Tropical Weather Discussion

Full Alert Message

Tropical Weather Discussion NWS National Hurricane Center Miami FL 0615 UTC Sat Mar 21 2026 Tropical Weather Discussion for North America, Central America Gulf of America, 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... East Atlantic Long-period N Swell: Very large, long-period north swell generated by a large fetch of gale-force winds in the northeast Atlantic will continue to propagate southward of 31N through Sun. Expect seas of 12-20 ft tonight, subsiding to 12 to 16 ft on Sat, mainly N of 19N and east of about 38W. Seas over these northeastern waters will gradually diminish in areal coverage with the remaining very rough seas subsiding below 12 ft near the Canary Islands Mon. Please refer to the latest High Seas Forecast issued by the National Hurricane Center at website https://www.nhc.noaa.gov/text/MIAHSFAT2.shtml for more details. ...MONSOON TROUGH/ITCZ... The monsoon trough axis enters the Atlantic through the coast of Sierra Leone near 07N12W and continues southwestward to 04N18W, where it transitions to the ITCZ that continues to 00N30W to just inland Brazil near 01S44W. Scattered moderate convection is from 00N to 06N between 10W and 30W. Numerous moderate to strong convection is elsewhere from 02S to 05N between 34W and 51W. ...GULF OF AMERICA... A basin-wide ridge is centered by a 1021 mb high located over the NE Gulf near 28N86W. The pressure gradient between this ridge and a cold front over the central Caribbean is leading to fresh N to NE winds across the SE Gulf, along with seas of 4 to 7 ft. Moderate or weaker winds and slight to moderate seas are elsewhere. For the forecast, the pressure gradient between the ridge across the Gulf region and a cold front over the central Caribbean Sea will continue to support fresh NE winds and moderate seas over the SE Gulf, including the Straits of Florida, through tonight. Moderate to fresh NE winds are expected nightly, through the forecast period, across the eastern Bay of Campeche due to local effects associated with a trough. Elsewhere, moderate or weaker winds, and slight to moderate seas will prevail through Tue. Winds may briefly increase to fresh speeds over the NE Gulf late Tue into early Wed as the pressure gradient tightens there. ...CARIBBEAN SEA... A cold front extends from Windward Passage to the offshore waters of Colombia. Mainly moderate to fresh NNE winds follow the front, with locally strong winds being observed in the lee side of southern Cuba and offshore Nicaragua. Seas are moderate to 6 ft behind the front. Ahead of the front, over the eastern Caribbean, winds are moderate or weaker from the SE and seas are slight to moderate. For the forecast, fresh to locally strong N winds and moderate to rough seas will continue behind the front, which is forecast to dissipate tonight. Afterward, moderate to locally strong NE winds will remain in the western Caribbean, including the lee side of Cuba and the Windward Passage through early Sun as high pressure develops across the northern Bahamas in the wake of the front. As the ridge shifts slightly eastward, fresh to strong winds and moderate to rough seas will develop offshore Colombia Sun night and prevail through Wed night. ...ATLANTIC OCEAN... Refer to the Special Features section for details on large northerly swell that is impacting the far northeast waters of the discussion area. A cold front extends from SE of Bermuda near 31N64W to a 1010 mb low pressure located near 28N67W to eastern Cuba into the central Caribbean Sea. A pre-frontal trough is parallel to the boundary from 23N66W across Hispaniola to 17N74W. Scattered heavy showers are in the vicinity of the front between 56W and 75W. The pressure gradient between the front and high pressure building toward the region from the SE U.S. is leading to fresh to strong N winds and rough seas west of the front to about 77W. Ahead of the front to 56W, winds are fresh to strong from the SSW and seas are rough to 11 ft. In the east Atlantic, a dissipating stationary front lies between the Canary Islands and the Cape Verde Island. The pressure gradient between the low pressure system associated with this front and a strong and broad ridge across the central subtropical Atlantic waters continues to support strong to near gale-force W to NW winds over the waters between the NW coast of Africa to about 30W where seas are veru rough in the range of 13 to 20 ft. For the forecast W of 55W, fresh to strong winds and rough seas on either side of the front, and mainly N of 25N, will continue to affect the offshore waters from west to east through Sun as the front moves eastward as a cold front. This system is forecast to reach from 31N63W to Hispaniola by Sat morning, and from 31N57W to Puerto Rico by Sun morning. Looking ahead, a new cold front is forecast to enter the offshore waters of NE Florida Mon night into Tue, followed by fresh to strong NE to E winds and rough seas. These marine conditions are forecast to affect most of the waters N of 27N through the middle of the next week.