Rip currents are strong, localized and narrow currents that extend from a beach out beyond the surf zone. They are often mistakenly called an undertow, but that term is erroneous — rip currents do not exert a downward force, but rather one away from shore.
Swimmers caught in rip currents are often carried away from the beach at speeds too swift to fight against. Some beaches suspend swimming when rip currents are particularly active, but they can develop without warning and be tough to spot.
More than 80 percent of all lifeguard rescues in the U.S. stem from swimmers caught in rip currents.
If caught in a rip current, the best response is to ride it beyond the surf zone and then swim parallel to the beach to escape its pull — but for inexperienced swimmers, the combination of panic and lack of awareness often proves fatal.
In many cases, swimmers attempt to swim against the current, exhausting themselves and draining their ability to survive.
In October 2019, well-respected NOAA scientist Bill Lapenta died after drowning in rough seas at a North Carolina beach. The National Weather Service had been warning of an increased threat of rip currents associated with the offshore passage of Hurricane Lorenzo. His death hit the agency hard.
Since then, NOAA has doubled down on efforts to educate the public about the dangers of rip currents, but only recently announced the launch of its new model.
Greg Dusek, a senior scientist at NOAA’s National Ocean Service, created the model himself, which was born from a research project he undertook while a graduate student at the University of North Carolina at Chapel Hill in 2007. At the time, he was working with lifeguards on the Outer Banks to collect data that would be integrated into his model.
“When I finished school and started at NOAA a few years ago, we started the process to get it operational,” he said. Part of that meant waiting for technology to catch up.
“We didn’t have the modeling capability to provide the input we needed,” he said.
The new rip current model ingests data from NOAA’s Nearshore Wave Prediction System, an ocean forecasting model that was upgraded in January. That upgrade made it possible to apply Dusek’s methods.
“We’re now providing an hourly forecast, and since rip currents are influenced by the tides, we capture that variability,” Dusek said. “If the likelihood [of rip currents] is going to change throughout the day, we can tell you that. We’re able to provide about a kilometer resolution along shore.”
That means two neighboring beaches would receive different, custom forecasts. Before, the National Weather Service issued blanket forecasts that could span 100 miles or more.
To improve the model’s accuracy further, NOAA partnered with the United States Lifesaving Association, a nonprofit group representing lifeguards, to collect observations of rip currents and learn more about them.
Dusek explained that the improvements in the models will equip beachgoers to make more informed decisions.
“When people are planning weekends at the beach or lifeguards are planning staffing … they’ll use this,” he said.
The next hurdle is figuring out how to disseminate the enhanced forecasts provided by this model to the people who need them. The Weather Service currently issues beach hazard or high rip current risk statements one or two days in advance. With the ability to pinpoint rip current risks six days out, the Weather Service is evaluating how to design products that will raise awareness of the impending hazard.
“How the information is going to be used and provided is still being worked through,” Dusek said.