102 AXNT20 KNHC 172113 TWDAT Tropical Weather Discussion NWS National Hurricane Center Miami FL 0005 UTC Thu Mar 18 2021 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 2100. ...MONSOON TROUGH/ITCZ... The monsoon trough extends from the coast of Africa near 12N15W to 02N25W. The ITCZ continues from 02N25W to 01N37W. Numerous moderate and scattered strong convection is observed within 360 nm of the coast of Liberia and Sierra Leone, east of 19W south of 07N. GULF OF MEXICO... A cold front is moving off the Texas coast and into the far western Gulf of Mexico now, extending from 29N96W to 26N98W. Ahead of the front, fresh to strong southerly winds prevail across the central Gulf of Mexico, per an earlier ASCAT scatterometer pass. Seas are 6-9 ft across the same waters. A pre-frontal line of scattered showers and thunderstorms has formed offshore of Texas and southwest Louisiana, mainly north of 27N, extending northward to the Texas/Louisiana border. This line of thunderstorms will move from west to east across the northwest to the north-central Gulf this evening. By midnight tonight local time, the line of thunderstorms will be near the coast of Mississippi and southeast Louisiana. Some of the thunderstorms to the north of 28N are likely to be strong to severe, with frequent lightning, gusty winds, small hail and isolated waterspouts. Fresh to strong southerly flow will prevail through tonight ahead of the cold front. The front will reach from the Florida Panhandle to the central Bay of Campeche Thu morning, and from southern Florida to the Yucatan peninsula Fri morning before moving southeast of the basin Fri night. Brief gale-force NW winds are expected near the Veracruz coast of Mexico midday Thu. Fresh to strong N to NE winds and building seas are expected in the northeast Gulf Sat night through Sun night. CARIBBEAN SEA... An earlier ASCAT scatterometer pass indicated the presence of a surface trough in the southwest Caribbean from the southeast coast of Nicaragua to the north coast of Panama near 09N80W. This surface trough and a mid-level trough over the southern portion of Central America are enhancing scattered moderate convection over the southwest Caribbean from 10N-12N between 80W-84W. Heavy rain could impact the southeast coast of Nicaragua through tonight. A cold front extends from west of the Azores through 32N35W to Montserrat to just south of Puerto Rico and ending inland over the Dominican Republic. Cloudiness with possible scattered showers are within 45 nm either side of the front, including near Antigua, Montserrat, St. Kitts and Nevis, and the Dominican Republic. The cold front is forecast to drift SE across the northeast Caribbean through Thu. A surface trough extends from St. Lucia east-northeastward to 17N53W. Scattered showers are possible near St. Lucia and Martinique. An earlier ASCAT scatterometer pass showed moderate to fresh winds covering most of the Caribbean, with strong NE to E winds over the central Caribbean. Strong E to SE winds are also likely occurring in the Gulf of Honduras. Seas are likely currently 7-11 ft in the central Caribbean, 5-8 ft in the eastern Caribbean and 4-7 ft in the NW Caribbean, except 5-8 ft in the Gulf of Honduras. Strong tradewinds will prevail across the central Caribbean through Fri morning, with near gale-force winds expected near the coast of Colombia each night. Fresh to strong winds are expected in the Windward Passage tonight. SE winds will increase across the NW Caribbean through tonight, ahead of a cold front moving into the NW Gulf of Mexico. The front will move southeast across the Yucatan Channel Fri night, then meander across the northwest Caribbean and western Cuba through Sun. Large northerly swell will affect the Tropical N Atlantic waters and Caribbean Passages through Thu. ATLANTIC OCEAN... A cold front extends from 1015 mb low pressure northwest of Bermuda near 35N70W to near Savannah, Georgia. Ahead of the front, scattered moderate showers and isolated thunderstorms are occurring from 29N-32N between 68W-76W, although this activity has been dissipating somewhat in the past few hours. Fresh S to SW winds are located in the same area. Gentle to moderate anticyclonic winds prevail elsewhere north of 22N and west of 65W, due to surface ridging. An exception is in the Straits of Florida, where fresh SE winds were seen on earlier ASCAT scatterometer data. A cold front extends southwestward across the central Atlantic from west of the Azores through 32N35W to Montserrat to just south of Puerto Rico and ending inland over the Dominican Republic. The earlier ASCAT scatterometer data showed fresh NE winds north of the front to 22N between 55W-77W. These winds are locally strong just north of the Mona Passage. A pre-frontal surface trough is analyzed from 28N40W to 18N47W. Cloudiness and scattered showers are along the cold front and the surface trough. Large NW to N swell of 8-16 ft associated with the cold front covers the Atlantic west of a line from 32N28W to 20N40W to 14N61W and east of around 70W. Seas are 5-8 ft elsewhere east of the Bahamas, in northerly swell. For the forecast, the cold front extending from the Tropical N Atlantic waters to the northeast Caribbean will drift southeast and weaken through late Thu. Large northerly swell will affect the waters east of 72W through Thu. The cold front north of Florida will move east of northern Florida Thu night, extend from near 31N71W to the Straits of Florida Fri evening, then become stationary on Sat. A new area of low pressure forming along this stationary front will intensify northerly winds east of northern Florida Sun and Sun night, with gale conditions possible. $$ Lewitsky/Hagen