000 AXNT20 KNHC 212346 TWDAT Tropical Weather Discussion NWS National Hurricane Center Miami FL 746 PM EDT Fri Apr 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 1800 UTC surface analysis and satellite imagery through 2200 UTC. ...SPECIAL FEATURES... A tight pressure gradient between a broad low pressure system centered near 33N48W and an area of high pressure to the west is supporting gale-force winds north of 29N between 44W and 52W. Seas in this area will range between 13 to 19 ft through the gale event. These conditions will continue through tonight, ending by 1200 UTC Saturday morning. Please see the latest High Seas Forecast product under the WMO header FZNT02 KNHC and under the AWIPS header MIAHSFAT2 for further details. ...ITCZ/MONSOON TROUGH... The Monsoon Trough extends across the western Africa coast from 08N13W to 04N17W. The Intertropical Convergence Zone continues from 04N17W to 00N28W to the coast of Brazil near 02S45W. Widely scattered moderate convection is south of 05N between 16W and 40W and south of 08N east of 16W. ...DISCUSSION... GULF OF MEXICO... High pressure extends across the western Atlantic to the northeastern Gulf, supporting gentle to moderate southeast winds over the northern Gulf, moderate easterly winds over the southeast Gulf, and gentle winds over the southwestern Gulf. The combination of an upper trough and a surface trough extending from 24N86W southward across the Yucatan Channel supports numerous showers and scattered thunderstorms south of 25.5N and east of 89W. Over the next 24 hours a broad area of low pressure may develop over the southeastern Gulf as moisture spreads north and east across southern Florida. CARIBBEAN SEA... A surface trough extends from the southeastern Gulf to the Yucatan Channel near 22N86W to 19N83W to 19N79W. The combination of this surface trough and an upper level trough over the area supports numerous showers and scattered thunderstorms north of a line from 21N87W to 14N74W. Fresh easterly winds are northeast of the trough axis. Light to gentle winds are across the western Caribbean south of the trough axis. High pressure north of the eastern Caribbean supports mainly moderate trade winds over the remainder of the Caribbean. Over the next 24 hours the showers and thunderstorms over the northwestern Caribbean will gradually shift north and east as a broad area of low pressure develops over the Gulf of Mexico, and the upper trough lifts northeast. Little change is expected elsewhere. ...HISPANIOLA... Increasing moisture from an upper trough to the west of the area is spreading showers and isolated thunderstorms across the island this evening. Expect the moisture to continue to spread across the island through the weekend with showers and thunderstorms likely Saturday and Sunday. ATLANTIC OCEAN... Gale force winds are south of a 989 mb surface low located near 34N48W. See the Special Features section above for further details. A surface ridge extends across the western Atlantic anchored by a 1021 mb high centered near 29N69W. Showers are beginning to spread across the waters southeast of the Bahamas to the east of an upper trough. To the east, a cold front enters the area from 31N37W to 22N47W. A surface trough is just west of the front extending from 31N42W to 24N40W. Isolated moderate convection and thunderstorms are from 25N to 31N east of the trough to 32W. High pressure of 1019 mb centered near 28N21W dominates the remainder of the eastern Atlantic. Over the next 24 hours showers and thunderstorms will increase across the Bahamas. The gale force winds will end Saturday morning. Showers and thunderstorms will continue east of the front over the central Atlantic. For additional information please visit http://www.hurricanes.gov/marine $$ Latto