Rare Fujiwhara Event Near East Coast Prompts Forecasters to Watch Two Atlantic Storms
Meteorologists say two disturbances, Invest 93L and 94L, could interact as they approach the United States, potentially merging or altering each other's paths.
A rare Fujiwhara interaction could unfold in the Atlantic as two tropical disturbances strengthen and approach the United States, potentially forming one larger storm or altering each other’s tracks.
The Fujiwhara Effect occurs when two tropical cyclones come within about 900 miles of each other and begin to feel each other's presence in the ocean, sometimes orbiting a common center. Forecasters emphasize that such events are uncommon along the U.S. East Coast, with only four instances since 1995. The current setup involves two developing systems in the Atlantic that could approach the United States within days of each other, increasing the chance they will influence each other’s trajectories as they evolve.
Two disturbances, Invest 93L and Invest 94L, are in the Atlantic and both have more than an 80 percent chance of developing into named storms by next week, the National Hurricane Center said. Invest 93L has been developing in the middle of the Atlantic and forecasters assign a 90 percent probability that it will become a tropical depression by Friday. It is currently within about 1,000 miles of the Lesser Antilles, a cluster of Caribbean islands, and forecasts suggest it could strengthen enough to be named if winds reach 39 mph. If winds intensify to 74 mph or more, it could become a hurricane.
Invest 94L is forming off the coast of Florida, closer to Puerto Rico than 93L but still behind in development. Meteorologists say the two storms appear to be forming only days apart, meaning they could reach the East Coast around the same time if their paths continue on steady courses toward the mainland. If both reach tropical cyclone strength, the Fujiwhara Interaction could begin soon after, complicating forecast models and potential impacts along the coastline.
The two systems’ proximity and timing offer a rare window into how closely spaced storms can interact. If the stronger system absorbs a weaker one, the result could be a more powerful weather event than either would have produced alone. Conversely, if the storms are similar in strength, they may repel each other and diverge, making forecast trajectories more uncertain for forecasters and residents along the coast. Forecasters stress that such outcomes are not predetermined and depend on a variety of atmospheric factors that will evolve in the days ahead.
The development also comes as the Atlantic hurricane season is near its peak. Official forecasts indicate this period—typically running from early September through mid-October—often produces the most activity. Forecasters caution that even if the Fujiwhara effect does not fully materialize, the approach of two potential storms raises the risk of heavy rainfall, strong winds, and coastal flooding in parts of the Southeastern and Mid-Atlantic states. Residents along the East Coast are urged to monitor official forecasts from the National Hurricane Center and local authorities.
Past Fujiwhara events near the East Coast have been rare and unpredictable. Since 1995 there have been only a handful of noteworthy interactions in the Atlantic, underscoring the difficulty of forecasting multiple interacting systems. As 93L and 94L continue to develop, forecasters will rely on model consensus and updated observations to refine tracks and potential impacts. The evolving situation warrants close attention over the coming days, with the potential for changes in intensity and direction as the systems near the United States.
Officials emphasize that the best course of action for communities is to stay informed and prepared. While the exact outcomes remain uncertain, residents along the East Coast should review any local emergency plans, ensure they have essential supplies, and heed advisories as forecasts are updated. The National Hurricane Center will continue to issue advisories and model updates as conditions change, with additional guidance expected as the two disturbances near tropical cyclone status and possibly move closer to U.S. shores.