888 AXNT20 KNHC 161818 TWDAT Tropical Weather Discussion NWS National Hurricane Center Miami FL 1805 UTC Sat Dec 16 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 stationary front extends westward from the western Atlantic across the central Bahamas and Florida Straits to the southeastern Gulf of Mexico near 24N86W, then continues northwestward as a warm front to a deepening 1009 mb low at the central Gulf of Mexico near 25N90W. To the north, there are two strong high pressures, a 1033 mb high over the U.S. Mid-Atlantic States and a 1029 mb Bermuda High. Tight gradient between these features will maintain near-gale to gale ENE to E winds along with 11 to 16 ft seas across the central and eastern-central Gulf of Mexico, southeast Florida offshore waters today. As the low at the central Gulf of Mexico tracks northeastward toward the Florida Big Bend area and deepens further tonight, these winds and seas will shift into the northeastern Gulf of Mexico, and the offshore waters of central/northeast Florida and northwest Bahamas. This low is expected to cross northern Florida and southern Georgia early Sunday morning and exit into the western Atlantic on by Sunday afternoon. This will cause gale to strong gale southerly winds and very rough seas of 16 to 22 ft to shift northward and eastward into the western Atlantic waters northeast of a line from 31N80W to 26N72W. On the other hand, this will allow winds and seas across the eastern Gulf of Mexico and southeast Florida offshore waters to gradually subside. Residual Large ENE Swell East of the Bahamas: Decaying ENE swell will remain large enough to sustain 12 to 14 ft seas from 22N to 27N between 68W and the Bahamas through early this evening. Afterward, the ENE swell will subside further and allow seas to drop below 12 ft late this evening. By Sunday afternoon, seas will rise again as winds increase to between near- gale and gale-force in respond to a deepening low pressure moving across norther Florida and souther Georgia. For the above Gale Warning and Swell Event, 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. Gale Warning at the Central Atlantic: A 1017 mb low pressure currently located near 29N52W will drift southeastward today. Latest satellite scatterometer data continue to show near-gale to gale-force NE winds just north and northeast of the low from 28N to 31N between 49W and 51W. Earlier satellite altimetery data also reveal seas of 12 to 15 ft in this area. As the low shifts farther southeast this afternoon, the associated pressure gradient will gradually weaken and winds are expected to fall below gale-force by late afternoon. However, a broad area of 12 to 16 ft seas reinforce by increasing large NE swell will sink southward and dominate the waters north of 25N between 49W and 58W through tonight. Please read the latest NWS High Seas Forecast issued by the National Hurricane Center at https://www.nhc.noaa.gov/text/MIAHSFAT2.shtml for more details. ...MONSOON TROUGH/ITCZ... The monsoon trough remains over the Africa continent. An ITCZ extends westward from just west of Sierra Leone at 07N14W across 04N30W to 07N47W. Scattered to numerous moderate convection is evident up to 100 nm along either side of the ITCZ east of 27W. West of 27W, widely scattered to scattered moderate convection is seen up to 40 nm north, and 100 nm south of the ITCZ. ...GULF OF MEXICO... Please read the Special Features section about a ongoing Gale Warning. Besides the stationary front mentioned in the Special Features section, a surface trough runs northward from the Yucatan Peninsula through a 1009 mb low at the central Gulf near 25N90W to the central Louisiana coast. Scattered showers and isolated thunderstorms are occurring near the tough and, east and of the low across the north-central, east-central and northeastern Gulf. Similar convection is also noted near the stationary front across Florida Straits. Another cold front curves southwestward from near the Texas-Louisiana border through Brownsville, Texas. Patchy rain are found near and up to 50 nm northwest of this boundary. Outside the Gale Warning area, fresh to strong ENE to ESE winds and seas of 8 to 11 ft dominate the north-central and eastern Gulf, including the Florida Straits. Fresh to strong northerly winds and 7 to 10 ft seas are present across the western Gulf, including the western Bay of Campeche. Moderate to fresh NNE to SE to SW winds with 7 to 11 ft seas in large NE swell prevail for the rest of the Gulf. For the forecast, a strong 1033 mb high pressure over the U.S. Mid-Atlantic States will support strong winds over the northern and