SALEM, Ore. — One moment, Jayson Thomas was on the Oregon beach with his 3-year-old son. The next, they were gone, swept away by a “sneaker wave” as his wife looked on.

The man and his boy were but the latest to be lost to a sneaker wave, which are prevalent in the Pacific Northwest. A leading expert says there needs to be greater awareness to prevent future tragedies.

In fact, Tuba Ozkan-Haller of Oregon State University has just finished the first year of a three-year research project to devise a sneaker-wave early warning system, a project funded by the National Science Foundation. She hopes the warnings will be sent out by the National Weather Service.

The seas off Cape Blanco were not particularly rough on Sunday afternoon when Thomas, his wife and their son, who lived near Eugene, were on the beach, Ozkan-Haller noted.

But appearances can be deceptive.

“People make up their minds about how safe an area is pretty quickly, after watching the beach for five minutes,” Ozkan-Haller said Tuesday in a telephone interview from Corvallis. “That doesn’t give you the information you need to assess that an area is safe.”

While the weather might be fine, a storm far out to sea, even across the Pacific, often generate such a wave. As it moves through the broad surf zone and over the gentle slope approaching Oregon’s coast, one wave can catch up with another, combining forces and allowing it to run up further on the beach, said Ozkan-Haller, who is with OSU’s College of Earth, Ocean and Atmospheric Sciences.

Six years ago, a sneaker wave knocked two high school students from Eugene off a rock near Yachats, sending them into the turbulent waters where they drowned.

Stormier winter weather produces more sneaker waves, Ozkan-Haller said.

The Oregon State Police said Thomas’ wife, Charity Woodrum, was an arm’s distance away when her husband and her son were struck by the wave. Witnesses indicated the two were the only ones who were hit, said Oregon State Police Capt. Bill Fugate.