000 AXNT20 KNHC 182316 TWDAT Tropical Weather Discussion NWS National Hurricane Center Miami FL 0015 UTC Thu Dec 19 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 1800 UTC surface analysis and satellite imagery through 2316 UTC. ..MONSOON TROUGH/ITCZ... A monsoon trough enters the Atlantic near 06N10W and extends westward to 05N19W. The ITCZ continues from 05N19W to 04N35W to 02N49W. Scattered moderate convection is occurring from 02N to between 31W and 44W. ...GULF OF MEXICO... A surface trough extends from 27N89W southward through the NE Yucatan Peninsula into the northwestern Caribbean, and scattered showers and thunderstorms are occurring near the trough axis. Light to gentle winds prevail across the Gulf waters. Seas are generally in the 2 to 4 ft range, except 4 to 5 ft E of the trough axis to about 85W. For the forecast, a cold front will move into the northwestern Gulf of Mexico this evening, and move slowly southeastward and dissipate across the southern Gulf Fri. A reinforcing cold front will then move southward across the Gulf Fri and also dissipate across the southern Gulf late Sun. High pressure behind both fronts will produce brief periods of moderate to fresh northerly winds and a modest increase in seas. Looking ahead, strong high pressure behind the second front will shift slowly eastward across the eastern U.S. late Sat through Mon to produce moderate to locally fresh winds across most of the basin. ...CARIBBEAN SEA... A surface trough extends from the central Gulf of Mexico into the northwestern Caribbean. Scattered moderate convection is noted surrounding the southern portion of the trough, particularly N of 19N and W of 85W. Elsewhere, shallow moisture, embedded in the trade wind flow is moving across the region producing isolated to scattered passing showers. The tight pressure gradient between high pressure in the central Atlantic and the Colombian low is leading to fresh trades over the south- central Caribbean where seas are in the 6 to 8 ft range, with the highest seas near the coast of Colombia. Fresh to strong E winds are also noted over the NE Caribbean, including the Atlantic passages. Seas there are 6 to 9 ft in NE swell. Gentle to moderate winds dominate the remainder of the basin, with seas of 3 to 5 ft. For the forecast, a tight pressure gradient between 1034 mb high pressure NE of Bermuda and low pressure over Colombia will support moderate to fresh trade winds over the eastern and central Caribbean E of 80W through Fri morning. Winds will pulse to strong speeds each night off the coast of Colombia and Venezuela. Fresh to strong NE winds are also expected just south of Hispaniola and through the Atlantic Passages. Atlantic NE swell will produce rough seas through the Atlantic Passages through Fri evening before diminishing. Elsewhere, gentle to moderate NE winds are expected across the northwestern Caribbean through Fri. Looking ahead, high pressure building over the Gulf of Mexico over the weekend will lead to generally moderate to locally fresh E to NE winds across the basin through the weekend. ...ATLANTIC OCEAN... An area of showers and thunderstorms is affecting the waters E of south Florida, from 26N to 28N and west of 075.5W. Strong SW to W winds aloft are helping to induce this convective activity. A swirl of low clouds is spinning near 30N69W associated with a weak trough. A stationary front extends from 31N27W to 29N34W then a warm front is analyzed from 29N34W to a weak low of 1020 mb located near 28N38W based on visible satellite imagery. A cold front extends from the low center to about 24N47W, where it begins to dissipate to 23N59W. Fresh to strong NE to E winds follow the front, with seas of 8 to 13 ft. A strong pressure gradient between 1034 mb high pressure situated NE of Bermuda and broad low pressure across the SW Caribbean also supports a large area of fresh to strong E winds S of 25N and E of the Bahamas to about 56W, including the Atlantic exposures. Seas are 8 to 11 ft within these winds. A ridge dominates the remainder of the Atlantic forecast waters. Moderate to locally fresh trade winds and seas of 7 to 9 ft are observed across the tropical Atlantic. Fresh to locally strong easterly winds prevail between the Canary and the Cabo Verde Islands where seas of 5 to 8 ft. For the forecast W of 55W, strong high pressure across the central Atlantic NE of Bermuda extends a ridge SW to the N Florida and Georgia coasts. The pressure gradient south of the ridge will continue to support fresh E winds across the waters between 25N and the Greater Antilles tonight, with strong winds expected through the southeastern Bahamas. Farther east, a cold front analyzed from 24N50W to 24N63W will drift southward through Thu, producing widespread fresh to strong E winds from 28N southward to 18N. Strongest winds and seas to 12 ft along the front will shift southwest to just north of the NE Caribbean. Rough seas in NE swell will prevail north of 15N through the end of the work week before seas begin to slowly subside from north to south late Thu through early Sat. Elsewhere, fresh trade winds and rough seas will prevail south of 15N through Thu before winds diminish to moderate speeds on Fri. A cold front will move off the coast of the southeastern United States late Thu and stall, then enter the NW zones off of Florida Fri, and reach from 31N73W to western Cuba by Sat morning. Fresh to strong N to NW winds will occur behind the front. $$ KRV