eastern Gulf of Mexico into tonight, with easterly gales offshore of Florida through this afternoon. As the 1009 mb low continues to strengthen and move northeastward across the Gulf toward the Florida Big Bend area through tonight, and inland into the Florida Big Bend area later tonight. This will produce additional gales in the northeastern Gulf tonight. Thunderstorms in association with this low will provide locally higher winds and seas through tonight. The cold front currently off the Texas coast will sink farther southeastward across of the Gulf through Sun. Strong northerly winds will spread into the central and north- central Gulf this evening through Sun behind the front. Afterward, high pressure will then settle in over the area through early next week allowing for marine conditions to improve. ...CARIBBEAN SEA... A surface trough runs southeastward from the Gulf of Mexico across the Yucatan Peninsula to the Gulf of Honduras. Convergent southeasterly winds east of the trough axis are triggering scattered showers and isolated thunderstorms near western Cuba and the Cayman Islands. Otherwise, a 1029 mb Bermuda High continues to channel trade winds across much of the basin. Fresh with locally strong easterly winds and seas of 6 to 8 ft are present just south of Hispaniola. Moderate to fresh E to ESE winds and 5 to 7 ft seas exist at the lee of Cuba and north of northwest Colombia. Light to gentle winds and 4 to 6 ft seas in moderate easterly swell are evident at the Gulf of Honduras and southwestern basin. Moderate E to SE winds and seas at 4 to 6 ft prevail elsewhere in the Caribbean Sea. For the forecast, the Bermuda High will continue to support fresh to strong trade winds across the north-central basin today, before it shifts eastward and weakens, causing winds to gradually diminish into tonight. A cold front will move through the Yucatan Channel and into the northwestern basin tonight, stretch from eastern Cuba to Nicaragua Mon morning, then stall and weaken from central Hispaniola to Panama Wed. Fresh to strong NW to N winds will follow this front, becoming N to NE on Wed. ...ATLANTIC OCEAN... Please read the Special Features section about a ongoing Gale Warning and significant swell. A cold front curves southwestward from a 1017 low near 31N50W to well north of Puerto Rico at 23N66W, then continues westward as a stationary front across the central Bahamas to beyond the Great Bahama Bank. Widely scattered showers are seen up to 50 nm along either side of this boundary east of the Bahamas. Over the Bahamas and Great Bahama Bank, scattered showers and isolated thunderstorms are occurring. Convergent trade winds are producing scattered showers from 17N to 21N between 50W and Hispaniola, and also from 12N to 14N between 50W and the Windward Islands. A weakening stationary front runs southwestward from 31N36W to 22N40W. Widely scattered moderate convection is seen up to 60 nm east of this feature north of 27N. Outside the Gale Warning and Significant Swell areas, fresh to strong NE to E winds and seas of 8 to 11 ft are evident north of 19N between 50W and the Florida east coast. Near the Canary and Cabo Verde Islands, moderate to fresh NE to ENE trades and 4 to 6 ft seas in moderate northerly swell are noted north of 06N between the Africa coast and 30W. For the central Atlantic, light to gentle winds and seas at 5 to 7 ft in moderate mixed swell are found from 20N to 27N between 30W and 50W. For the tropical Atlantic, gentle to moderate ENE to E winds and 5 to 7 ft seas dominate from 05N to 20N between 30W and the Lesser Antilles. Light to gentle southerly winds and 5 to 7 ft in mixed swell prevail for the remainder of the Atlantic Basin. For the forecast, The cold/stationary front will become completely stationary along 23N this afternoon and begin to weaken. The pressure gradient between the strong high pressure building north of the area and the front will result in near gale to gale-force NE to E winds and high seas over the waters W of 65W and north of 23N through tonight. Gulf of Mexico low pressure will move northeastward across northern Florida tonight, then emerge along the southeast coast of the U.S. on Sun. A large area of southerly gales will develop southeast of the low and an associated cold front tonight through Sun night. Numerous thunderstorms in association with this low will provide locally higher winds and seas through Sun. Gale-force winds will lift north of the areal waters Mon night as the cold front reaches from near Bermuda to the Windward Passage, then will stall from just east of Bermuda to Hispaniola Tue night. $$ Chan