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When winds are swells, it's rarely swell

We are big fans of your Oregon Outdoors section each Friday, and as sometimes fishers we regularly read the Fishing Report. One thing that’s made me wonder for a long time is some of the words chosen in the Ocean Outlook entry. Sometimes it refers to waves, other times swells. They appear to be used interchangeably. Are they? If not, how do they differ?

— Pat A., Medford

This question comes up every now and then, Pat, and we have come up with a swell answer from the National Weather Service.

Waves, which are more commonly called wind waves, are just that — waves directly influenced by wind. These tend to be the choppy seas actively built and maintained by winds in that area.

But they don’t stop where the wind is blowing. These wind waves keep fanning outward and eventually move out of the area where they are influenced by the winds. They shrink, tend to lose their chop, the lengths between them grow, and they continue on in a relatively consistent pattern even though there may not be a lick of wind in the air.

These rolling waves are called swells. For instance, storms off Alaska generate waves that show up off Southern Oregon as swells.

Back to the boys at Oregon Outdoors, where the conventional wisdom for interpreting the Ocean Outlook is twofold.

First, the swells will tell you how rolling the ocean is, and boaters can decide whether their craft can handle that.

But if you have a face that’s launched lunch from 1,000 ships, then pay close attention to the waves because they are the ones that produce the choppy, bouncing conditions that can leave even salty dogs queasy.

One particular double-whammy is when localized winds are creating waves in one direction while swells from a long-off storm are coming from another direction, creating pretty chaotic seas. In fact, Pat, there’s a scientific name for that — “Chaotic Seas.”

Send questions to “Since You Asked,” Mail Tribune Newsroom, P.O. Box 1108, Medford, OR 97501; by fax to 541-776-4376; or by email to youasked@rosebudmedia.com. We’re sorry, but the volume of questions received prevents us from answering all of them.