000 AXNT20 KNHC 131043 TWDAT Tropical Weather Discussion NWS National Hurricane Center Miami FL 543 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 0600 UTC surface analysis and satellite imagery through 1000 UTC. ...ITCZ/MONSOON TROUGH... The Monsoon Trough extends from the African coast near 08N13W to 06N20W. The Intertropical Convergence Zone axis extends from 06N20W to 03N32W to 03N38W to the Equator near 45W. A surface trough remains embedded within the ITCZ along 38W. Widely scattered moderate convection is from the Equator to 09N between 10W-31W. Isolated moderate convection is from 02N-07N between 31W-44W. ...DISCUSSION... GULF OF MEXICO... West-southwesterly flow aloft is occurring over the Gulf basin this morning with water vapor imagery indicating mostly dry air and subsidence providing overall fair sky conditions. At the surface...a surface ridge anchored by a 1020 mb high centered across the NE Gulf waters near 28N83W continues to further support the tranquil conditions...however a stationary front remains analyzed across the coastal plain from southern Georgia to eastern Texas. 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 16N74W 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 21N between 78W-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 adjacent coastal waters 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 noted across adjacent coastal waters this morning 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 morning 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 32N81W. Pre-frontal surface troughing extends from 33N71W SW to near 29N78W and is providing focus for scattered showers and widely scattered tstms from 26N-32N between 64W-76W. 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 34N46W. Within the southeastern periphery of the ridging...a weakening frontal boundary extends as a cold front from 32N26W SW to 28N35W...then as a dissipating stationary front SW to 24N50W. Isolated showers and tstms are occurring N of 30N within 90 nm E of the front with isolated showers possible S of 30N within 90 nm either side of the front. For additional information please visit http://www.hurricanes.gov/marine $$ HUFFMAN