000 AXNT20 KNHC 162318 TWDAT Tropical Weather Discussion NWS National Hurricane Center Miami FL 0005 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 1800 UTC surface analysis and satellite imagery through 2300 UTC. ...SPECIAL FEATURES... Gale Warning for Gulf of Mexico, Florida Offshore and Western Atlantic: A stationary front extends westward from 24N58W to 25N80W, then continues as a warm front to a deepening 1008 mb low at the central Gulf of Mexico near 26N89W. To the north, there are two strong high pressures, a 1031 mb high over the U.S. Mid- Atlantic States offshore waters and the 1029 mb Bermuda High. Tight gradient between these features will maintain near-gale to gale ENE to E winds along with 10 to 14 ft seas across the central and eastern-central Gulf of Mexico, southeast Florida offshore waters this evening. 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 southerly winds and very rough seas of 16 to 23 ft to shift northward and eastward into the western Atlantic waters N of 26N and W of 75W. 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 Event E of the Bahamas: Decaying ENE swell will remain large enough to sustain 12 to 13 ft seas from 22N to 27N between 69W and the Bahamas through this evening. Afterward, the ENE swell will subside further and allow seas to drop below 12 ft tonight. 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 southern Georgia. 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 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 of these events. ...MONSOON TROUGH/ITCZ... The monsoon trough remains over the Africa continent. The ITCZ extends westward from just west of Sierra Leone at 07N14W to 07N47W. Scattered moderate convection is evident up to 100 nm along either side of the ITCZ E of 24W. ...GULF OF MEXICO... Please read the Special Features section above for details on the Gale Warning in effect for the E Gulf waters. Besides the deepening low and stationary front mentioned above, a surface trough runs northward from the Yucatan Peninsula through the low to the central Louisiana coast. Scattered showers and thunderstorms prevail across the eastern half of the basin. To the NW, a cold front is analyzed from 30N93W to 24N98W. Outside the Gale Warning area, fresh to strong ENE to ESE winds and seas of 8 to 12 ft dominate the north-central and eastern Gulf, including the Florida Straits. Fresh to strong northerly winds and 8 to 12 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, the 1008 mb low pressure currently near 26N89W will continue to strengthen as it moves ENE this evening and into Florida near the Big Bend overnight. This will produce additional gales in the NE Gulf tonight. Thunderstorms in association with this low will provide locally higher winds and seas into Sun morning over the eastern Gulf of Mexico. NW gales will present behind the low Sun in the NE Gulf of Mexico. A cold front will trail from the low, moving SE of the Gulf morning. Strong north winds will continue behind this front in the northern and western Gulf into Sun. 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 Yucatan Channel to the Gulf of Honduras. Convergent southeasterly winds east of the trough axis are triggering scattered showers and 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 strong easterly winds and seas of 5 to 7 ft are present SW of Hispaniola. Moderate to fresh E to ESE winds and 4 to 6 ft seas exist at the lee of Cuba and N of 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 5 ft prevail elsewhere in the Caribbean Sea. For the forecast, strong high pressure N of the region across the middle Atlantic states will support fresh to to locally strong trade winds across the north-central basin tonight, before the high pressure shifts E and weakens, causing winds to gradually diminish Sun. A cold front will move through the Yucatan Channel and into the NW Caribbean Sun, stretch from eastern Cuba to Costa Rica Mon morning, then stall and weaken from central Hispaniola to Panama by 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 event. A cold front curves southwestward from a 1018 low near 29N49W to well north of Puerto Rico at 24N59W, then continues westward as a stationary front across the central Bahamas to beyond the Great Bahama Bank. Scattered showers are noted W of 73W. To the E, a surface trough extends from a 1014 mb low near 31N36W to 23N47W with scattered showers. Outside the Gale Warning and significant swell areas, fresh to strong NE to E winds and seas of 8 to 11 ft are evident N of 18N between 60W and the Florida east coast. Near the Canary and Cabo Verde Islands, moderate to fresh NE to ENE trades and 4 to 7 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 frontal boundary will weaken tonight and dissipate by Sun. Strong to gale-force winds are noted N of this boundary from 24N to 28N W of 75W, including the NW Bahamas and offshore Florida. These winds will continue until the front dissipates. A strengthening low pressure in the Gulf of Mexico will move NE and into Florida tonight, then cross the far NW waters Sun and move N of the area Sun night. Gales ahead of the low will develop offshore Florida later tonight and Sun, then spread E and NE with time, ahead of a cold front that will trail this low. Behind the front, NW gales will also develop N of 28N by Sun night. In the vicinity of the low and along the cold front tonight through Sun night, strong thunderstorms will likely produce locally much higher winds and seas. The cold front will reach 30N75W to Central Cuba by Sun evening, then extend from 31N68W to Haiti by Mon night. The front will then stall into the middle of next week. $$ ERA