000 AXNT20 KNHC 211634 TWDAT Tropical Weather Discussion NWS National Hurricane Center Miami FL 1134 AM EST Thu Dec 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 1200 UTC surface analysis and satellite imagery through 1545 UTC. ...ITCZ/MONSOON TROUGH... The monsoon trough extends from the African coast near 05N09W to 06N16W to 05N19W. The Intertropical Convergence Zone axis extends from 05N19W to 04N28W to 01N32W to 03N39W to the Equator near 50W. Scattered moderate convection is from 01N-09N between 01W- 20W... and from 02N-13N between 25W-34W. ...DISCUSSION... GULF OF MEXICO... Middle to upper level ridging is noted on water vapor imagery over much of the basin this afternoon as a stationary front lies across the coastal plains from the Florida/Georgia border westward along 31N to the Texas/Louisiana border. A pre-frontal surface trough is analyzed from near Jacksonville W-SW to 29N83W to 28N89W. Overall clear skies prevail across much of the basin as a ridge axis extends across the basin along 24N from a 1019 mb high centered near Andros Island. Otherwise...gentle to moderate anticyclonic winds are expected through Thursday. As the ridging shifts eastward...southerly return flow across the western Gulf will increase gradually into moderate to fresh flow Thursday afternoon into the overnight hours and early Friday ahead of the next cold front forecast to emerge off the Texas and Louisiana coasts Friday night late into early Saturday morning. Fresh to near-gale force northerly winds will follow the front on Saturday. CARIBBEAN SEA... Broad middle to upper level ridging prevails over the Caribbean basin this afternoon with water vapor imagery indicating very dry and stable air aloft supporting fair weather at the surface. A surface ridge anchored across the Bahamas continues to strengthen the pressure gradient across the central Caribbean resulting in fresh to strong trades. Slightly higher...strong to near gale force winds are expected along the coast of Colombia. Little change in the synoptic pattern is expected through early next week. ...HISPANIOLA... Broad middle to upper level ridging lies to the west of Hispaniola with dry and stable NW flow prevailing over the island this afternoon. While overall tranquil conditions are expected... isolated low-topped trade wind showers are possible the next 24 to 36 hours along the north and eastern shore exposures. ATLANTIC OCEAN... Water vapor imagery indicates a mid-level shortwave trough in the vicinity of 33N70W supporting a 1009 mb low centered near 33N68W with a cold front trailing W-SE from the low to the Georgia/ Florida coast near 31N81W. Scattered showers and tstms are occurring N of 29N between 58W-72W. Otherwise...the remainder of the SW North Atlc is under the influence of a surface ridge with axis along 24N/25N anchored by a 1019 mb high centered near Andros Island. Farther east...another middle to upper level low is centered near 26N41W and supports a weak surface trough analyzed from 25N47W to 30N44W. Isolated showers and tstms are occurring primarily east of the troughing from 22N-32N between 34W-44W. The remainder of the eastern Atlc is under the influence of a surface ridge anchored by a 1041 mb high centered W-NW of the Iberian peninsula near 43N17W. For additional information please visit http://www.hurricanes.gov/marine $$ HUFFMAN