000 AXNT20 KNHC 181733 TWDAT Tropical Weather Discussion NWS National Hurricane Center Miami FL 132 PM EDT Wed Apr 18 2018 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 1700 UTC. ...MONSOON TROUGH/ITCZ... The monsoon trough extends from the coast of Africa near 08N13W to 03N13W to 02N24W. The ITCZ continues from 02N24W to 03N35W to 0N49W. Scattered to numerous moderate showers and thunderstorms are ocurring along and within 150 nm south of the monsoon trough east of 25W. Scattered showers and isolated thunderstorms are occuring along and within 120 nm north of the ITCZ west of 35W. ...DISCUSSION... GULF OF MEXICO... SE return flow winds of 15-20 kt are occuring over the northwestern Gulf and up to the Texas coast. Seas are 5 to 7 ft in this area, with 2 to 4 ft seas elsewhere across the Gulf. No shower or thunderstorm activity is noted, and none is expected through Thursday due to very stable conditions. Visibility is expected to remain unrestricted across the basin through Thursday. A narrow high pressure ridge over the northern Gulf will gradually weaken and shift eastward ahead of a cold front currently moving southward through the southern Plains and southeastern United States, resulting in the currently southeasterly flow becoming northerly by Thursday morning over the northwestern Gulf, and becoming northeast to easterly flow on Friday. The front will enter the northern Gulf tonight or early Thursday and stall over southern Florida to south Texas on Friday, before lifting back northward as a warm front on Saturday ahead of yet another late-season cold front that will be moving out of the southwestern U.S. and into Texas. The second front is expected to move across the northwestern Gulf by late Saturday, and reach from near the western Florida panhandle to the SW Gulf Sunday night. A warm front will extend eastward along the northeast Gulf coast out ahead of the cold front. CARIBBEAN SEA... A few isolated light showers were occurring over the Gulf of Honduras, and also to the south of the Mona Passage. Otherwise, generally fair weather conditions and little or no shower activity were noted eslewhere across the remainder of the Caribbean Sea. Swells to near 8 ft continue east of Windward Islands, while brisk easterly trade wind flow continues along and 150 nm north of the coast of Venezuela and Colombia. A weak surface trough located over Puerto Rico is expected to move into the Mona Passage this afternoon, and become diffuse across eastern Hispaniola by Thursday. Fresh to strong winds currently over the southern Caribbean will continue through late week, and expand north and westward into the southwestern Caribbean late Wed through late Fri as high pressure builds to the north across the Atlantc. These winds are expected to weaken Saturday afternoon, before pulsing back up to fresh to strong Sat night into Sunday. ATLANTIC OCEAN... A frontal boundary near 31N63W extended southwestward to the southern Bahamas and Turks/Caicos Islands. The southern portion of the frotnal system has stall and weakened. Scattered showers and isolated thunderstorms were occurring along and within 60 nm southeast of the front to the east of 71W. Seas of 8 to 10 ft continue north of 26N and west of front to 75W in NW swell. Seas in open waters are 4 to 6 ft elsewhere, except 2 to 4 ft off northeast Florida. The southern portion of the front should dissipate this afternoon, and gradually weaken northward through tonight, becoming diffuse on Friday. The next cold front will move into the western Atlantic from Florida late Thursday, reaching from Bermuda to south Florida by late Fri, then stall from near 25N65W to the Straits of Florida by late Sat. East winds will gradually increase to 20 kt over much of the waters west of 65W. Farther east, a 1030-mb high was located over the central Atlantic near 33N44W. The tail-end of a dissiapting cold front was located over the far east Atlantic from 21N21W to 29N29W. A large area of NW swell with wave heights of 8-15 ft will accompany this front covering a large portion of the area north of 20N and east of 45W through Friday. Seas will gradually subside to below 8 ft Saturday into Sunday. For additional information please visit http://www.hurricanes.gov/marine $$ ERA/Stewart