628 AXNT20 KNHC 170517 CCA TWDAT Tropical Weather Discussion...Corrected NWS National Hurricane Center Miami FL 805 PM EDT Sun Sep 16 2018 Corrected Special Features section 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...Corrected Tropical Depression Joyce is centered near 34.4N 32.6W at 16/2100 UTC or 350 nm SW of the Azores moving E at 15 kt. Estimated minimum central pressure is 1008 mb. Maximum sustained wind speed is 30 kt with gusts to 40 kt. Latest satellite imagery shows that Joyce is a sheared system as noted by its deep convection being sheared off to the northeast of its the center. The convection is defined as the moderate type intensity within 30 nm either side of a line from 37N27W to 36N30W to 26N31W. Overcast to broken low and mid-level clouds with embedded scattered showers and isolated thunderstorms are well to the east and northeast of Joyce from 34N to 38N between 21W and 27W. Strong southwest to west winds aloft and dry air in its surrounding environment will continue to hamper Joyce over the next few days causing it to gradually weaken. Joyce will continue on its present motion through tonight, then it is forecast to slow down and turn toward the southeast and then the southwest away from the Azores. See the latest NHC forecast/advisory under AWIPS/WMO headers MIATCPAT5/WTNT35 KNHC for more details. ...TROPICAL WAVES... A central Atlantic tropical wave has its axis extending along 40W between 05N and 20N, moving westward near 15 kt. The wave is supported by broad troughing at the 700 mb level. Earlier dust that surrounded the wave has thinned out since yesterday as a surge of low-level moisture is presently surging westward on either side of the wave south of the wave axis. This moisture has lead to scattered showers and thunderstorms moving quickly westward from 10N to 12N between 34W and 38W, and from 11N to 14N within 120 nm west of the wave axis. Similar activity is within 60 nm either side of the wave in the vicinity of the ITCZ region from 05N to 08N. ...MONSOON TROUGH/ITCZ... The monsoon trough axis extends from well inland Africa southwestward to the coastline near 16N16W and continues to 09N22W. The ITCZ extends from 09N22W to 06N30W to just west of the tropical wave along 40W. It resumes at 08N41W to 07N49W to 06.5N54.5W to 07N59W. Aside from the shower and thunderstorms activity associated with the tropical wave described above, scattered moderate isolated strong convection is within 240 nm north of the ITCZ between 51W and 59W, and within 150 nm south of the ITCZ between 42W and 48W. Scattered moderate convection is within 150 nm north of the ITCZ between 48W and 51W. ...DISCUSSION... GULF OF MEXICO... In the upper-levels, and elongated upper low is over the western gulf near 25N93W, with a trough extending northeastward to southern Mississippi, and another trough from the low to the eastern Bay of Campeche. Upper-level cyclonic flow covers the basin west of 86W. Anticyclonic flow aloft associated with an upper-level anticyclone over the northwestern Caribbean near 20N84W is over the gulf east of 86W. At the surface, a trough is just inland the coast of Mexico from 20N to near San Fernando. Plenty of atmospheric instability along with deep moisture in place is leading to scattered showers and isolated thunderstorms south of 25N and west of 94W to inland Mexico, where the activity increases to scattered in coverage. At the surface, high pressure of 1015 mb is centered near 27N93W. Relatively weak high pressure is across the basin. A surface trough extends southwestward from what is now Tropical Depression Florence located over the border of eastern Georgia, southwestward to over the Florida Panhandle. Scatterometer data from this afternoon highlighted light to gentle anticyclonic flow west of 87W, and light to moderate south to southwest flow east of 87W. Little change in these winds is expected through the middle part of the upcoming week. CARIBBEAN SEA... A surface trough extends across the central Caribbean from just west of Haiti to a 1009 mb low at 17N75W to near 11N77W. Abundant moisture prevails in this area is supporting scattered moderate to strong convection from 15N to 18N between 73W and 76W. These features and related convection denote a broad area of low pressure associated with former tropical cyclone Isaac. This area of low pressure remains disorganized.Only slow development will be possible during the next day or so due to proximity to dry air and land interaction with Jamaica. By Wed, environmental conditions are forecast to become less conducive for re- development to occur. Regardless of development, locally heavy rains and gusty winds will be possible over portions of Hispaniola, Jamaica, and eastern Cuba during the next couple of days while the system moves west-northwestward to westward toward the northwestern Caribbean Sea. Latest scatterometer data depicted gentle trades west of the trough, while gentle to moderate trades are elsewhere east of the trough. The central Atlantic tropical wave will move across the tropical waters east of the Windward Islands by Tue, accompanied by fresh winds and building seas. ATLANTIC OCEAN... Please refer to the Special Features section above, for details on now Tropical Depression Joyce. A broad deep-layer trough extends across the central Atlantic from a large and elongated upper-level low that is north of the area near 35N52W southwestward to 20N69W. Plenty of instability exists with this trough as it acts on a very moist atmosphere. The trough is forecast to move westward during the next few days. At the surface, a 1012 mb low is near 24N65W, with a trough from 28N60W to 24N66W. To the east, another trough extends from 27N55W to 22N60W. Scattered moderate convection is noted with these features between 52W and 66W. Surface ridging prevails across the remainder of the basin, anchored by a 1022 mb high centered near 26N34W. An area of African dust is over the eastern Atlantic from 10N to 25N east of 37W, and is gradually migrating westward. For additional information please visit http://www.hurricanes.gov/marine $$ Aguirre