Might a storm far out at sea push waves the size of a ten-story building onto the coast? Forecasters say Hurricane Erin just might. Strengthening now in the Atlantic, Erin is expected to be the first major hurricane of the 2025 season and it’s arriving with an interesting and potentially threatening ocean phenomenon called dynamic fetch.
Dynamic fetch occurs when wind waves get caught up in the storm’s forward speed, enabling them to accumulate additional energy across long distances. Jean-Raymond Bidlot, a senior scientist in ocean modeling for the European Centre for Medium-Range Weather Forecasts, defined the impact as creating waves larger than wind strength alone would predict, especially to the right of the low-pressure center of the storm. In Erin’s case, the latest forecast suggests significant wave heights could exceed 50 feet, with the largest individual waves topping 100 feet. These won’t be single, towering walls of water like in a disaster movie they’ll be long, rolling swells stretching hundreds of meters, carrying immense power.
It should be pointed out, however, that dynamic fetch waves are distinct from rogue waves. Rogue waves are brief, one-time giants that can burst forth at any moment, usually in otherwise moderate seas. Dynamic fetch waves, on the other hand, are created in a sustained, predictable manner by the motion and structure of the storm. That predictability is valuable when it comes to safety planning, particularly for shipping and coastal resources management.
Even if Erin remains far out at sea, its wave energy will travel outward. Bidlot was clear that waves tend to radiate away from the storms, propagating towards coastal areas even though the brunt of the storm might still be miles away from the coast. This translates into risky surf, lethal rip currents, and beach erosion that may reach the shore days before any rain or wind associated with the hurricane itself. AccuWeather senior hurricane expert Alex DaSilva cautioned that these conditions have the potential to create major shipping disruptions as well as alter itineraries for cruise ships. For the maritime sectors, diverting around these huge swells has the potential to create delays, higher fuel expenses, and logistical nightmares.
The threat is not confined to open water. Along the Eastern Seaboard, already a lethal threat more than 50 individuals have died from them in U.S. waters this year rip currents come into their own during Erin’s heights. Regions such as North Carolina’s Outer Banks, Long Island’s South Shore, and parts of Canada’s Atlantic seaboard might experience particularly potent currents. For swimmers, a compliance with local warnings is a given. As DaSilva pointed out, even a Category 3 hurricane would generate waves close to the center in the 50–75 foot range with smaller but still hazardous surf reaching the coast.
Historically, record hurricane-generating waves have caused significant impacts on shipping operations. Previous storms have caused container vessels to take detours of thousands of miles, pushed back vital cargo delivery schedules, and even destroyed offshore equipment. The twist is that forecasting technology and ocean modeling have come so far that ships and ports have more lead time to get ready. Models now all agree, says the National Hurricane Center, that Erin will turn north of Florida before making landfall in the Bahamas, sparing Florida but not from the swell.
The worry for coastal communities, however, goes beyond day-to-day safety. Huge swells can quicken erosion, particularly where existing shoreline is already being lost to rising oceans. The Atlantic shore is eroding by an average of 2–3 feet per year, and storms such as Erin can remove barrier dunes and beaches in a matter of hours. Although most beaches recover naturally in a few years, human construction in areas of erosion can hinder that process and make it more expensive. As erosion rates along the Gulf Coast testify up to 6 feet annually in certain locations storm-induced losses can have long-term economic and environmental implications.
Nevertheless, Erin’s wave heights are based on science with a silver lining: forecasters can now accurately anticipate these threats. By learning about dynamic fetch and monitoring wave energy transport, coastal officials can give advance warning, ports can modify schedules, and beachgoers and boaters can make informed decisions. It’s a reminder for weather enthusiasts of the raw power of the ocean and of the importance of combining innovative modeling with lucid, timely information.
