000 AXNT20 KNHC 231804 TWDAT Tropical Weather Discussion NWS National Hurricane Center Miami FL 104 PM EST FRI DEC 23 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 1745 UTC. ...THE ITCZ/THE MONSOON TROUGH... The Monsoon Trough extends from the coast of Liberia Africa near 05N09W to 05N14W. The ITCZ begins near 05N14W and continues along 03N30W to 04N46W to the coast of Guyana near 06N57W. Scattered moderate convection is noted within 120 nm N of the ITCZ W of 25W. ...DISCUSSION... ...THE GULF OF MEXICO... High pressure ridging anchored over Virginia continue to build in across the basin, thus providing mainly moderate NE to E flow E of 90W and moderate E to SE flow across the western half. Localized fresh NE to E wind is noted in the Florida Straits and the SE Gulf S of 26N E of 85W. Seas are 1 to 3 ft over northern Gulf waters while 2 to 4 ft seas are across the southern half of the basin. Over the SW Gulf waters, a 1019 mb low is centered near 19N94W with an associated surface trough extending from 17N93W to the low to 23N96W. Shallow moisture over this region of the basin may support isolated showers in the vicinity of this low that is forecast to dissipate within the next 24 hours. Mainly moderate return flow will dominate the basin through the middle of next week, except near the Straits of Florida where NE to E fresh to strong flow will continue through Monday night as the pressure gradient tightens across the area. Seas will build up to 8 ft in the SE Gulf as a result. ...THE CARIBBEAN SEA... Shallow moisture moving across the E Caribbean along with middle to upper level troughing is supporting scattered to isolated showers over this region of the basin. Water vapor imagery show strong dry air subsidence elsewhere, which is supporting fair weather. A relatively tight pressure gradient across the north central portion of the basin is supporting fresh to strong NE flow through the Windward Passage, in the lee of central Cuba, and in the lee of the Dominican Republic. Otherwise, moderate to locally fresh trades prevail across the remainder of the basin. Seas are measured at 4 to 7 ft across the area as well, except up to 8 ft near the Windward Passage and in the lee of the Dominican Republic. The hotspots of stronger winds will persist through the upcoming weekend, expanding in coverage to across most of the basin by the end of the weekend through early next week as high pressure builds north of the area. Seas will build to 6 to 10 ft by early next week as the stronger winds increase in areal extent. ...HISPANIOLA... Clouds have been banking along the Dominican Republic mountain range this morning. These clouds with possible isolated showers are being supported by shallow moisture and an upper level trough. Showers will continue in the Dominican Republic through the weekend as the upper level trough stalls over the Island. ...THE ATLANTIC OCEAN... A middle to upper level trough over the NW Atlc supports a cold front from 30N69W to 28N77W. A pre-frontal trough extends from 29N70W to 26N78W. Isolated showers are in the vicinity of these two features. A second surface trough extends from 25N64W to 20N66W with no convection. High pressure ridging anchored NE of the Azores extends across the remainder Atlc forecast waters, except in the far NE basin where a surface trough extends from 28N17W to 21N18W. High pressure will build in across the basin from the north during the weekend. The high will slide to the east through the weekend with fresh to strong winds becoming confined to the waters south of 25N through the day Saturday, then to across the waters south of 27N Sunday into Monday as new high pressure builds in from the Carolinas. The pressure gradient breaks down and relaxes by Tuesday as a front or remnant trough moves across the basin, allowing for winds to diminish through the middle of next week. For additional information please visit http://www.hurricanes.gov/marine $$ Ramos