during the next 24-36 hours. Gusty winds...heavy rainfall...flash flooding...and mud slides are possible across the island through Saturday. ATLANTIC OCEAN... Aside from Tropical Storm Gaston...a 1008 mb low is centered N of Hispaniola near 21N72W moving W-NW at 15-20 kt. Low-level streamline analysis indicates surface troughing extending from N of Bermuda through the remnant low of Fiona near 29N69W to the broad area of low pressure across the central Caribbean Sea. Visible satellite imagery shows an exposed low-level circulation center with most of the active convection noted across Hispaniola...and the adjacent coastal waters around Hispaniola and Jamaica. Scattered moderate convection is from 16N-24N between 65W-70W...and from 17N-21N between 70W-78W. In addition...an upper level trough is noted on water vapor imagery with axis extending from 35N65W W-SW to 30N79W. This troughing supports a dissipating stationary front analyzed from 32N66W SW into a 1014 mb low...the remnants of Fiona...to 28N71W. Scattered showers and tstms are occurring N of 27N between 58W and the frontal boundary to the west. Furthermore...a surface trough is analyzed from 25N78W to 28N75W and is providing focus for scattered showers and tstms generally N of 24N W of 73W...including inland portions of the southern Florida peninsula. Farther east...an upper level low is centered over the central Atlc near 23N53W and supports a surface trough analyzed from 26N56W to 31N52W. Within the eastern periphery of the upper level low...maximum upper level diffluence is noted on water vapor imagery supporting a portion of the convection NW of Gaston. Otherwise...the remainder of the eastern Atlc is under the influence of a surface ridge anchored by a pair of 1024 mb highs...one centered near 33N39W and the other centered near 38N25W. For additional information please visit http://www.hurricanes.gov/marine $$ HUFFMAN