Potential tropical systems that could form in the coing days near the U.S. East Coast.
NOAA
The global tropics are quite active right now. Typhoon Ragasa has killed at least 21 people in Asia, and now the Atlantic basin is quite active. Hurricane Gabrielle reached major hurricane status and is headed towards Europe. Forecasters are watching the possibility that two new systems may develop. Here’s why the U.S. East Coast and Caribbean Islands should watch this scenario closely.
A man stands near debris on a waterfront road amid heavy rain due to weather patterns from Super Typhoon Ragasa in Aparri town, Cagayan province on September 22, 2025. Hundreds of families sheltered in schools and evacuation centres on September 22 as heavy rains and gale-force winds from Super Typhoon Ragasa lashed the northern Philippines and southern Taiwan. (Photo by John Dimain / AFP) (Photo by JOHN DIMAIN/AFP via Getty Images)
AFP via Getty Images
As of Wednesday morning, the National Hurricane Center is providing information on Hurricane Gabrielle, a system in the tropical Atlantic region, and one in the eastern Caribbean Sea. According to NHC, conditions are extremely favorable for both systems to form within seven days. The system in the central and western tropical Atlantic could become a tropical depression today or Thursday.
The system in the eastern Caribbean has an 80% chance of forming within the next week, and it is the one that the people along the U.S. East Coast and in the Caribbean Islands need to watch. NHC wrote, “This wave is expected to move west-northwestward at 15 to 20 mph, spreading heavy rainfall and gusty winds into Puerto Rico and the Virgin Islands today, and across the Dominican Republic beginning tonight.” Once the system turns northwestward, it could become a tropical depression near the Bahamas. Hurricane Hunter aircraft will be investigating the system later today.
Tropical Weather Outlook on September 24, 2025.
NOAA and NWS
Right now, forecast models have differing outcomes, and that is not unusual at this stage. The traditional European model brings the second system perilously close to the South Carolina coast by Monday. The current American GFS model is less aggressive with a U.S. approach and development. The European AI model is somewhere in the middle of both solutions, so the sage advice for now is to watch the models evolve in the coming days and be alert to social media hyperbole.
Though not certain at this time, the storms could be close enough to interact in very interesting way. We call it the Fujiwhara Effect. According to the National Weather Service website, “When two hurricanes spinning in the same direction pass close enough to each other, they begin an intense dance around their common center.” The NWS went on to say, “If one hurricane is a lot stronger than the other, the smaller one will orbit it and eventually come crashing into its vortex to be absorbed. In some cases, the storms can merge and become one larger storm.” According to the Hong Kong Observatory, “Fujiwhara effect’ is named after Dr. Fujiwhara of Japan who performed a series of experiments and observations on water vortices from 1921 to 1923.”
It remains to be seen if this will happen, but if it does, it could affect the track of both systems. That’s one more reason the U.S. East Coast needs to pay attention to how this plays out through the weekend.
Photograph of Typhoons Ione and Kristen displaying the Fujiwhara effect. Dated 1974. (Photo by: Universal History Archive/Universal Images Group via Getty Images)
Universal Images Group via Getty Images
Source: https://www.forbes.com/sites/marshallshepherd/2025/09/24/2-potential-tropical-threats-and-why-the-us-should-be-on-alert/
