000 AXNT20 KNHC 191805 TWDAT Tropical Weather Discussion NWS National Hurricane Center Miami FL 1805 UTC Tue Dec 19 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... Central Atlantic Gale Warning: A 1011 mb low near 23N54W is steadily moving westward, while a broad surface ridge extends southwestward from a massive 1048 mb high at the north-central Atlantic to near 25N64W. Tight pressure gradient between these features continues to sustain strong to gale-force ENE winds and very rough seas at 18 to 23 ft north of 25N between 46W and 56W, based on latest satellite scatterometer and altimeter data. These conditions are expected to persist through today. As the low tracks farther westward and weakens this evening, winds should decrease below gale force but a large area of 12 to 19 ft seas will linger through tonight. Very Rough Seas across the Western and Central Atlantic: A stationary front curves southwestward from the eastern Azores across 31N35W to near 26N55W. Widely scattered showers are present up to 80 nm along either side of this front. A large fetch area of strong to gale winds north of this boundary continues to generate large ENE to E swell across the central and western Atlantic. Other than the Gale Warning area mentioned above, this swell will prolong very rough seas of 11 to 18 ft north of 20N between 38W and 60W, and north of 26N between 60W and 70W through this evening. Starting early Wednesday morning, seas east of 55W will gradually subside and drop below 12 ft by late Wednesday evening. Seas west of 55W will stay at 11 to 15 ft through Thursday morning due to a new set of northwesterly swell and wind waves caused by the next cold front. 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 the Gale Warning and Very Rough Seas. ...MONSOON TROUGH/ITCZ... The monsoon trough remains over the African Continent. An ITCZ meanders west-northwestward from 04N18W across 01N35W to north of French Guiana at 06N51W. Widely scattered moderate convection is observed up to 80 nm along either side of the ITCZ. ...GULF OF MEXICO... A weak cold front reaches westward from near Tampa, Florida to the central Gulf, while a surface trough runs northwestward from the eastern Bay of Campeche to west-central Gulf. No significant weather is present near both features. A surface ridge stretches southeastward from a 1023 mb high near the Rio Grande to the Yucatan Peninsula. Moderate with locally fresh NE winds and seas of 4 to 6 ft are evident across the north-central and eastern Gulf, including the Florida Straits. Gentle to moderate NE to ESE winds and seas at 2 to 4 ft prevail for the rest of the Gulf. For the forecast, the 1023 mb high will sustain moderate to locally fresh NE winds for the eastern Gulf today. Stronger high pressure will shift eastward across the central U.S. and into the eastern U.S. tonight through Thu, to produce fresh to strong NE to E winds across the eastern Gulf, including the Straits of Florida through Fri. Southeasterly flow is expected to develop Sat. ...CARIBBEAN SEA... The southern portion of a stationary front extends from the Windward Passage to the southwestern basin north of eastern Panama. A surface trough reaches northward from a 1009 mb low at the northwest Colombia coast to just south of western Haiti. Scattered showers and isolated thunderstorms are seen near these features across the central and north-central basin, including waters near Jamaica. Convergent northerly winds west of the stationary front are causing scattered showers near the coastal waters of Costa Rica and western Panama. West of stationary front, fresh to strong N winds and seas of 6 to 10 ft are noted at the southwestern basin and near the Windward Passage, while moderate to fresh N winds and 4 to 6 ft seas are found at the northwestern basin. Gentle to moderate NE to E winds and seas at 4 to 6 ft prevail elsewhere in the Caribbean Sea. For the forecast, high pressure will build southeastward across the western Atlantic tonight through Fri. This will force the northern portion of the front to drift southeast across Hispaniola this afternoon through Wed before gradually dissipating Wed night. Fresh to strong N winds behind the front will become N to NE tonight through Wed then veer NE Wed night through Thu night, with strongest winds in the lee of Cuba and through the Windward Passage. At the same time, fresh trades are expected in the south- central basin, including the Gulf of Venezuela, increasing to strong each night. ...ATLANTIC OCEAN... Please read the Special Features section at the beginning about Gale Warning and Very Rough Seas. A stationary front stretches south-southwestward from west of Bermuda across 31N68W and a 1013 mb low near 25N70W to beyond the Turks and Caicos Islands. Scattered moderate convection is flaring up near and up to 280 nm east of this boundary. At the central Atlantic, a surface trough reaches southwestward from 26N52W through the 1011 mb low mentioned in the Special Features section to 17N56W. Convergent southeasterly winds feeding toward this system are interacting with a pronounced upper-level low near 21N50W to trigger scattered to numerous moderate convection from 14N to 24N between 39W and 50W. Farther southwest, anther surface trough runs southwestward from 15N48W to 12N53W, then continues westward as a shear line to near the Windward Islands. Scattered showers are noted near this features from 11N to 15N between 50W and the Windward Islands. In the tropical East Atlantic, convergent trades are taking advantage of strong divergent flow aloft to produce scattered moderate convection from 05N to 12N between 22W and 36W. Outside the areas mentioned in the Special Features section, moderate to fresh with locally strong NE to E winds and seas of 8 to 11 ft are evident north of 20N between 38W and 70W/stationary front. Moderate with locally fresh NNE to NW winds and 8 to 10 ft are noted north fo 20N between 70W/stationary front and the Florida coast. Near the Canary and Cabo Verde Islands, moderate to fresh with locally strong ENE to E winds and 6 to 10 ft seas exist north of 12N between the Africa coast and 38W. For the tropical west Atlantic, gentle to moderate NE to SE winds with seas of 6 to 9 ft are found from 03N to 20N between 38W and the Lesser Antilles, except fresh to strong SE winds and seas of 7 to 10 ft from 14N to 20N between 44W and 48W. Gentle to moderate E to SE winds and 4 to 6 ft seas in mixed swell prevail for the remainder of the Atlantic Basin. For the forecast W of 55W, strong high pressure will build into the western Atlantic behind the front tonight through early Thu to produce fresh to strong winds, gradually diminishing to moderate to fresh Thu night and Fri. This will force the front to move southeastward and reach from 31N66W to Haiti this evening, from 31N61W to central Hispaniola Wed evening, and from 22N60W to northeastern Hispaniola Thu evening. Winds and seas will slowly subside Fri night and Sat as high pressure weakens. $$ Chan