000 AXNT20 KNHC 130503 TWDAT Tropical Weather Discussion NWS National Hurricane Center Miami FL 1202 AM EST TUE DEC 13 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 0000 UTC surface analysis and satellite imagery through 0430 UTC. ...ITCZ/MONSOON TROUGH... The Monsoon Trough extends from the African coast near 06N11W to 03N22W. The Intertropical Convergence Zone axis extends from 03N22W to 02N37W to 01N50W. A surface trough remains embedded within the ITCZ along 37W. Widely scattered moderate convection is from 01N-08N between 10W-42W ...DISCUSSION... GULF OF MEXICO... West-southwesterly flow aloft is occurring over the Gulf basin this evening with water vapor imagery indicating mostly dry air and subsidence providing overall fair sky conditions. At the surface...a surface ridge anchored by a 1019 mb high centered across the NE Gulf waters near 29N85W continues to further support the tranquil conditions...however a stationary front remains analyzed from southern Mississippi to eastern Texas near 30N94W then along the Texas coast to near Corpus Christi. Mostly gentle to occasional moderate southerly winds are expected through Tuesday night when the stationary front will begin moving as a cold front across the northern half of the basin and eventually into the SW North Atlc region by Thursday night. Brief fresh to strong N-NE winds are expected across the NW Gulf waters Thursday morning in association with the frontal passage. CARIBBEAN SEA... A broad upper level anticyclonic circulation is anchored over the eastern Caribbean near 16N69W with water vapor imagery indicating mostly dry air E of 77W and increased cloudiness and moisture W of 77W. As tropical moisture advects northwestward then northward within the western periphery of the upper level ridging over the western Caribbean...widely scattered showers and isolated tstms are occurring mostly S of 20N between 80W-90W...including portions of Central America and the NW Caribbean waters. Farther east... mostly clear skies prevail with only a few quick-moving low- topped isolated showers occurring in the vicinity of the Lesser Antilles...Puerto Rico...and portions of Hispaniola. Trades are expected to remain in the fresh to strong range through early Wednesday and then decrease slightly as the regional pressure gradient relaxes across the basin. ...HISPANIOLA... Passing isolated showers are across the island this evening associated with very shallow moisture. Fresh to strong trade winds are also occurring across the island and the adjacent coastal waters due to strong high pressure anchored in the central Atlc. These conditions are expected through Wednesday when surface high pressure will shift eastward and the pressure gradient relaxes across the region. ATLANTIC OCEAN... West-southwesterly flow aloft prevails over much of the SW North Atlc region this evening with overall troughing extending from over Nova Scotia Canada S-SW to over the northern Florida peninsula. This troughing supports a cold front analyzed across the western North Atlc waters to the South Carolina coast near 33N79W. Pre-frontal surface troughing extends from 32N74W SW to near 29N79W and is providing focus for scattered showers and widely scattered tstms from 27N-34N between 64W-77W. The cold front will move eastward and skirt N of 30N through Tuesday night moving into the central North Atlc waters thereafter. Across the central Atlc...a surface ridge influences much of the area anchored by a 1031 mb high centered near 34N51W. Within the eastern and southern periphery of the ridging...a weakening frontal boundary extends as a cold front from 32N31W SW to 26N47W...then as a dissipating stationary front westward to 25N63W. Isolated showers are possible within 90 nm either side of the front. For additional information please visit http://www.hurricanes.gov/marine $$ HUFFMAN