000 AXNT20 KNHC 211000 TWDAT Tropical Weather Discussion NWS National Hurricane Center Miami FL 600 AM EDT Sun May 21 2017 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 0600 UTC surface analysis and satellite imagery through 1000 UTC. ...TROPICAL WAVES... A tropical wave is in the central Atlantic with axis extending from 11N30W to 04N31W, moving west at 10 kt within the last 24 hours. The wave is in a region of unfavorable wind shear and most of the wave environment is under the Saharan dry air and dust, which is hindering convection. A tropical wave is in the far eastern Caribbean with axis extending from 14N62W to inland Venezuela near 07N63W, moving west at 15 kt within the last 24 hours. Similar to the wave in the central Atlantic, the wave environment is characterized by unfavorable wind shear, and the presence of abundant Saharan dry air and dust, which support the lack of convection. ...ITCZ/MONSOON TROUGH... The Monsoon Trough enters the tropical Atlantic near 08N13W and continues to 06N22W. The ITCZ extends from 06N22W and then continues to 06N29W, then resumes west of a tropical wave at 06N34W to 05N48W to the coast of Brazil near 06N57W. Scattered moderate convection and tstms are from 06N-09N east of 20W and from 04N-08N west of 48W. ...DISCUSSION... GULF OF MEXICO... Numerous heavy showers and tstms are over southern Alabama, Georgia and the Florida Panhandle extending south to 28N in the Gulf. Moisture advection from the Caribbean by SE wind flow and upper level diffluence between a ridge over the eastern CONUS and a trough over the central plains support this convection. Strong winds up to 30 kt are associated with this area of convection off the coast. Another region of upper level diffluence is between the base of the trough over Texas and westerly flow across the Gulf. This upper level environment supports scattered showers within 120 nm off the coast of Texas ahead of the next front to enter the basin later today. Moderate return flow dominates the basin, except within 135 nm off the northern Yucatan Peninsula where a surface thermal trough support fresh winds. A second and stronger cold front is forecast to come off the Texas coast Tuesday night. CARIBBEAN SEA... Numerous heavy showers and tstms are in the SW Caribbean S of 12N associated with the monsoon trough that crosses Costa Rica and Panama to a low over NW Colombia as well as upper level divergence. The pressure gradient between strong high pressure in the Atlantic and lower pressure across the western half of the basin continue to support fresh to strong winds with the strongest winds being within 150 nm off the Colombia coast and in the Gulf of Honduras. Latest scatterometer data indicate fresh NE flow across the Windward Passage. Moderate trades and shallow clouds with possible isolated showers are across the remainder basin. Otherwise, a tropical wave lacking convection is in the far eastern Caribbean. For further details see the tropical waves section. ...HISPANIOLA... Daytime heating, local sea breezes and mountain upslope lifting will combine with available shallow moisture to produce some cloudiness with scattered to isolated showers mainly during the afternoon and early evening hours today and Monday. ...ATLANTIC OCEAN... High pressure prevails across most of the Atlantic Ocean being anchored by a 1022 mb high near Bermuda and a 1023 mb high in the central basin near 29N39W. A middle to upper level trough between 55W and 70W continue to support s surface trough NE of Puerto Rico from 27N56W to 21N62W. Scattered to isolated showers and tstms are mainly east of the trough N of 20N between 50W and 60W. A cold front will enter the north central Atlc waters Monday night. Otherwise, surface high pressure will dominate elsewhere. For additional information please visit http://www.hurricanes.gov/marine $$ Ramos