--------------------------------------------------------------------------- TROPICAL WEATHER DISCUSSION (NORTH ATLANTIC AREA) MESSAGES T1T2: AX A1A2: NT Date: 2026-09-15 --------------------------------------------------------------------------- Message File: T_AXNT20KNHC150402_C_KWBC_20260915040258_31523192-3596-TWDAT.txt ****0000006793**** AXNT20 KNHC 150402 TWDAT Tropical Weather Discussion NWS National Hurricane Center Miami FL 0015 UTC Tue Sep 15 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 0330 UTC. ...TROPICAL WAVES... A tropical wave axis is along 54W, S of 20N, moving west at 10 to 15 kt. Scattered moderate isolated strong convection is depicted from 12N to 17.5N between 50W and 56W. ...MONSOON TROUGH/ITCZ... The monsoon trough enters the Atlantic along the coast of Guinea near 10.5N14.5W and continues to 11N21W to 07.5N43W. The ITCZ extends from 09N44W to 11N54W. Numerous strong convection is from 06N to 14N E of 18W to the coast of Africa. Scattered moderate convection is noted from 06.5N to 13N between 18W and 28W, and from 06.5N to 12.5N between 28W and 50W. ...GULF OF AMERICA... Widely scattered showers prevail across the basin from 23N to 28N, supported by a weakening middle to upper-level trough from the Yucatan Channel to SE Texas. Evening convection across much of interior Florida continues to shift southwestward and weaken as it reaches the western coastal waters of Florida. At the surface, a 1017 mb high pressure center is just offshore SE Louisiana, and dominates the Gulf waters with anticyclonic flow. Recent scatterometer data shows light to gentle winds across the basin E of 92W, while fresh to locally strong NE winds prevail wihtin 120 nm of the coast of the Yucatan Peninsula and over the eastern Bay of Campeche, and moderate SE winds are W of 95W. Seas are generally 3 ft or less, except 3-5 ft near the Yucatan Peninsula, and 3 to locally 4 ft W of 95W. For the forecast, a weak ridge centered over the noreth-central Gulf will persist into Tue supporting relatively tranquil marine conditions across much of the basin. The exception will be the Bay of Campeche, where a diurnal trough will move westward offshore the Yucatan Peninsula each evening through late this week, bringing nightly pulses of fresh to locally strong NE winds. Starting late Tue, stronger high pressure building southward from the eastern United States, behind a weakening frontal boundary, will lead to increasing NE to E winds over the basin, with increasing winds reaching fresh to locally strong speeds, and seas building to rough over the northern Gulf Wed through Thu night. Conditions will improve Fri through Sat. ...CARIBBEAN SEA... A persistent middle to upper-level low pressure system prevails across the Greater Antilles tonight, and is supporting scattered moderate convection between Haiti and 80W, and scattered light to moderate convection across the eastern Caribbean. At the surface, weak high pressure is centered just northeast of the NW Bahamas, and extends a ridge to 60W. The pressure gradient between this ridge and lower pressures in Colombia combine to sustain fresh to strong with locally near gale-force easterly trade winds across much of the central Caribbean between 68W and 78W, as well as the Windward Passage. Seas are 6 to 9 ft across this area. Elsewhere, moderate to fresh trades prevail elsewhere, except light winds across far NW portions. Scattered to locally numerous heavy showers and thunderstorms are ongoing over the SW Caribbean between Colombia and NE Nicaragua, along the eastern extension of the E Pacific monsoon through. For the forecast, the pressure gradient between the subtropical ridge located north of the Greater Antilles and lower pressures in Colombia will support fresh to locally near gale-force easterly trade winds and moderate to rough seas across much of the central Caribbean, with moderate to fresh trades elsewhere through the workweek. Expect moderate or lighter winds and slight to moderate seas across NW portions, except for moderate to fresh winds mainly in the evenings near the Windward Passage and Lee of Cuba through midweek. Winds may diminish across the basin by the end of the week into the upcoming weekend as the pressures gradient relaxes. ...ATLANTIC OCEAN... A broad ridge dominates much of the Atlantic basin N of 10N and E of 60W, producing moderate to fresh easterly winds between 30W and 60W, except for fresh winds and scattered moderate convection near the tropical wave along 54W. A deep layered upper cyclone is interacting with a surface trough from 31N53W to 24N50W, producing scattered moderate isolated strong convection from 27N to 31N between 44W and 53W. Fresh SE winds and seas of 5 to 6 ft are occurring across NE portions of this trough. Environmental conditions near this system are forecast to become more conducive for development by the middle of this week. A tropical depression could form late this week as the system moves slowly west- northwestward over the subtropical Atlantic. There is a medium chance of tropical cyclone development within the next seven days. To the W of 60W, a 1018 mb high center is analyzed near 28N74W, and extends a weak ridge to 60W. The pressure gradient to the S of this ridge is promoting moderate to fresh trades S of 23N and through the Bahamas, with strongest winds off Hispaniola and in the Windward Passage. Elsewhere W of 30W, moderate or weaker winds and moderate seas prevail over the central and eastern subtropical waters. Broad low pressure along the NW coast of Africa in recent days has weakened and drifted westward over the Atlantic waters between NW