462 AXNT20 KNHC 171814 TWDAT Tropical Weather Discussion NWS National Hurricane Center Miami FL 1805 UTC Sun Dec 17 2023 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 1200 UTC surface analysis and satellite imagery through 1630 UTC. ..SPECIAL FEATURES... Gale Warning for Gulf of Mexico, Florida Offshore and Western Atlantic: A cold front extends south-southwestward from a 996 mb low over Jacksonville, Florida across eastern Florida to beyond western Cuba. A warm front runs southeastward from this low across the western Atlantic to north of the southeast Bahamas near 25N72W. Tight gradient between these features and a strong 1031 mb high east of Bermuda is causing near-gale to strong gale southerly winds north of 25N between 72W and the Florida east coast, including the northwest Bahamas. Based on model guidance and buoy observations, seas in this area range from 14 to 23 ft. In addition, near-gale to gale NW winds with seas at 10 to 14 ft are occurring behind the low and cold front at the northeastern Gulf, south of the Florida Big Bend area. As the low tracks further northeastward into western Atlantic waters offshore from Georgia/South Carolina this afternoon and evening, gale to strong gale winds and very rough seas will gradually shift northward from the southeast Florida and northwest Bahamas offshore waters. For the same reason, winds will decrease below gale force, and seas should subside below 12 ft at the northeastern Gulf of Mexico later this afternoon. Central Atlantic Gale Warning: A Strong 1031 mb high pressure is shifting slowly eastward across the north Atlantic from east of Bemuda. In response, increasing gradient between this high and a stationary front near 29N46W will generate near-gale to gale-force NE winds and rough seas of 12 to 14 ft north of 27N between 40W and 55W by this afternoon. These conditions are expected to last through Monday night with seas peaking between 16 and 21 ft. Please read the latest NWS High Seas and Offshore Waters Forecasts issued by the National Hurricane Center at https://www.nhc.noaa.gov/text/MIAHSFAT2.shtml and https://www.nhc.noaa.gov/marine/offshores.php for more details on both Gale Warnings. ...MONSOON TROUGH/ITCZ... A monsoon trough enters the Atlantic near the Sierra Leone-Liberia border, then run westward to near 08N17W. An ITCZ continues westward from 08N17W across 05N30W to 04N43W. Scattered moderate convection is seen up to 100 nm north, and 200 nm south of these features. ...GULF OF MEXICO... Please read the Special Features section above about an ongoing Gale Warning. A secondary cold front extends southwestward from near the Mississippi-Florida border to the western Yucatan Peninsula. Some patchy showers are found behind the front at the north-central Gulf south of New Orleans. Outside the Gale Warning area, fresh to strong NW to NNW winds and seas of 8 to 10 ft dominate the eastern Gulf, except mainly fresh W winds and 6 to 8 ft seas at the Straits of Florida. Gentle NNW winds and seas at 4 to 6 ft are present offshore the Texas coastline. Moderate to fresh NNW winds and seas of 7 to 9 ft prevail for the rest of the Gulf, including the Bay of Campeche. For the forecast, the cold front associated with the 996 mb low over Jacksonville, Florida has moved just southeast of the Gulf. Northerly gales will continue west of the low across the northeastern Gulf through mid morning. Strong NW to N winds will continue behind this front in the central and eastern Gulf through this evening. High pressure will follow the front allowing marine conditions to gradually improve. By midweek, strong high pressure north of the area will bring fresh to strong NE winds across the eastern Gulf, including the Straits of Florida. ...CARIBBEAN SEA... The southwestern end of a cold front curves southwestward from western Cuba to east of northern Belize. Patchy showers are found behind the front over western Cuba and the Yucatan Channel. A pre-frontal trough related to this front brought 4 to 7 inches of rain across Cuba in the past 24 hours, with the Island of Youth received the highest amounts. This afternoon, convergent southerly winds ahead of this front are triggering scattered showers and isolated thunderstorms over eastern Cuba, and near Jamaica and the Cayman Islands. Fresh to strong W to NW winds and seas of 6 to 8 ft are present near the front across the northwestern basin. Light to gentle winds and 3 to 5 ft seas in moderate easterly swell are noted at the southwestern basin. Fresh to strong E winds and seas of 6 to 8 ft are found at the northeastern basin, near Puerto Rico and the northern Leeward Islands. Moderate with locally fresh ENE to SE winds and seas at 4 to 6 ft prevail elsewhere in the Caribbean Seas. For the forecast, seas across the northwestern basin near the cold front will build further to near 10 ft later this afternoon. The front will reach from eastern Cuba to Costa Rica Mon morning, then stall and weaken from central Hispaniola to Panama by early Wed. Strong high pressure over the Atlantic will continue to produce fresh to locally strong winds over the northeastern basin today. ...ATLANTIC OCEAN... Please read the Special Features section at the beginning about ongoing Gale Warnings. A stationary front curves southwestward from a 1017 mb low near 31N37W across another 1018 mb low at 27.5M78.5W to 20N60w, then turns northwestward to north of the southeast Bahamas at 25N72W. It then continues as a warm front to near the Florida-Georgia border. Scattered showers and thunderstorms are occurring near the warm and stationary north of 23N between 70W and the Bahamas. A surface trough extends southwestward from the 1017 mb low across 25N46W to 17N53W. Widely scattered moderate convection is found up to 80 nm along either side of this trough. Convergent trade winds are triggering scattered showers from 12N to 15N between 50W and the Windward Islands. A surface trough is causing similar conditions east of French Guiana and Amapa State, Brazil from 01N to 06N between 44W and 50W. Outside the Gale Warning areas, fresh to strong NE to SSE winds and seas of 8 to 14 ft are evident north of 20N between 50W and the Florida east coast. Fresh to strong NE winds and 8 to 10 ft seas exist north of 25N between 40W and 50W. Near the Canary Islands, fresh to strong ENE to E winds and seas at 7 to 10 ft are found north of 19N between the northwest Africa coast and 30W. Gentle to moderate E to SE winds and 5 to 7 ft seas in mixed swell are present between 30W and 40W north of 20N/19N. Across the tropical Atlantic, gentle to moderate with locally fresh NE to ENE winds and seas of 6 to 8 ft are seen from 05N to 20N between the Cabo Verde Islands and Lesser Antilles. Light to gentle winds and 4 to 6 ft seas in mixed moderate swells prevail for the remainder of the Atlantic Basin. For the forecast, the stationary front will weaken and become ill defined later this afternoon. Fresh to strong E to SE winds are noted north of this boundary. The 996 mb low pressure will move across the far NW Atlantic waters this afternoon and will be north of 31N tonight, dragging a cold front with it. SE gales will expand offshore Florida today, ahead of the low, then spread east and northeast with time, ahead of the cold front. Behind the front, NW gales will also develop north of 27N later this afternoon. Scattered to numerous strong thunderstorms are expected ahead of the low and the cold front through tonight. The cold front will reach 31N79W to Central Cuba by this evening, then extend from 31N68W to central Hispaniola by Mon evening. The front will then move slowly eastward through midweek as high pressure builds behind it. $$ Chan