000 AXNT20 KNHC 180610 TWDAT Tropical Weather Discussion NWS National Hurricane Center Miami FL 0615 UTC Wed Dec 18 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 0500 UTC. ..MONSOON TROUGH/ITCZ... A monsoon trough enters the Atlantic along the southern coast of Sierra Leone, then runs westward to 05N18W. An ITCZ continues from 05N18W across 04N30W to 04N47W. Widely scattered moderate convection is seen near and up to 80 nm north of the ITCZ west of 24W. No significant convection is found near the monsoon trough. ...GULF OF MEXICO... Two surface troughs are causing isolated thunderstorms at the western Bay of Campeche and the central Gulf. Otherwise, a surface ridge reaches southwestward from New Orleans to near Tampico, Mexico. Moderate with locally fresh E winds and seas at 4 to 6 ft exist at the central Gulf. Gentle to moderate NE to SE winds and 3 to 5 ft seas prevail for the rest of the Gulf. For the forecast, moderate to locally fresh E winds near the surface trough and moderate NE winds for the remainder of the Gulf will persist through early Wed. Winds will diminish Wed morning, and gentle to moderate winds will prevail across the Gulf through Wed afternoon. A cold front will move into the northwestern Gulf Wed evening, and fresh to locally strong N winds will occur along and behind the front. The front will dissipate Thu morning over the central Gulf. High pressure will build over the central United States on Fri, and cause moderate N to NE winds across the Gulf. Looking ahead, gentle to moderate E winds and slight to moderate seas are anticipated for this weekend. ...CARIBBEAN SEA... The southern end of a surface trough extending southward from the central Gulf of Mexico is generating scattered showers and isolated thunderstorms at the northwestern basin, including the Gulf of Honduras. Convergent trades are causing isolated thunderstorms near Hispaniola. A surface ridge related to a 1035 mb high at the north-central Atlantic is supporting fresh to strong ENE winds and seas of 6 to 8 ft at the south-central basin. Gentle to moderate NE to E winds and 2 to 4 ft seas are noted at the northwestern basin, and waters near Costa Rica and Panama. Moderate to fresh easterly winds and seas of 4 to 6 ft prevail elsewhere in the Caribbean Sea. For the forecast, tight pressure gradient between high pressure in the central Atlantic and building low pressure over Colombia will support moderate to fresh trade winds over the central, eastern and southwestern Caribbean through Fri morning. Periods of strong winds will occur off the coast of Colombia and Venezuela tonight into Fri morning. Strong NE winds are also expected downwind of Hispaniola and through the Atlantic Passages tonight into early Thu. Seas of 4 to 7 ft will prevail across the aforementioned areas, with locally rough seas prompted by strong winds off the coast of Colombia through late this week. A long period NE swell will produce rough seas through the Atlantic Passages Wed into Fri before diminishing. Elsewhere, gentle to locally moderate NE winds and seas of 3 to 5 ft are expected in the northwestern basin through Fri. Looking ahead, building high pressure over eastern Mexico will lead to generally moderate to locally fresh E to NE winds across the basin this weekend. ...ATLANTIC OCEAN... A cold front curves southwestward from near the Azores across 31N29W to 25N56W. Scattered showers are occurring up to 50 nm along either side of the front. A surface trough over Florida is producing scattered showers and isolated strong thunderstorms across the eastern Florida offshore waters, including the northwest Bahamas. Convergent trades are triggering similar conditions near the southeast Bahamas and Turks and Caicos. Refer to the Monsoon Trough/ITCZ section for additional convection in the Atlantic Basin. Fresh with locally strong NE to ENE winds and 9 to 11 ft seas are present north of 20N between 56W and the Florida coast/Bahamas, and north of the cold front between 43W and 56W. For the central Atlantic, gentle with locally moderate SW to NW winds and seas of 5 to 7 ft in moderate NE swell exist north of 20N between 35W and the cold front. Across the Tropical Atlantic from 05N to 20N between 35W and the Lesser Antilles, gentle to moderate ENE to E winds and 6 to 7 ft seas are evident. Gentle to moderate SE winds and seas at 4 to 6 ft in mixed moderate swells prevail for the remainder of the Atlantic Basin west of 35W. For the forecast W of 55W, the strong pressure gradient between a 1035 mb high in the north-central Atlantic and troughing over central Florida will continue to support fresh E winds across areas north of the Greater Antilles through Wed, with strong winds anticipated over the southeast Bahamas. Farther east, the cold front will progress slowly southwestward through Thu, producing widespread fresh E winds both ahead and behind the front, with strong winds occurring along the front. Rough seas associated with these features will occur 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. Very rough seas in excess of 12 ft will be possible along and behind the aforementioned cold front. Elsewhere, fresh trade winds and rough seas will prevail south of 17N through Thu before winds diminish to moderate on Fri. A cold front will move off the coast of the southeastern United States late Wed into Thu and extend from near 31N74W to southeastern Florida Fri morning, and from 31N67W to eastern Cuba by Sat morning. Fresh to locally strong N to NW winds will occur behind the front. $$ Chan