000 AXNT20 KNHC 182254 TWDAT Tropical Weather Discussion NWS National Hurricane Center Miami FL 654 PM EDT Sat Mar 18 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 2215 UTC. ...ITCZ/MONSOON TROUGH... The Monsoon Trough extends from the African coast near 06N10W to the Equator near 24W. Widely scattered moderate convection is S of 06N between 12W-35W. ...DISCUSSION... GULF OF MEXICO... Water vapor imagery indicates mostly dry air and stable conditions over much of the basin as an upper level trough axis extends from over the Florida Big Bend region W-SW to 27N95W over the NW Gulf waters. The stable conditions aloft continue to support surface ridging anchored by a 1028 mb high centered near 27N87W and a 1026 mb high centered along the Mexico coast near 21N97W. Gentle to moderate anticyclonic wind flow prevails across the basin this evening as the high will gradually drift westward through early Sunday. As the high shifts...a cold front is expected to emerge off the Gulf coast E of 90W tonight and sweep southward across the Florida peninsula and far eastern waters through Sunday afternoon. Ridging west of the front will remain the primary influence for the Gulf Monday and Tuesday. CARIBBEAN SEA... Mostly west-southwesterly upper level flow is noted on water vapor imagery over much of the Caribbean basin this evening. This southwesterly flow over western portions feed NE into broad upper level troughing over the central North Atlc in support of a stationary front analyzed from the Windward Passage to eastern Honduras near 15N83W. Widely scattered showers and isolated tstms are occurring within 150 nm either side of the front. Some of the low-level moisture and isolated shower activity continues to feed across interior portions of Nicaragua...Honduras...and Guatemala. Otherwise...a few isolated showers are possible across the eastern Caribbean from 12N-17N between 62W-69W. Moderate to fresh trades are expected through the overnight hours into Sunday...generally E of the front...while moderate to fresh NE winds will prevail across the NW Caribbean through the overnight W of the front. The overall pressure gradient generating these winds is expected to relax by Sunday afternoon. ...HISPANIOLA... West-southwesterly flow aloft over the island in addition to a stationary front analyzed across the Windward Passage and adjacent western coastal waters is providing for isolated showers this evening. The front is expected to become diffuse by Sunday... however isolated afternoon showers remain possible due to the weakened remnant boundary. ATLANTIC OCEAN... A stationary front extends into the discussion area near 32N49W SW to 26N60W to the Turks and Caicos islands then to the Windward Passage and into the west-central Caribbean Sea. Scattered showers and isolated tstms are occurring within 150 nm either side of the boundary. A 1027 mb high centered near Bermuda continues to provide mostly fair conditions to the remainder of the SW North Atlc...however by late tonight into early Sunday the next cold front is expected to emerge off the SE CONUS coastline with fresh to strong SW winds ahead of the front and fresh to strong NW winds after frontal passage. This frontal system is expected to reach the central Atlc waters by Tuesday as high pressure builds back in across the SW North Atlc waters. Farther east...the remainder of the central Atlc is under the influence of a surface ridge anchored by a 1029 mb high centered across the Azores near 39N27W. Finally...a weakening and broad 1012 mb low is centered in the vicinity of the Canary Islands near 29N18W. Isolated showers are possible across the Canary Islands...however is expected to dissipate by Sunday evening as it drifts southward. For additional information please visit http://www.hurricanes.gov/marine $$ HUFFMAN