000 AXNT20 KNHC 201804 TWDAT Tropical Weather Discussion NWS National Hurricane Center Miami FL 1805 UTC Mon Dec 20 2021 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... Gulf of Mexico Gale Warning: A strengthening low pressure is over the W central Gulf near 23N93W. It will sustain near-gale to gale force winds and seas at 11 to 14 ft off the Mexico coast, NE of Tampico and S of Matamoros through this afternoon. As the low tracks northeastward this evening and Tue morning, it will shift near-gale winds and seas of 8 to 10 ft into the N central Gulf. Please refer to the latest High Seas Forecast issued by the National Hurricane Center, at the following website: https://www.nhc.noaa.gov/text/MIAHSFAT2.shtml, for more details. Atlantic Gale Warning: The aforementioned low pressure in the Gulf of Mexico will move northeastward across northern Florida Tue, and into the Atlantic Tue evening. This strengthening low will cause gale force southerly winds from late Tue evening into Wed morning, mainly N of 28N and W of 72W. Seas of 10 to 13 ft are also likely in the area of gale force winds. As the low moves well NE of the area and in the wake of the cold front, conditions will slowly improve by Wed night. Please refer to the latest High Seas Forecast issued by the National Hurricane Center, at the following website: https://www.nhc.noaa.gov/text/MIAHSFAT2.shtml, for more details. Eastern Atlantic Gale Warning from 35W eastward: Gale-force winds are forecast in the zone named IRVING, W of Madeira. An Azores low pressure center and two frontal boundaries are to the north of 25N from 31W eastward. These conditions are expected to continue until 21 December at 21 UTC. Please refer to the Meteo-France High Seas Forecast on the following website, http://www.gmdss.org/bulletins/METAREA2.HIGH_SEAS_WARNING.1956.19 1956225601.html, for more details. ...MONSOON TROUGH/ITCZ... An ITCZ extends westward from SW of Liberia at 04N10W to 03N32W, then continues west-northwestward from 04N36W to near the Guyana coast. Scattered moderate to isolated strong convection is flaring up near the first ITCZ from 02N to 07N between 15W and 32W. Scattered showers are seen near the second ITCZ from 02N to 07N between 35W and 43W, and from 06N to 12N between 46W and 58W. The E Pacific monsoon trough is triggering scattered showers and isolated thunderstorms near Panama and nearby Caribbean waters. ...GULF OF MEXICO... Please see Special Features section above for details on near-gale to gale conditions in the Gulf through Tue morning. A stationary front extends eastward from a 1012 mb low over the W central Gulf at 23N93W to NW of Cuba at 23N85W, then continues as a weakening cold front through the Straits of Florida. Scattered showers and thunderstorms are flaring up near the low and across the N central Gulf. Another cold front curves southwestward from this same low through the Bay of Campeche into S Mexico. Scattered showers are found over the Bay of Campeche. Outside the influence of the gale winds, fresh to strong ENE to SE winds and seas of 7 to 9 ft are present over the N and central Gulf. Similar conditions with NW winds are noted for the Bay of Campeche. Moderate to locally fresh ENE to ESE winds and seas at 4 to 7 ft prevail for the rest of the Gulf. For the forecast, the stationary/cold front that extends from the low to the Straits of Florida is beginning to stall early this morning, and should retreat northward as a warm front Tue. Meanwhile the second cold front over the Bay of Campeche will continues to move E through Tue as the low tracks NE toward N Florida. Gales offshore Veracruz early this morning will propagate NE through the day, to the N and W of the center of the low, and into the N central Gulf of Mexico. The low and cold front will move E and through the basin by later on Tue, with strong winds and high seas impacting most of the basin, before conditions improve Wed, as weak high pressure builds into the area. ...CARIBBEAN SEA... Refer to the Monsoon Trough/ITCZ section for weather in the Carribbean Basin. Gentle to moderate easterly trade winds and seas of 5 to 8 ft are evident across the central and E Caribbean Sea. Mainly gentle easterly trades with seas at 3 to 5 ft prevail for the NW Gulf. For the forecast, as the Bermuda High remains weak and centered well NE of the Caribbean, the trade winds will only reach moderate to fresh over the S central Caribbean and gentle to moderate elsewhere for the next several days. A cold front will move through the Yucatan Channel Tue, then reach from E Cuba to Nicaragua by Thu morning, before stalling. Fresh N winds can be expected behind this front. Large N to NE swell will continue in the tropical N Atlantic into Tue. ...ATLANTIC OCEAN... Please see Special Features section above for gale and high sea conditions that will develop offshore from N Florida on Tue and ongoing in the far eastern Atlantic S of the Azores. A cold front extends northeastward from the NW Bahamas to beyond NE of Bermuda. Scattered showers and thunderstorms are occurring near the front N of 27N between 65W and 79W. Strong mid to upper- level winds are spreading lots of high clouds over the E tropical Atlantic, including the Cabo Verde Islands. The southwestern end of a second weakening cold front is generating scattered showers and thunderstorms near the Canary Islands. A large dome of 1020 mb high centered near 27N47W is dominating the central Atlantic Basin with light to gentle winds and seas of 4 to 6 ft N of 22N between 40W and 65W. Farther E, Gentle to moderate with locally fresh SW to WNW winds and seas of 9 to 12 ft are found N of 25N between the NW African coast and 34W. Mostly moderate to fresh NE to ENE trades and seas of 8 to 10 ft are seen from 02N to 20N between the central African coast the Lesser Antilles. Gentle to moderate SE to SW winds and seas of 5 to 7 ft prevail for the remainder of the basin. For the forecast W of 65W, the cold front from west of Bermuda through the NW Bahamas to the Florida Straits will track east today, with little additional southward progress. Strong E winds will occur N of 29N in association with it today. Low pressure developing in the Gulf of Mexico and moving northeastward to offshore NE Florida and Georgia today into Tue will cause the W portions of the front to retreat northward as a warm front. Near the low, strong to gale force winds are expected over N waters Tue into Wed night. Building high pressure behind the low should lead toward tranquil conditions on Thu and Fri. $$ Chan