Atlantic Tropical Weather Discussion
397 AXNT20 KNHC 181640 TWDAT Tropical Weather Discussion NWS National Hurricane Center Miami FL 1815 UTC Fri Sep 18 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 1200 UTC surface analysis and satellite imagery through 1600 UTC. ...TROPICAL WAVES... A central Atlantic tropical wave has its axis along 40W, S of 21N, moving westward 10 to 15 kt. Scattered moderate isolated strong convection is from 08N to 16N between 35W and 44W. A cluster of strong convection is occurring along the N end of the wave, from 21N to 23.5N between 41W and 44W. A central Caribbean tropical wave has its axis along 77W-78W, S of 19N to eastern Panama, moving westward at around 15 kt. Isolated moderate convection is noted S and W of Jamaica, while numerous strong convection is noted along the intersection of the wave and the eastern Pacific monsoon trough, across the coastal waters of Panama and Colombia. ...MONSOON TROUGH/ITCZ... The monsoon trough enters the Atlantic along the coast of Senegal near 14N17W and continues southwestward to 09N22W to 13N34W to 13N44W. The ITCZ extends from 11N44W to 12.5N50W, then resumes from 11N53W to 10.5N61W. Aside from convection associated to the tropical waves as described above, scattered moderate isolated strong convection is noted from 06N to 12.5N between the coast of Africa and 34W. A small 1014 mb low about the ITCZ near 12N50.5W is producing scattered moderate convection within 120 nm across the N semicircle of the low. ...GULF OF AMERICA... The old frontal trough extending from the Atlantic near the NW Bahamas and across portions of S Florida and into the SE Gulf is no longer clearly identifiable. However, associated low level moisture persists across the southern Gulf S of 26N between Florida and Mexico. Scattered moderate isolated strong convection is occurring within this band of moisture from 22N to 26N between the Straits of Florida and 94.5W. At the surface, a broad high pressure ridge extends across the southeastern U.S. along about 34N, and is promoting gentle to moderate easterly winds across the basin N of 25N, where seas are 4 to 7 ft. A surface trough is along 89-90W from 23N to 26.5N and is aiding in focusing convection to its east, and promoting the strongest winds and seas across the basin across the northern end of the trough. Light to gentle mostly easterly winds prevail S of 25N, where seas are 2-4 ft. A weak thermal surface trough is over the eastern Bay of Campeche, with another weak trough extending from the nearshore waters of SE Texas to near Veracruz, Mexico. Scattered showers are within 90 nm of Veracruz and within 45 nm of the NE Mexico coast. For the forecast, the pressure gradient between high pressure over the southeastern U.S. and a dissipating frontal trough over the southern Gulf supports moderate to locally fresh E-NE to E winds and moderate seas over the northern Gulf. These conditions will gradually improve later today into Sat as the frontal trough dissipates. Meanwhile, a rather broad upper-level low will move towards Florida from the western Atlantic today, and into the NE Gulf on Sat. This feature will lead to increasing shower and thunderstorm activity over Florida, and then over the eastern and central Gulf waters. Fairly tranquil marine conditions are forecast by the end of the weekend into early next week. ...CARIBBEAN SEA... Please refer to the tropical wave section for details on a wave in the central Caribbean including associated convection. Westerly winds aloft across the northwest Caribbean are supporting scattered moderate convection across the Gulf of Honduras and near the tropical wave. Elsewhere, fair skies prevail across the basin. The pressure gradient between weakening high pressure over the western Atlantic and relatively lower pressure in northern South America is allowing for fresh to strong trades over the central Caribbean S of 17N between 66W and 77W, where seas are 6-9 ft. Moderate to fresh trades are found elsewhere from 10N to 19N to the east of 80W, along with 4-7 ft seas. Gentle to moderate winds and 2-5 ft seas prevail across the remainder of the basin, except for seas to 6 ft across southwest portions across the western coastal waters of Panama. For the forecast, the pressure gradient between high pressure over the western Atlantic and the Colombian Low will generally maintain fresh to strong trades along with moderate to locally rough seas over most of the central Caribbean through early Sat morning. Winds will diminish to moderate to fresh speeds thereafter as the pressure gradient relaxes across the area. Moderate or weaker winds and slight to moderate seas are forecast elsewhere. ...ATLANTIC OCEAN... A weakening stationary front extends from near 31N70W southwestward to near the coast of Vero Beach, Florida, where it becomes ill defined across the peninsula. across the NW Bahamas and to the Florida Keys. Broad upper level low pressure over northern Florida is promoting unstable conditions across much of the area W of 68W. Converging low level moisture associated with the front is producing scattered moderate isolated strong convection from 23N to 28.5N between the Straits of Florida and 68W. Recent satellite scatterometer data shows gentle to moderate NE winds to the N of the front, where seas are 4 to 6 ft. S of the front, winds are light to gentle between 60W and S Florida, except for fresh SE winds along the N coastal waters of Hispaniola to 22N. Weak high pressure and light winds prevail E of the front to about 46W, where a low level trough is interacting with an upper- level trough to produce scattered to locally numerous moderate convection from 24.5N to 31N between 40W and 55W. Farther NE, a 1023 mb is centered near 35N45W and extends a broad ridge south and southwestward across the eastern and central Atlantic. Moderate NE to E trades prevail S of 25N between the Cabo Verdes and the tropical wave along 40W, where seas are 5 to 7 ft. Well to the east, fresh to strong N-NE winds and 6-9 ft seas are found from 16N to 22N between Africa and 22W due to a tight pressure gradient between low pressure across NW Africa and the Atlantic ridge. Moderate to fresh N-NE winds and 6-9 ft seas elsewhere from 16N to 31N to the east of 28W. Moderate or weaker winds and moderate seas dominate the remainder of the tropical Atlantic waters. For the forecast west of 55W, a weakening stationary front that extends from near Bermuda to the central Florida coast will gradually wash out today. Conditions will improve early on Fri as high pressure becomes the dominant feature across the basin during the weekend into early next week. Meanwhile, abundant tropical moisture, combined with an upper- level low located east of Florida, will continue to support scattered to numerous showers and thunderstorms, mainly W of 70W, through at least Sun.