Africa and 35W, where gentle to moderate NE to E winds generally prevail N of 10N, with seas of 4 to 6 ft. For the forecast west of 55W, a broad and weak subtropical ridge dominates much of the basin, forcing fresh E winds off Hispaniola and in the Windward Passage. On Tue, strong high pressure building southward through the eastern United States will bring a cold front into the NW waters, increasing NE winds to fresh to locally strong behind the front, and producing building seas to rough N of the Bahamas and W of 70W through early Thu. Conditions will improve later Thu into Fri. During the middle to later portion of the week, a trough of low pressure is forecast to move west- northwestward into the NE portion of the waters, bringing thunderstorms while also weakening the high and pressure gradient. $$ Stripling ########################### END OF MESSAGE SET ############################ --------------------------------------------------------------------------- Message File: T_AXNT20KNHC150950_C_KWBC_20260915095043_4522426-3615-TWDAT.txt ****0000005508**** AXNT20 KNHC 150950 TWDAT Tropical Weather Discussion NWS National Hurricane Center Miami FL 1215 UTC Tue Sep 15 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 0600 UTC surface analysis and satellite imagery through 0925 UTC. ...TROPICAL WAVES... A sharp tropical wave is along 55W, south of 21N, moving westward at 10-15 kt. Scattered moderate isolated strong convection is observed from 10N to 21N and between 47W and 57W. ...MONSOON TROUGH/ITCZ... The monsoon trough enters the Atlantic along the coast of Guinea near 11N15W and continues to 08N36W. The ITCZ extends from 08N37W to 11N54W. Scattered moderate to isolated strong convection is noted from 04N to 17N and east of 25W. ...GULF OF AMERICA... A few showers and isolated thunderstorms are occurring in the eastern Gulf waters and off Veracruz. A weak high pressure over the NE Gulf supports moderate to fresh SE-E winds and moderate seas in the Bay of Campeche and in the western Gulf, west of 95W. Elsewhere, light to gentle winds and slight seas prevail. For the forecast, a strong high pressure over the eastern United States will build southward behind a weakening cold front that will spread across the eastern Gulf waters. The tighter pressure gradient will support fresh to locally strong NE-E winds and rough seas starting in the NE Gulf tonight and spreading over the northern Gulf waters through Thu night. Elsewhere, a diurnal trough will move westward offshore the Yucatan Peninsula each evening through Thu night, bringing nightly pulses of fresh to locally strong NE winds. Conditions will improve across the basin Fri, allowing for moderate or weaker winds and slight to moderate seas during the weekend. ...CARIBBEAN SEA... The interaction between an large upper-level low pressure system over the north-central Caribbean and tropical moisture support numerous showers and thunderstorms over the SW Caribbean. This environment is also generating a few showers in the eastern Caribbean, bringing some rain to Puerto Rico and the Virgin Islands. High pressure north of the area sustains fresh to near gale-force easterly trade winds and moderate to rough seas across much of the central Caribbean. Moderate to fresh NE-E winds and moderate seas are occurring in the eastern Caribbean, Windward Passage and lee of Cuba. Elsewhere, moderate or weaker winds and moderate seas prevail. For the forecast, tight pressure gradient between the subtropical ridge located north of the islands and lower pressures in Colombia will support fresh to locally near gale-force easterly trade winds and moderate to rough seas across much of the central Caribbean, with moderate to fresh trades elsewhere from 11N to 18N. These conditions will persist through the workweek. Elsewhere, moderate or lighter winds and slight to moderate seas are expected, except moderate to fresh mainly in the evenings near the Windward Passage and Lee of Cuba through midweek. Winds may diminish across the basin by the end of the week into the upcoming weekend as the pressures gradient relaxes, with seas also slightly subsiding. ...ATLANTIC OCEAN... A pre-frontal trough is noted ahead of an approaching cold front to the NW waters producing scattered showers and isolated thunderstorms north of 28N and between 67W and 75W. Meanwhile, a large upper-level low over and east of the SE Bahamas is supporting scattered showers south of 25N and between 61W and 75W. High pressure dominates the rest of the SW North Atlantic, sustaining moderate or weaker winds and slight to moderate. Another upper-level low over the central Atlantic interacts with a surface trough analyzed along 51W and north of 24N, producing numerous showers and isolated thunderstorms north of 26N and between 45W and 61W. Environmental conditions are forecast to become more conducive for development in a few days, and a tropical depression could form late this week as the system moves slowly west-northwestward over the subtropical Atlantic. The system has a medium chance of formation over the next 7 days. A strong subtropical ridge centered north of the Azores extends southward into the central and eastern Atlantic, supporting moderate to fresh easterly winds and moderate seas between 30W and 60W. Moderate or weaker winds and moderate seas are prevalent elsewhere. For the forecast west of 55W, a cold front is approaching the waters off NE Florida and then will become stationary from Bermuda to the NW Bahamas into Wed. A tight pressure gradient between the building ridge over the eastern United States and the front will result in fresh