From South Africa With Love

If you surfed between South Carolina and Maine the past two days, thank a Saffa.

Well, maybe not a Saffa, but a South African storm. In a extremely rare event, researchers at the Army Corps Field Research Facility in Duck, NC are tracking an unforeseen pulse of waves from as far north as Maine all the way back to a storm that swirled between Cape Town and Antarctica — more than 13 days ago. A two-foot swell that, despite traveling 13,000 miles, still slipped past everyone, catching both surfers and forecasters off guard. Sure, it was nothing huge — waist- to chest-high max. But when a clean, 17-second, six-wave set pops up out of nowhere in June on the East Coast, it's time to ask questions. Especially if you're Army Corps Research Oceanographer and surfer Dr. Jeffrey Hanson. We decided to check in to see what more we could find out about this unique phenomenon. The best news of all? "It's dropping – but waves should keep arriving for a couple more days."

SURFINGMAGAZINE: When did you realize this pulse was coming all the way from Africa? And why did all the forecasts miss it?

DR. HANSON: Well, we figured this out yesterday in coordination with Oceanweather, Inc. Our measurements indicated he origin of this swell to be off of South Africa about 13 days ago. Oceanweather confirmed there was a fairly major winter storm at that time and location. And the key is, forecasts rely on wave models; what we do is look at real data as it arrives. And the wave models predicted this storm to be really weak. I checked Surfline and all the local surf forecasting sites yesterday, and there was no indication that this was happening. All thumbs down. The actual data determined it was much stronger.

So you see a real swell as it happens, then backtrack to see how and where it was generated.

Exactly. So we called Oceanweather to confirm there was a storm in that location. And there was on May 28. So it's coming from over 13,000 km over the past 13 days. That means, long period, high energy. The period's down to about 15 seconds now, but it started at greater than17 seconds. So these waves are still arriving here, and they will be for a few more days, because longer waves travel faster than short waves so they get spread out. And that's what we measure —that spread — to determine how far they travel and where they were generated. But it's important to note this is a real unusual opportunity because the ocean's so calm right now. No other systems are out there. So it's easy to read what's essentially a really weak signal.

How weak was it?

Only about two feet. But it's like a tsunami in a way that it's only a couple feet high before it reaches the bars, but the slow period makes it shoal up pretty nice. We've seen chest-high waves here in Duck. And there were actually a number of lifeguard rescues yesterday — my son Jason made two rescues himself. And he said the rips were forming very 15 to 20 min, same as the sets, which is pretty amazing. He also said he had the best skim session of his life Tuesday night. [laughs]

Who else is seeing waves from it?

They're just starting to see it in Maine. So for sure from Maine to North Carolina. I'm guessing South Carolina, as well. Below that, it's probably blocked by South America.

Have you ever witnessed this type of event before?

Nothing like this. I might see waves from the South Atlantic once a year. Normally they 're off of West Africa, off South America, a bit below the equator. This event's coming from way down, almost 50 degrees south. Between Africa and Antarctica. That energy traveled 13 days to get here. That's pretty awesome for the Atlantic. And what's also incredible is the red dot we put on the map is a perfect fit for where it started. But, again, it may happen more often and we just don't know. The only reason we can see it so well is there's nothing else out there. All that background clutter's been removed at the perfect time. So it's basically like everything aligned. It's a real treat for us as scientists. And surfers. And it's sure making the skimboarders ecstatic.