000 AXNT20 KNHC 131030 TWDAT Tropical Weather Discussion NWS National Hurricane Center Miami FL 630 AM EDT Sun Aug 13 2017 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 Eight was centered near 26.5N 70.9W at 13/0900 UTC with maximum sustained winds of 30 kt gusting to 40 kt and a minimum sea level pressure of 1011 mb. The depression is moving toward the north-northwest, or 335 degrees, at 12 kt. Numerous moderate and scattered strong convection is noted within 120 nm southeastern semicircle of the low. The system is expected to remain east of the United States, moving in a north- northwestward direction today as it reaches tropical storm intensity, then remaining at tropical storm intensity while moving northward tonight, then northeastward by Monday night. See latest NHC forecast/ advisory under AWIPS/WMO headers MIATCMAT3/WTNT23 KNHC for more details. ...TROPICAL WAVES... The axis of a tropical wave is near 32W from 07N to 21N, moving W at 15-20 kt. This wave is very evident in low-mid level satellite cloud wind vectors. Scattered moderate convection is noted from 07N- 14N between 30W- 37W. The axis of a tropical wave is near 52W from 05N to 21N. The wave is moving W at 15-20 kt. There is limited convection associated to this wave. The axis of a tropical wave in the western Caribbean is near 83W from 06N to 22N. The wave is moving W at 20 kt. Scattered moderate to isolated strong convection is over the SW Caribbean south of 14N and west of 75W. ...ITCZ/MONSOON TROUGH... The monsoon trough extends from the coast of African near 19N16W to 13N22W to 09N45W. The Intertropical Convergence Zone continues from 09N45W to 08.5N50W. It resumes from 08N53W to the coast of South America near 07.5N58.5W. Aside from convection associated with the tropical waves, scattered moderate isolated strong convection is noted from 10N- 15N between 17W- 25W. This convection is ahead of the next tropical wave which is just moving off the coast of Africa. ...DISCUSSION... GULF OF MEXICO... A ridge of high pressure prevails over the Gulf of Mexico with light to gentle anticyclonic flow covering much of the Gulf waters. The one exception is an area of moderate winds west of a thermal trough that moved off the Yucatan Peninsula into the southwest Gulf. The ridge will remain across the Gulf waters the next several days. Southerly return flow will freshen over western Gulf by midweek. A thermal trough will develop each evening over the Yucatan Peninsula, shifting westward into the southwest Gulf during the overnight hours, and dissipating over this area each morning. Locally higher winds can be expected west of the trough axis. CARIBBEAN SEA... Please see above for more on the tropical wave moving through the western Caribbean. The tropical wave will continue to propagate westward, moving west of the area late tonight. Fresh to strong winds prevail over the south central Caribbean, gentle to moderate winds are noted over the western Caribbean, and moderate to fresh winds prevail elsewhere. These general conditions will continue across the Caribbean through midweek. Ample moisture associated to a tropical wave is helping produce active convection over the southwest Caribbean as well as the surrounding land masses. ...HISPANIOLA... Moisture will decrease across the area today. Expect isolated showers and tstms today due to daytime heating, local sea breezes and mountain upslope lifting. ATLANTIC OCEAN... Please see the special features section above for more on Tropical Depression Eight and the tropical wave section above for more on the tropical waves propagating across the tropical Atlantic waters. Outside of Tropical Depression Eight, gentle to moderate winds prevail across much of the area, except freshening winds noted between the eastern tropical wave and strengthening subtropical high to the north. The fresh winds will shift along with the tropical wave as it propagates westward the next couple of days. For additional information please visit http://www.hurricanes.gov/marine $$ AL