000 AXNT20 KNHC 210406 TWDAT Tropical Weather Discussion NWS National Hurricane Center Miami FL 0615 UTC Sat Dec 21 2024 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 31N. The following information is based on satellite imagery, weather observations, radar and meteorological analysis. Based on 0000 UTC surface analysis and satellite imagery through 0355 UTC. ..MONSOON TROUGH/ITCZ... The monsoon trough enters the Atlantic through the coast of southern Liberia near 05N08W and continues westward to 04N18W. The ITCZ stretches from 04N18W to 04N35W and to NE Brazil near 03N51W. Scattered moderate convection is observed from 03N to 07N and between 32W and 39W. ...GULF OF MEXICO... A weak cold front extends across the Florida Straits to just off northern Yucatan and generally dry conditions are found across the northern and eastern Gulf waters and the Bay of Campeche. However, a few showers are seen in the western Gulf, also affecting Tamaulipas. A strong ridge over the northern US extends into the Gulf of Mexico, forcing fresh to locally strong northerly winds in the northern Gulf waters, especially north of 27N. Seas in these waters are 4-6 ft. Elsewhere, moderate to locally fresh northerly winds and moderate seas are prevalent. For the forecast, a cold front will enter the northern Gulf of Mexico tonight and drift southward this weekend before dissipating over the eastern basin on Sun. Fresh to locally strong N to NE winds will occur along and behind the front tonight into early Sat north of 28N. Otherwise, moderate to locally fresh N to NE winds will prevail over the remainder of the Gulf tonight through Sat in the wake of another cold front in the far southeastern basin. High pressure will build over the central United States this weekend and drift slowly eastward, and ridging will extend into the Gulf of Mexico, resulting into moderate NE to E winds this weekend into next week. ...CARIBBEAN SEA... A dissipating front extends from central Cuba to NE Yucatan, but no significant convection is noted with this boundary. Farther east, a surface trough and divergence aloft support scattered showers and isolated thunderstorms in the north-central Caribbean, affecting portions of Hispaniola, Puerto Rico and the US Virgin Islands. Localized heavy rainfall may occur, resulting in flash flooding. Scattered showers are also noted in the SW Caribbean waters, impacting SE Nicaragua, Costa Rica and Panama. Elsewhere, generally dry conditions are present. The pressure gradient has relaxed some in the Caribbean Sea, allowing for moderate to locally fresh NE-E winds and moderate seas. However, due to the presence of the surface trough, weaker winds are noted in the north-central Caribbean waters. For the forecast, moderate to locally fresh NE winds will occur across the western half of the Caribbean through Sun as a series of weakening cold fronts drift southward and dissipate this weekend. Elsewhere, moderate to locally fresh trades will prevail over the central and eastern Caribbean. Slight to moderate seas will dominate the basin this weekend. Looking ahead, high pressure will build over the eastern United States and western Atlantic early next week in the wake of multiple cold fronts moving off the east coast. A strengthening pressure gradient between these features will lead to fresh to locally strong NE to E winds across much of the Caribbean Mon through Wed, particularly through the Windward Passage. ...ATLANTIC OCEAN... A cold front extends from a low pressure system off New England to the NW Bahamas and the Florida Straits. Another frontal boundary is analyzed ahead, extending from near 31N71W to the central Bahamas and central Cuba. A recent scatterometer satellite pass also depict a surface trough extending from 30N70W to a 1013 mb low pressure just north of the Turks and Caicos Islands and continuing to Haiti. Divergence aloft is sustaining scattered showers and isolated thunderstorms east of the surface tough to 60W. Fresh to strong W-NW winds and seas of 6-9 ft are occurring behind the frontal boundaries and north of the Bahamas. Meanwhile, fresh to locally strong SE-S winds are noted between 55W and 68W. Seas in the area described are also 6-9 ft and confirmed by an altimeter pass from a few hours ago. Elsewhere in the SW North Atlantic (west of 55W), moderate or weaker winds and moderate seas are prevalent. Farther east, a 1009 mb low pressure system centered near 32N43W extends a stationary front southward from a triple point axis near 31N38W to 18N49W. Scattered moderate to isolated strong convection is found ahead of the frontal boundary to 30W and north of 23W. The pressure gradient between a 1042 mb ridge just north of the Azores and the aforementioned low, front and lower pressures in the deep tropics result in fresh to near gale-force NE-E winds east of the front and north of 18N. Seas in these waters are moderate to rough, peaking near 10 ft off Morocco and 31N37W. Mariners are advised that gale-force winds are likely occurring in association with the strongest convection based on satellite-derived wind data. Moderate or weaker winds and moderate seas are prevalent elsewhere. For the forecast W of 55W, a series of cold fronts moving off the southeastern coast of the United States will progress slowly eastward this weekend into early next week. Fresh to strong NW winds will occur behind these fronts north of 27.5N through Sat morning, with the strongest winds occurring north of 29.5N and west of 72W. Rough seas associated with these fronts will spread south and east, with seas in excess of 8 ft occurring north of 27N. Farther east, ridging will drift eastward, and fresh S to SE winds will occur through Sat morning along the periphery of the ridge, generally north of 20N and east of 65W. South of 20N, moderate to at times fresh trades will prevail into the middle of next week. Looking ahead, widespread fresh to locally strong NE winds and rough seas will redevelop north of 20N Sun night through early next week as strong high pressure builds across the western Atlantic and into the local region, behind a weakening cold front. $$ Delgado