000 AXNT20 KNHC 201716 TWDAT Tropical Weather Discussion NWS National Hurricane Center Miami FL 116 PM EDT Sun May 20 2018 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 1715 UTC. ...SPECIAL FEATURES... An upper-level trough extends across the eastern Gulf of Mexico and western Caribbean, with diffluent flow aloft prevailing across the Florida Peninsula and the western Atlantic and Caribbean, to the east of the upper trough's axis. This pattern is drawing deep tropical moisture northward from the SW Caribbean between 77W and 82W and is supporting scattered to numerous moderate convection along this corridor. This activity is expected to continue through early this upcoming week, with heavy rainfall and flooding possible over the land areas affected. ...TROPICAL WAVES... A tropical wave has an axis that extends from 13N29W to 01N29W, moving W at around 15 kt. This wave is embedded in a sharp 700 mb trough and scattered convection south of 3N. A central Atlantic tropical wave has an axis that extends from 14N56W to 05N57W, moving W at 5 to 10 kt. This wave has slowed down its forward motion over the past 24 hours and is expected to become diffuse east of the Caribbean over the next couple of days. No significant convection is related to this wave at this time. ...MONSOON TROUGH/ITCZ... The monsoon trough passes through the coastal Africa near 14N17W to 03N27W. The ITCZ extends west of a tropical wave from 02N33W to 04N51W. Besides the convection associated with the wave, scattered moderate convection is noted along the ITCZ. ...DISCUSSION GULF OF MEXICO... An upper-level trough prevails across the eastern Gulf, with an axis along 85W. Diffluent flow aloft east of the trough is bringing tropical moisture over the far east Gulf and western Atlantic waters affecting the Florida Peninsula and Florida Straits/Keys. Please refer to the Special Features section above for more details. A surface trough is embedded within this convection, extending across central Florida and adjacent waters. A weak ridge axis extends across the remainder of the basin along 30N producing mainly gentle to moderate winds. The surface trough is expected move into the eastern Gulf through Monday. The upper-level trough over the eastern Gulf will remain nearly stationary through the first half of this upcoming week, supporting ongoing convection over the eastern Gulf. CARIBBEAN SEA... An upper-level trough extends over the eastern Gulf of Mexico and western Caribbean. An overnight scatterometer pass indicated that a surface trough has developed over the northwest Caribbean, with axis extending from 23N81W to 19N83W. The combination of upper- level diffluence on the eastern side of the upper-level trough and convergence associated with the surface trough is supporting scattered to numerous moderate convection across the Caribbean waters between 78W and 83W. Broad high pressure over the subtropical Atlantic continues to support moderate to fresh tradewinds over most of the basin, except fresh to strong winds over the central Caribbean. Wave heights of 8 to 10 ft persist over the central Caribbean as confirmed by a recent satellite altimeter pass and current buoy data. Over the next couple of days, the upper-level trough will remain in place enhancing shower and thunderstorm activity over the western Caribbean. The surface ridging pattern over the Atlantic will persist, keeping a similar wind profile in place across the basin into the middle of this upcoming week. ATLANTIC OCEAN... Diffluent flow aloft to the east of an upper-level trough currently over the eastern Gulf of Mexico, combined with a surface trough extending just offshore of northern Florida is supporting scattered to numerous moderate convection across Florida, the Bahamas, and Atlantic waters mainly west of 76W. To the east, high pressure centered over the central Atlantic spans across the basin. Surface observations and latest scatterometer data indicate prevailing fresh to locally strong southeast winds over a portion of the Bahamas as well as within a few hundred miles north of Hispaniola. A recent altimeter pass indicates wave heights of 8 to 9 ft over these waters outside of the Bahamas. Moderate to fresh tradewinds are occurring elsewhere across the central and western Atlantic south of 27N. Gentle to moderate winds cover the central Atlantic north of 27N. Moderate to occasionally fresh north to northeast winds are occurring over the eastern Atlantic. The overall pattern will change little through the next 24 hours. Therefore, the chances for heavy rainfall over the Florida Peninsula, Bahamas, and western Atlantic will continue. For additional information please visit http://www.hurricanes.gov/marine $$ ERA