to locally strong NE winds and seas to build to rough N of the Bahamas and W of 70W through early Thu. Conditions will improve later Thu into Fri. During the middle to later portion of the week, a trough of low pressure is forecast to move west- northwestward into the NE portion of the waters, bringing thunderstorms while also weakening the high and pressure gradient. $$ Delgado ########################### END OF MESSAGE SET ############################ --------------------------------------------------------------------------- Message File: T_AXNT20KNHC151543_C_KWBC_20260915154346_4522426-3638-TWDAT.txt ****0000005582**** AXNT20 KNHC 151543 TWDAT Tropical Weather Discussion NWS National Hurricane Center Miami FL 1815 UTC Tue Sep 15 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 1543 UTC. ...TROPICAL WAVES... A well defined tropical wave is along 56W, south of 21N, moving westward at 10-15 kt. Moderate to fresh E winds along with seas 4 to 6 ft are found in the vicinity of the wave. Scattered moderate to isolated strong convection is observed from 11N to 21N and between 51W and 59W. ...MONSOON TROUGH/ITCZ... The monsoon trough enters the Atlantic near 13N17W and continues to 07N45W. The ITCZ extends from 07N45W to 10N54W. Scattered moderate to isolated strong convection is noted from 05N to 20N and east of 26W. ...GULF OF AMERICA... A few showers and isolated thunderstorms are occurring in the eastern Gulf waters and off Veracruz. A weak high pressure over the N Gulf supports moderate E to SE winds and 3 to 5 ft seas in the Bay of Campeche. Elsewhere, light to gentle winds and slight seas prevail. For the forecast, a strong high pressure over the eastern United States will build southward behind a weakening cold front that will spread across the eastern Gulf waters. The tighter pressure gradient will support fresh to locally strong NE-E winds and rough seas starting in the NE Gulf tonight and spreading over the northern Gulf waters through Thu night. Elsewhere, a diurnal trough will move westward offshore the Yucatan Peninsula each evening through Thu night, bringing nightly pulses of fresh to locally strong NE winds. Conditions will improve across the basin Fri, allowing for moderate or weaker winds and slight to moderate seas during the weekend. ...CARIBBEAN SEA... The interaction between an large upper-level low pressure system over the north-central Caribbean and tropical moisture support scattered showers and isolated thunderstorms south of Puerto Rico. This environment is also generating a few showers in the eastern Caribbean, bringing some rain to Puerto Rico and the Virgin Islands. High pressure north of the area sustains fresh to strong easterly trade winds and moderate to rough seas across much of the central Caribbean. Moderate to locally fresh NE-E winds and moderate seas are occurring in the eastern Caribbean, Windward Passage and lee of Cuba. Elsewhere, moderate or weaker winds and moderate seas prevail. For the forecast, tight pressure gradient between the subtropical ridge located north of the islands and lower pressures in Colombia will support fresh to locally near gale-force easterly trade winds and moderate to rough seas across much of the central Caribbean, with moderate to fresh trades elsewhere from 11N to 18N. These conditions will persist through the workweek. Elsewhere, moderate or lighter winds and slight to moderate seas are expected, except moderate to fresh mainly in the evenings near the Windward Passage and Lee of Cuba through midweek. Winds may diminish across the basin by the end of the week into the upcoming weekend as the pressures gradient relaxes, with seas also slightly subsiding. ...ATLANTIC OCEAN... A pre-frontal trough is noted ahead of an approaching cold front over the NW waters producing scattered showers and isolated thunderstorms north of 27.5N and between 68W and 76W. Meanwhile, a large upper-level low over and east of the SE Bahamas is supporting scattered showers south of 26N and between 61W and 72W. High pressure dominates the rest of the SW North Atlantic, sustaining moderate or weaker winds and slight to moderate. Another upper-level low over the central Atlantic interacts with a surface trough analyzed along 51.5W and north of 26N, producing numerous showers and isolated thunderstorms north of 26N and between 46W and 54W. Environmental conditions are forecast to become more conducive for development in a few days, and a tropical depression could form late this week as the system moves slowly west-northwestward over the subtropical Atlantic. The system has a medium chance of formation over the next 7 days. A strong subtropical ridge centered north of the Azores extends southward into the central and eastern Atlantic, supporting moderate to fresh easterly winds and moderate seas between 25W and 53.5W. Moderate or weaker winds and moderate seas are prevalent elsewhere. For the forecast west of 55W, a cold front is approaching the waters off NE Florida and then will become stationary from Bermuda to the NW Bahamas into Wed. A tight pressure gradient between the building ridge over the eastern United States and the front will result in fresh to locally strong NE winds and seas to build to rough N of the Bahamas and W of 70W through early Thu. Conditions will improve later Thu into Fri. During the middle to later portion of the week, a trough of low pressure is forecast to move west- northwestward into the NE portion of the waters, bringing thunderstorms while also weakening the high and pressure gradient. $$ KRV ########################### END OF MESSAGE SET ############################