


Tropical Weather Discussion
Issued by NWS
Issued by NWS
551 AXNT20 KNHC 202120 TWDAT Tropical Weather Discussion NWS National Hurricane Center Miami FL 0015 UTC Thu Aug 21 2025 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 2100 UTC. ...SPECIAL FEATURES... Hurricane Erin is centered near 31.2N 73.6W at 20/2100 UTC or 450 nm W of Bermuda, moving N at 12 kt. Estimated minimum central pressure is 943 mb. Maximum sustained wind speed is 95 kt with gusts to 115 kt. Peak seas are near 48 ft near the center. Seas 8 ft or greater are covering much of the discussion waters N of 23N and W of 65W. Numerous moderate to strong convection is noted from 29N to 32N between 71W and 74W. Numerous moderate and scattered strong convection is elsewhere from 25N to 37N between 66W and 77W. Erin will move northward between Bermuda and the U.S. east coast over the next day or so. After that, the system should accelerate northeastward and east- northeastward. Swells generated by Erin will affect the Bahamas, Bermuda, the east coast of the United States, and Atlantic Canada during the next several days, producing life-threatening surf and rip currents along the beaches during the next several days. Beachgoers in those areas should follow advice from lifeguards, local authorities, and beach warning flags. Please read the latest HIGH SEAS FORECAST issued by the National Hurricane Center at website - https://www.nhc.noaa.gov/text/MIAHSFAT2.shtml and the latest Erin NHC Forecast/Advisory and Public Advisory at www.hurricanes.gov for more details. Eastern Tropical Atlantic (AL99): Satellite-derived surface wind data from earlier today revealed that a concentrated area of showers and thunderstorms located several hundred miles southwest of the Cabo Verde Islands lacks a closed surface circulation. Environmental conditions appear marginally favorable for additional development over the next day or so while the system moves west-southwestward at around 15 mph and a short-lived tropical depression could form. By the end of the week, environmental conditions are expected to become unfavorable for further development. ...TROPICAL WAVES... A tropical wave has its axis near 30W from 05N to 19N, moving westward at about 15 kt. Numerous moderate to strong convection is seen from 07N to 14N between 27W and 35W. Environmental conditions appear marginally favorable for additional development over the next day or so while the system moves west-southwestward at around 15 mph and a short-lived tropical depression could form. By the end of the week, environmental conditions are expected to become unfavorable for further development. This system (AL99) has a medium chance of becoming a tropical cyclone during the next 48 hours. An central Atlantic tropical wave has its axis near 46W from 05N to 21N, moving westward around 15 kt. The wave is producing a broad area of disorganized showers and thunderstorms. Environmental conditions appear conducive for gradual development of this system, and a tropical depression could form by this weekend while it moves near or to the north of the northern Leeward Islands. This system has a low chance of becoming a tropical cyclone in the next 48 hours and a medium chance of becoming a tropical cyclone in the next 7 days. A Caribbean tropical wave Caribbean Sea has its axis near 70W S of 20N, moving westward at 10 to 15 kt. No significant convection is present with the wave. ...MONSOON TROUGH/ITCZ... The monsoon trough enters the Atlantic near 20N17W, and extends to 11N29W and to 15N41W. Aside from convection noted in the tropical waves section above, scattered moderate convection is noted from 14N to 19N between 36W and 41W. ...GULF OF AMERICA... A weak pressure gradient is resulting in light to gentle winds and 1 to 2 ft seas across the entire basin. For the forecast, moderate to locally fresh NE to SE winds will be possible over the south-central Gulf each afternoon and evening through this weekend as a trough develops over the Yucatan Peninsula and moves westward. Otherwise, gentle to locally moderate winds and slight seas will prevail over the remainder of the basin as weak high pressure dominates the region. ...CARIBBEAN SEA... A more typical tradewind pattern is returning to the Caribbean as Hurricane Erin moves further northward and a ridge builds N of the area. Moderate to fresh winds are over the south central Caribbean with moderate winds elsewhere E of 75W. Light to gentle winds are over the waters W of 75W. Seas are in the 5-6 ft range over the south central Caribbean and 3-5 ft elsewhere E of 75W. Seas of 1-2 ft prevail W of 75W. For the forecast, fresh to locally strong trade winds and locally rough seas are expected over the central and eastern Caribbean tonight through Fri as a strengthening pressure gradient develops between low pressure over Colombia and building high pressure in the wake of Hurricane Erin in the western Atlantic. Elsewhere, fresh to occasionally strong E to SE winds will pulse in the Gulf of Honduras Thu through this weekend. A tropical wave located several hundred miles east of the Leeward Islands will encounter environmental conditions conducive for gradual tropical development, and a tropical depression could form by this weekend while it moves near or to the north of the northern Leeward Islands. There is a low chance of development within the next 48 hours, and a medium chance within the next 7 days. ...ATLANTIC OCEAN... Please see the Special Features section for information on Hurricane Erin. Seas greater than 8 ft, and winds 20 kt or greater associated with Erin are covering the waters N of 23N and W of 65W. Elsewhere, a frontal boundary enters the area near 31N41W and extends to 29N50W. Scattered moderate convection is in the vicinity of the boundary. Moderate winds, and seas of 6 ft, are in the vicinity of the frontal boundary. Elsewhere, high pressure ridging dominates the waters E of 60W. Gentle to moderate winds, and seas of 5-8 ft, generally prevail elsewhere. For the forecast, Erin is centered just N of the area, and will continue to shift further away from the forecast waters. Swells generated by Erin will affect the Bahamas, Bermuda, and the east coast of the United States during the next several days. A tropical wave located several hundred miles east of the Leeward Islands will encounter environmental conditions conducive for gradual tropical development, and a tropical depression could form by this weekend while it moves near or to the north of the northern Leeward Islands. There is a low chance of development within the next 48 hours, and a medium chance within the next 7 days. Elsewhere, a tropical wave located several hundred miles southwest of the Cabo Verde Islands will encounter environmental conditions marginally favorable for additional tropical development over the next day or so while the system moves west- southwestward at around 15 mph and a short- lived tropical depression could form. By the end of the week, environmental conditions are expected to become unfavorable for further development. There is a medium chance of development within the next 48 hours and the next 7 days. $$ AL