Atlantic Tropical Weather Discussion
650 AXNT20 KNHC 180006 TWDAT Tropical Weather Discussion NWS National Hurricane Center Miami FL 0015 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 1800 UTC surface analysis and satellite imagery through 2345 UTC. ...TROPICAL WAVES... A central Atlantic tropical wave has its axis along 35W from 03N to 18N, moving westward near 15 kt. Numerous moderate convection is within 240 nm west of the wave from 11N to 16N, and from 08N to 13N between 32W and the wave. A central Caribbean tropical wave has its axis along 72W. It is moving westward at 10 to 15 kt. Only isolated showers and thunderstorms are near the wave north of 16N. ...MONSOON TROUGH/ITCZ... The monsoon trough axis enters the Atlantic near 17N16W and continues southwestward to 12N30W to 10N40W and to 09N50W, where it transitions to the ITCZ to 11N59W. Aside from convection associated to the tropical waves as described above, scattered moderate to isolated strong convection is evident from 06N to 11N between 18W-21W, and from 10N to 14N east of 20W to inland Africa. Scattered moderate convection is within 120 nm north of the trough between 47W-50W. ...GULF OF AMERICA... A trough axis is analyzed from just west of the Bahamas, southwestward across extreme South Florida and to just north of the Florida Keys, reaching to near 24N86W. A western Gulf trough extends from 28N96W to 24N97W and to near 19N93W. An upper-level low is seen in water vapor imagery to be shifting westward over the northern Yucatan Peninsula. Satellite imagery shows scattered moderate convection over the Gulf waters from 23N to 26N between 84W and 92W. Isolated showers and thunderstorms are elsewhere south of about 28N and west of 83W. Similar activity is over some sections of the Straits of Florida. Another trough extends from the western Atlantic to south Florida to 24N86W. The pressure gradient between a 1025 mb high center centered over eastern Tennessee and the aforementioned trough that is over the southeastern Gulf continues to sustain fresh northeast to east winds over the NE and north-central Gulf waters. Moderate seas are occurring with these winds. Elsewhere, moderate or weaker winds, and slight seas, are noted. For the forecast, the aforementioned pressure gradient will spread westward over the remainder of the northern Gulf waters through tonight before improving Fri into Sat. Meanwhile, a rather broad upper-level low will move toward Florida from the western Atlantic on Fri. This feature will lead to increasing shower and thunderstorm activity over Florida, then across the eastern and central Gulf waters. ...CARIBBEAN SEA... 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 south- central Caribbean. Seas in the range of 6 to 8 ft are over these waters. Moderate to fresh trades along with moderate seas are elsewhere E of 82W while gentle to moderate trades and seas of 2 to 4 ft are W of 82W, except for higher seas of 4 to 5 ft south of 17N as noted in a satellite scatterometer data pass. Upper-level divergence east of an upper-level low that is over the northern Yucatan Peninsula is supporting scattered showers and isolated thunderstorms over the northwestern Caribbean. An upper-level disturbance riding along a jet stream branch is keeping active weather in the form of numerous moderate convection over the waters from 11N to 17N west of 80W to inland (near 85W) of Honduras and Nicaragua. Scattered moderate convection is over the interior of Honduras. For the forecast, the aforementioned pressure gradient will generally maintain fresh to strong trades along with moderate to locally rough seas over most of the central Caribbean through Fri night. The trades will diminish to moderate to fresh speeds over the upcoming weekend as the pressure gradient relaxes across the area. Moderate or weaker winds and slight to moderate seas are forecast elsewhere. ...ATLANTIC OCEAN... A stationary front extends from near 31N68W southwestward to 27N75W and to extreme South Florida. Moderate to fresh northeast winds and seas 5 to 6 ft are north of of the front. Scattered moderate convection is seen north of about 23N and west of 66W in association to this frontal boundary. Light to gentle winds and slight seas are southeast of the front north of 23N and west of 55W. An upper-level trough that extends from north of Puerto Rico and the U.S. Virgin Islands to around 31N is supporting scattered moderate to isolated strong convection between 59W and 62W, and also north of 26N between 40W and 59W. Fresh to locally strong north to northeast winds and moderate seas per latest satellite scatterometer data passes are near the Canary Islands. They extend westward to near 30W. Elsewhere, gentle to moderate winds and moderate seas prevail. For the forecast west of 55W, the pressure gradient between high pressure over the southeastern U.S. and a stationary front that extends from near Bermuda to the NW Bahamas will maintain moderate to fresh NE winds and moderate seas west of the front through this evening. Conditions will improve early on Fri as high pressure becomes the dominant feature across the basin into the weekend. 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 west of 70W through at least Sun.