664 AXNT20 KNHC 170548 TWDAT Tropical Weather Discussion NWS National Hurricane Center Miami FL 0605 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 0000 UTC surface analysis and satellite imagery through 0540 UTC. ..SPECIAL FEATURES... Gale Warning for Gulf of Mexico, Florida Offshore and Western Atlantic: A stationary front extends westward from 23N61W to 25N77W, then continues as a warm front to a deepening 1004 mb low at the central Gulf of Mexico near 26N85W. To the north, there are two strong high pressures, a 1030 mb near 35N66W and the 1030 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 tonight. As the low at the central Gulf of Mexico tracks northeastward toward the Florida Big Bend area and deepens further, 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 73W. 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 26N between 70.5W and the Bahamas through tonight. Afterward, the ENE swell will subside further and allow seas to drop below 12 ft Sun morning. 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: Tight pressure gradient in the area continues to support gale-force winds. Latest satellite scatterometer data show near-gale to gale-force NE winds north of 29N between 46.5W and 50W. Seas of 12 to 13 ft are in this area. As the pressure gradient gradually weakens, winds are expected to fall below gale-force by Sun afternoon. However, a broad area of 12 to 19 ft seas reinforce by increasing large NE swell will sink southward and dominate the waters north of 25N between 49W and 58W. 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 exits the Africa continent near 09N13.5W to 06N17W. The ITCZ extends westward from 06N17W to 04N46W. Scattered moderate convection from 01N to 17N between the west coast of Africa and 27W. Another area of similar convection is noted from 02N to 07N between 34W and 47W. ...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 Channel through the low to the central Louisiana coast. Clusters of moderate to strong convection prevail across the eastern half of the basin. To the NW, a cold front is analyzed from 29N92W to 19N96W. Outside the Gale Warning area, fresh to strong SE to S winds and seas of 8 to 10 ft dominate the southeastern Gulf, including the Florida Straits. Fresh to strong NW to N winds and 8 to 14 ft seas are present across the western Gulf, including the western Bay of Campeche. For the forecast, a 1004 mb low pressure currently near 27N85.5W will continue to strengthen as it moves NE tonight and into Florida near the Big Bend overnight. This will produce additional gales in the NE Gulf tonight, to the N and then to the NW of the low. Thunderstorms in association with this low will provide locally higher winds and seas into Sun morning over the eastern Gulf of Mexico. A cold front will trail from the low, moving SE of the Gulf and into the NW Caribbean Sun 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 gradually 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 1030 mb Bermuda. Gentle to moderate easterly winds and 4 to 6 ft seas prevail in the central and eastern Caribbean. Light to gentle S to W winds and 4 to 6 ft seas in moderate easterly swell are evident at the Gulf of Honduras and southwestern basin. For the forecast, strong high pressure N of the region across the western Atlantic along 34N will support fresh 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 tonight, 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 stationary front extends westward from a 1016 mb low near 31N36W, then curves southwestward as a cold front before transition to a stationary front at 23N61W to 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 the low near 31N36W to 22N44W with scattered showers. Similar convection is noted north of 28N between 41W and 44W. Outside the Gale Warning and significant swell areas, fresh to strong NE to E winds and seas of 8 to 12 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 17N to 27.5N between 35W and 50W. For the tropical Atlantic, gentle to moderate NE 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, a stationary front extends from 23N55W to 22N59W then W-NW through the NW Bahamas and across S Florida. This front will weaken tonight and dissipate on Sun. Strong to gale-force E-SE winds are noted N of this boundary from 25N to 30N W of 76W early tonight, including the NW Bahamas and offshore Florida. Deepening low pressure in the E Gulf of Mexico will move NE and into Florida tonight, then move across the far NW Atlantic waters Sun and move N of the area Sun night. SE gales will develop offshore Florida later tonight and Sun, ahead of the low, 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. Ahead of the low and the cold front tonight through Sun night, strong thunderstorms will likely produce locally 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. $$ KRV