000 AXNT20 KNHC 180554 TWDAT Tropical Weather Discussion NWS National Hurricane Center Miami FL 205 AM EDT SUN SEP 18 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 Depression Julia is centered near 30.6N 76.5W at 18/0300 UTC or about 220 nm southeast of Charleston, South Carolina moving northwest at 3 kt. Estimated minimum central pressure is 1010 mb. Maximum sustained wind speed is 25 kt with gusts to 35 kt. No associated deep convection. Scattered showers and isolated thunderstorms are within 90 nm of the center over the northeast quadrant and within 75 nm of a line from 28N75W to 33N73W. Please see the latest NHC Forecast/Advisory under the AWIPS/WMO headers MIATCMAT1/WTNT21KNHC for more details. Tropical Storm Karl is centered near 17.8N 41.3W at 18/0300 UTC or about 1175 nm east of the Leeward Islands moving west at 10 kt. Estimated minimum central pressure is 1006 mb. Maximum sustained wind speed is 35 kt with gusts to 45 kt. Clusters of scattered moderate to isolated strong convection are from 18N- 21N between 36W-42W. Please see the latest Forecast/Advisory under the AWIPS/WMO headers MIATCMAT2/WTNT22 KNHC for more details. A tropical wave located between Africa and the Capo Verde Islands extends along 21W from 9N-17N with a 1007 mb low along the wave near 15N21W. Wave and low are moving west-northwest 5 to 10 kt over the past 24 hours. Wave coincides with a global model 700 mb trough and remains embedded within a surge of moisture as shown on the Total Precipitable Water imagery. Scattered moderate to isolated strong convection is from 15N-18N between 17W-22W. Environmental conditions are expected to be conducive for development, and a tropical depression is likely to form by mid-week. Regardless of development, this system could bring rain and gusty winds to the Cabo Verde Islands during the next couple of days. This system has a medium chance of tropical formation within the next 48 hours. Please see the Tropical Weather Outlook under AWIPS/WMO Headers MIATWOAT/ABNT20 KNHC for more details. ...TROPICAL WAVES... Tropical wave approaching the Lesser Antilles in the west Tropical Atlantic extends along 60W from 11N-21N moving west 10 to 15 kt over the past 24 hours. Wave coincides with a global model 700 mb trough but remains within an area of dry air. No associated showers or deep convection. ...ITCZ/MONSOON TROUGH... Monsoon trough extends across Africa into the Tropical Atlantic near 16N16W then through the 1007 mb low in the Special Features section above, continuing along 9N28W to 11N37W. The ITCZ is being disrupted by the Tropical Storm Karl. Clusters of scattered moderate to isolated strong convection are from 8N-15N between 22W-26W and from 7N-10N between 26W-33W. Clusters of scattered moderate convection are within 90/120 nm along the coast of Africa south of 9N west of 10W. ...DISCUSSION... ...GULF OF MEXICO... An upper ridge dominates the Gulf again tonight anchored near 27N91W and extending a upper ridge axis southwest over Mexico near Tampico and northeast along the eastern seaboard into the northwest Atlantic. At the surface, a weak surface ridge extends from a 1019 mb high over western North Carolina over the northeast Gulf to 26N90W. A mid level low is centered over southeast Louisiana covering the north/central Gulf generating scattered showers and possible isolated thunderstorms north of 28N to over the north Gulf coast between 85W-87W and north of 26N to over the north Gulf coast between 87W-92W. The diurnal surface trough extends from 22N88W to inland over the Yucatan peninsula to northwest Guatemala generating scattered showers and possible isolated thunderstorms over the east Bay of Campeche south of 21N east of 93W. The mid level low will continue to bring showers and thunderstorms to the north Gulf through today. The diurnal surface trough will develop over the Yucatan peninsula each evening, moving into the southwest Gulf waters late each night, then dissipating each morning. ...CARIBBEAN SEA... A cutoff upper low is over the far northeast Caribbean near 19N86W extending an upper trough south to the coast of Honduras and north to the west tip of Cuba. This is generating isolated showers and possible isolated thunderstorms from 17N-20N west of 84W. The monsoon trough extends across the southwest Caribbean along 9N from Colombia to Panama/Costa Rica generating scattered showers and isolated thunderstorms south of 10N. An upper ridge dominates the central Caribbean anchored near 15N77W and extending an upper ridge axis through the Windward Passage. A second cutoff upper low is over the east Caribbean near 14N66W supporting a surface trough that extends along 64W from 13N-19N and generating scattered showers and isolated thunderstorms from 13N-19N between 62W-66W, including the Leeward Islands, the Virgin Islands and moving over Puerto Rico. The remainder of the Caribbean is under clear skies again tonight. Fresh to strong trade winds will develop along the coast of Colombia tonight and again Sunday night. The surface trough will continue to move west in tandem with the upper trough. A tropical wave will enter the east Caribbean tonight reaching the central Caribbean Monday. ...HISPANIOLA... Skies are clear across the island tonight. The upper low and associated surface trough over the east Caribbean will move west to over the Dominican Republic Sunday night, then across the remainder of the island by Monday night. This will bring moisture and accompanying showers and thunderstorms to the island starting Sunday night spreading west through Wednesday. ...ATLANTIC OCEAN... Primary features of concern are Tropical Storms Karl in the central Atlantic and Tropical Depression Julia off the southeast CONUS. See Special Features above. An upper trough over the west Atlantic covers the area north of 23N west of 70W while the upper ridge over the central Caribbean extends through the Windward Passage to 30N65W. To the east of the upper ridge is a surface trough that extends from 31N59W through a weak 1014 mb low near 27N64W to 22N68W. Scattered showers and isolated thunderstorms are north of 26N east of the surface trough to 54W. An upper low is centered near 23N53W generating scattered showers and isolated thunderstorms from 20N-24N between 53W-57W. The east Atlantic north of Tropical Storm Karl is dominated by a surface ridge anchored by a 1029 mb high near the Azores. Tropical Depression Julia is expected to be a remnant low later today moving slowly northward through Tuesday. Tropical Storm Karl is expected to move west through Sunday night then turn west-northwest through Tuesday. For additional information please visit http://www.hurricanes.gov/marine $$ PAW