000 AXNT20 KNHC 212241 TWDAT Tropical Weather Discussion NWS National Hurricane Center Miami FL 0005 UTC Wed Dec 22 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 1800 UTC surface analysis and satellite imagery through 2230 UTC. ...SPECIAL FEATURES... .ATLANTIC GALE WARNING... A complex low is developing off the east coast of Florida, consisting of 1006 mb low near 30N78W and a deep, 1001 mb low over central Florida near 28N81W. The 1001 mb low will move into the Atlantic off northeast Florida this evening. This will cause SW to W winds to increase over the waters between northeast Florida, Bermuda, and the northern Bahamas through early Wed with seas reaching 8 to 13 ft. 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. ...MONSOON TROUGH/ITCZ... The ITCZ reaches from 02N20N to 00N30W to 00N50W. Scattered moderate convection is evident from 01N to 04N between 45W and 50W. ...GULF OF MEXICO... A cold front extends southwestward from a strong 1001 mb low pressure near Kissimmee, Florida to the western tip of Cuba. A surface trough reaches from the low pressure westward across the east-central Gulf to 27N86W. Earlier scatterometer and altimeter satellite data showed strong to near- gale force over the eastern Gulf with 8 to 11 ft seas. But winds and seas are rapidly diminishing over the eastern Gulf as the low pressure lifts to the northeast. Moderate to fresh NW flow is noted elsewhere with 5 to 7 ft seas in most areas, except for 3 to 5 ft seas in the far northwest Gulf and over the coastal waters across the northern Gulf. Dry and cool air is following the front, and no significant shower or thunderstorm activity is evident across the Gulf. For the forecast, fresh to strong winds and seas of 7 to 9 ft over the eastern Gulf will gradually subside late tonight and early Wed. High pressure crossing the northern Gulf will lead to tranquil conditions Wed night through Thu, but by Fri and into the weekend, fresh S return flow will develop in the western Gulf. ...CARIBBEAN SEA... A cold front extends southwestward from the western tip of Cuba to central Belize. Scattered showers and isolated thunderstorms are active over the northwest Caribbean within 60 to 150 nm west of the front. Fresh NW winds follow the front across the Yucatan Channel, with seas near 8 ft. Light breezes and 2 to 4 ft seas are evident ahead of the front over the northwest Caribbean. Generally moderate trade winds with 4 to 6 ft seas are noted across the remainder of the Caribbean. For the forecast, the front will gradually stall from the Windward Passage to offshore Nicaragua for the latter part the week. Fresh N winds are expected behind the front, diminishing to mainly moderate on Wed. Scattered showers and isolated thunderstorms accompany the front. Elsewhere, moderate to fresh trades will prevail over the central and eastern basin through tonight. A weakening pressure gradient will lead to less wind Wed and Thu. For tropical Atlantic waters E of the Lesser Antilles, fresh to strong trades and seas of 8 to 9 ft will prevail through Wed. ...ATLANTIC OCEAN... Please see Special Features section above for information on gales that will develop off the east coast of Florida this evening through Wed morning. A cold front reaches from 30N40W to 29N50W where it becomes stationary to 29N65W, then transitions to a warm front to the 1006 mb low near 30N78W. Another frontal boundary reaches from this same low pressure center to the 1001 mb low pressure over central Florida. The subtropical ridge is displaced slightly southward by the front, reaching along roughly 25N east of 70W, and anchored by 1019 mb high pressure near 25N51W. Scattered to numerous showers and thunderstorms are noted with 60 nm northeast of the 1006 mb low. A few showers and thunderstorms are also active from central Cuba to the northern Bahamas. Fresh to strong SW winds are observed within 90 nm west of the frontal boundary off northeast Florida. Moderate to fresh winds are evident elsewhere west of 55W, except for light winds along the ridge axis. Buoy data confirms seas are 8 to 10 ft north of the Bahamas and west of 73W. Recent altimeter data shows 8 to 10 ft seas north of 28N along the frontal boundary, associated with NW swell. Elsewhere, moderate to fresh trade winds and 7 to 10 ft seas are noted over the tropical Atlantic south of 20N with northerly swell, and gentle to moderate winds and 7 to 9 ft seas in northerly swell north of 20N. For the forecast west of 65W, in addition to the gale warning, a trailing cold front will cross the region tonight through Wed night, bringing scattered showers and thunderstorms with it. Building high pressure behind the low should lead toward tranquil conditions Thu night through Fri night. Looking ahead, a strong pressure gradient is likely to develop north of 29N this weekend in between low pressure systems tracking along 40N and the subtropical high, which will be situated along 25N, leading to strong W winds and building seas north of 29N. $$ Christensen