000 AXNT20 KNHC 271717 TWDAT Tropical Weather Discussion NWS National Hurricane Center Miami FL 1805 UTC Wed Nov 27 2024 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 1700 UTC. ...SPECIAL FEATURES... Significant Swell Event: Long-period NW swell producing seas of 12 to 15 ft, with period of 14 to 18 seconds, is propagating through the north-central Atlantic subtropical waters in the wake of an old frontal boundary that extends from near 31N29W to 24N40W and to 23N50W. The highest seas currently dominate the waters N of 28N between 33W and 53W. The swell set will continue to shift eastward and gradually subside through Thu. Please read the latest high seas forecast that was issued by the National Hurricane Center, at the website- https://www.nhc.noaa.gov/text/MIAHSFAT2.shtml, for details. ...MONSOON TROUGH/ITCZ... The monsoon trough axis enters the Atlantic from the coast of Sierra Leone near 08N13W and continues to 07N20W. The ITCZ extends from 07N20W to 04N30W to 05N45W to the Brazil/French Guiana border. Scattered moderate convection is noted from 03N to 07N between 10W and 40W. ...GULF OF MEXICO... A stationary front extends over the far N Gulf. Otherwise, relatively weak high pressure is present over the basin, with a 1022 mb high pressure inland Mexico roughly between Tampico and Veracruz. Recent scatterometer data indicate moderate to fresh southerly winds over the NW Gulf and gentle to moderate NE winds over the far southeastern Gulf and the Straits of Florida. Seas are generally 3 to 4 ft within these wind speeds. Elsewhere, light to gentle winds and slight seas prevail. For the forecast, the stationary front over the far N Gulf will lift N as a warm front today. A cold front is forecast to enter the NW Gulf waters Thu morning. Moderate to fresh southerly winds will develop over the western Gulf through tonight ahead of this front. The front will shift across the Gulf waters before moving SE of the basin this weekend. Fresh to strong northerly winds and building seas will follow this front. Gusty winds with occasional gusts to gale force may occur over the west-central and SW Gulf W of the front on Fri. High pressure building in the wake of the front will shift E through Sun night as a trough develops in the far western Gulf. The resulting pressure gradient will support fresh to strong easterly winds and building seas over the waters W of 90W. ...CARIBBEAN SEA... A plume of deep, tropical moisture ahead of a mid to upper-level trough that stretches from the Bahamas to Cuba and to Honduras is helping to sustain a large area of showers and thunderstorms over the central Caribbean. This convective activity extends from La Guajira Peninsula in Colombia northward to southern Hispaniola. This activity is accompanied by frequent lightning, heavy rain likely reducing visibility at time and gusty winds. A 1009 mb low pressure is analyzed near 14N74W. The eastern portion of the E Pacific monsoon trough extends from northern Costa Rica to northern Colombia. Scattered shower, with embedded thunderstorms, are near the trough axis. The pressure gradient between the low and higher pressure over the western Atlantic is generally supporting moderate to fresh NE to E winds across most of the basin. Seas are in the range of about 3 to 5 ft, except for slightly higher seas of 4 to 6 ft between the Cayman Islands and NE Honduras where mostly fresh NE winds are observed. For the forecast, moderate to fresh trades are expected over most of the basin through Sat night, except for locally strong NE winds in the lee of eastern Cuba through tonight. Winds will strengthen over the NW Caribbean toward the end of the weekend. A large area of numerous thunderstorms accompanied by frequent lightning and heavy rain will reduce visibility and produce locally gusty winds and higher seas over portions of the central Caribbean today. ...ATLANTIC OCEAN... Please refer to the Special Features section for details about the ongoing long-period swell event affecting a portion of the north-central Atlantic waters. A surface trough is analyzed from near 26N73W to the Windward Passage. ASCAT data show fresh to locally strong E winds on the E of the trough axis, particularly from 22N to 24N to about 70W where a cluster of moderate convection is also noted. To the NE of the trough, high pressure of 1020 mb is centered near 28N56W. Farther east, the aforementioned old frontal boundary extends from near 31N29W to 24N40W and to 23N50W as a trough. Fresh SW winds are N of 28W and E of the trough to about 28W. A swell event follows this frontal trough. High pressure over the eastern Atlantic, with a center of 1020 mb located near 25N27W, is allowing for moderate to locally fresh trades farther south over the tropical Atlantic, where 5 to 8 ft seas persist. Satellite derived wind data indicate the presence of another surface trough crossing the Canary Islands. Gentle to moderate winds are on either side of the trough axis. Seas to 8 ft in N swell are reaching these islands. Seas of 8 to 9 ft also in N swell dominate the waters N of 21N between 18W and 25W. Elsewhere, gentle to moderate winds and moderate seas prevail. A broad moisture plume is streaming north-northeastward from the central Caribbean Sea to across the Atlantic waters between 50W and 73W. Scattered showers along with small patches of light to moderate rain are underneath these clouds. An area of scattered showers and isolated thunderstorms is approaching the Lesser Antilles. This convective activity is the result of an upper-level low in that area. For the forecast, the above mentioned trough will move westward, reaching the central Bahamas and eastern Cuba by tonight, and the NW Bahamas and central Cuba late on Thu before weakening. A cold front is expected to move into the NW part of the area Thu night into Fri. The front is forecast to move across the waters through the weekend before becoming stationary from near 31N59W to central Cuba on Sun. Moderate to fresh winds and moderate seas will follow the front. $$ GR