000 AXNT20 KNHC 160004 TWDAT Tropical Weather Discussion NWS National Hurricane Center Miami FL 804 PM EDT THU SEP 15 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 2345 UTC. ...SPECIAL FEATURES... Julia strengthened to a Tropical Storm at 2100 UTC. Its center is located near 32.1N 77.1W or about 152 nm ESE of Charleston South Carolina moving E at 7 kt. Estimated minimum central pressure is 1007 mb. Maximum sustained wind speed is 35 kt with gusts to 45 kt. Scattered moderate convection and isolated tstms are from 30N to 34N between 70W and 77W. See latest NHC forecast/advisory under AWIPS/WMO headers MIATCMAT1/WTNT21 KNHC for more details. Tropical Storm Ian is centered near 39.6N 47.7W at 15/2100 UTC or about 938 nm ENE of Bermuda moving NE at 30 kt. Estimated minimum central pressure is 998 mb. Maximum sustained wind speed is 45 kt with gusts to 55 kt. Scattered moderate convection is N of 39N between 40W and 50W. See latest NHC forecast/advisory under AWIPS/WMO headers MIATCMAT5/WTNT25 KNHC for more details. Tropical Depression Twelve is centered near 17.8N 31.4W at 15/2100 UTC or about 439 nm WNW of the Cabo Verde Islands moving W at 11 kt. Estimated minimum central pressure is 1008 mb. Maximum sustained wind speed is 30 kt with gusts to 40 kt. A cluster of heavy showers and tstms is from 17N to 20N between 27W and 31W. See latest NHC forecast/advisory under AWIPS/WMO headers MIATCMAT2/WTNT22 KNHC for more details. ...TROPICAL WAVES... A tropical wave is in the central Atlantic extending from 10N to 19N with axis near 48W moving W at 10 kt within the last 24 hours. Even though the wave is in a region of favorable deep layer wind shear, water vapor imagery show strong dry air subsidence that along with Saharan dry air and dust in the wave environment hinder convection at the time. ...ITCZ/MONSOON TROUGH... The Monsoon Trough extends from the African coast near 09N13W to 07N20W and then from 13N35W to 10N50W. The Intertropical Convergence Zone axis extends from 10N50W to 08N58W. Aside from convection associated with Tropical Depression Twelve...scattered heavy showers and isolated tstms are from 08N to 11N E of 16W. ...DISCUSSION... GULF OF MEXICO... Low pressure dominates at the surface across most of the basin. At 2100 UTC, a 1011 mb low is in the NW Gulf near 27N95W from which a surface trough extends NE to 29N91W then E along 28N85W to the northern Florida Peninsula near 29N81W. This area of low pressure is beneath a broad upper level anticyclone, which divergent flow support scattered showers from 24N to 29N between 87W and 95W and isolated showers within 60 nm either side of the remainder trough axis. There is a low chance of this system to develop within the next two days. Development of this system, if any, should be slow to occur before it moves inland over Texas by Saturday. Otherwise, isolated showers are across the Bay of Campeche associated with a surface trough extending from 22N94W to 18N95W. Thereafter...gentle to moderate E-SE winds are anticipated through the upcoming weekend as a surface ridge re-establishes itself across the SE CONUS. CARIBBEAN SEA... A broad upper level low continues to cover the NW Caribbean waters supporting scattered showers and isolated tstms along the southern coastline of Cuba and adjacent waters. Isolated showers extends to the Windward Passage, Haiti and the Cayman trench. In the SW basin, a 1011 mb low near 10N77W and diffluent flow aloft support heavy showers and isolated