000 AXNT20 KNHC 121730 TWDAT Tropical Weather Discussion NWS National Hurricane Center Miami FL 130 PM EDT MON SEP 12 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 1200 UTC surface analysis and satellite imagery through 1730 UTC. ...SPECIAL FEATURES... As of 09/1500 UTC, the 1007 mb surface low and tropical wave analyzed over the central Atlantic near 50W are now T.S. Ian, centered near 21.8N/50.4W. Ian is moving northwest at around 11 kt. Minimum central pressure is 1007 mb and maximum sustained winds are 35 kt with gusts to 45 kt. Scattered moderate convection is from 20N-28N between 45W-51W. For more details, please see the latest NHC forecast/advisory under AWIPS/WMO headers MIATCMAT5/WTNT25 KNHC for more details. ...TROPICAL WAVES... A tropical wave moving across the eastern Atlantic with axis extending from 16N21W to 04N21W, moving west at around 10-15 kt within the past 24 hours. The wave is embedded in an area of abundant moisture as depicted in TPW imagery. Scattered moderate convection is observed from 09N19N between 17W-27W. A tropical wave is moving across the central Atlantic with axis from 15N31W to 04N32W, moving west at around 10-15 kt during the past 24 hours. The wave is ahead of a surge of moisture as noted in TPW imagery. No significant convection is related to this feature at this time. A tropical wave is moving across the western Caribbean and Central America wit axis extending from 20N87W to 12N87W, moving west near 05-10 kt during the past 24 hours. A 700 mb inverted trough is noted in model guidance with this feature. Isolated moderate convection is observed along the northern portion of the wave north of 17N between 85W-88W. ...ITCZ/MONSOON TROUGH... The Monsoon Trough extends across western Africa reaching the eastern Atlantic near 15N17W to 11N24W to 09N35W. Aside from the convection related to the tropical wave along 21W, isolated moderate convection is from 07N-10N between 24W-28W and from 05N-08N between 33W-40W. ...DISCUSSION... GULF OF MEXICO... An upper-level trough covers the basin with axis along 88W. A diffluent flow prevails over the eastern Gulf waters supporting scattered moderate convection mainly east of 89W. At the surface; a weak 1013 mb low is centered north of the Yucatan Peninsula near 24N87W. To the north; a surface trough extends from 28N86W to 30N83W. Scatterometer data depicts a gentle to moderate easterly flow across the basin. During the next 24 hours, the upper-level trough will move eastward enhancing convection across the Florida Peninsula and western Atlantic. The surface low will dissipate. CARIBBEAN SEA... The northern portion of a tropical wave extends across the western Caribbean. Please refer to the section above for details. A diffluent flow aloft is enhancing scattered moderate convection across the western portion of the basin mainly west of 80W. To the south; the Monsoon Trough extends along 11N enhancing convection south of 13N between 74W-84W. Fair weather prevails east of 74W. Scatterometer data depicts moderate to fresh trades across the whole area. Expect during the next 24 hours for the wave in the western Caribbean to continue moving west away from the area. Convection will prevail west of 80W. ...HISPANIOLA... Fair weather prevails across the island at this time. Scattered showers and possibly a few thunderstorms are expected in the afternoon hours due to daytime heating, orographic lifting, and abundant low-level moisture. ATLANTIC OCEAN... T.S. Ian has developed in the central Atlantic while two tropical waves are moving over the eastern portion of the area. Please refer to the sections above for details. A surface trough extends across the western Atlantic from 29N75W to 23N77W supporting scattered moderate convection between 74W-79W. The remainder of the basin is dominated by a surface ridge, anchored by three high centers located near 33N73W, 32N55W, and 31N40W. Expect during the next 24 hours for convection to continue across the western Atlantic. T.S Ian will move northwest enhancing winds/seas. The tropical waves will continue moving west with convection. For additional information please visit http://www.hurricanes.gov/marine $$ ERA