WATCH: Satellite imagery shows hurricane-like whirlpools swirling in the atmosphere along the California coast

By Tom Yulsman | July 30, 2017 12:49 pm

These intriguing features form regularly in the summer. They may look like mini-hurricanes — but looks are deceiving.


Screenshot of an animation of GOES-16 weather satellite imagery of the California coast from Pt. Reyes to the Mexican border, acquired on July 28, 2017. Please click on the image to watch the animation. (Source: RAMMB/CIRA/NOAA)

From an airplane, they can look like all the world like mini-hurricanes swirling the clouds above the ocean off the California coast — whirlpools with eye-like features in the center. Check it out:

But these vortices are actually eddies in the atmosphere, not hurricanes. They often form as winds interact with California’s rugged coastline.

Watch the animation of satellite imagery above and try to count how many are spinning between San Francisco Bay in the north all the way down to the Mexican border. I’ve circled one of them in red so you can know what to look for.

The imagery was acquired on July 28, 2017 by the new GOES-16 weather satellite, now on its shakedown cruise and scheduled to become officially operational in November.

A different satellite, Terra, spied some of the same whirlpools:


An image of the California coast captured by NASA’s Terra satellite on July 28, 2017. (Source: NASA Worldview)

Here’s an excellent explanation of the phenomenon from NASA’s Earth Observatory:

The pattern is known to meteorologists as a Catalina eddy, or coastal eddy, and it forms as upper-level flows interact with the rugged coastline and islands off of Southern California. The interaction of high-pressure—bringing offshore winds blowing out of the north—and low-pressure—driving coastal winds blowing out of the south—combine with the topography to give the marine stratus clouds a cyclonic, counter-clockwise spin. The eddy is named for Santa Catalina Island, one of the Channel Islands offshore between Los Angeles and San Diego.

The eddies tend to form quite frequently in summer. In fact, off the coast of Santa Cruz, research shows that an eddy as broad as 25 miles across forms on 78 to 79 percent of summer days.



ImaGeo is a visual blog focusing on the intersection of imagery, imagination and Earth. It focuses on spectacular visuals related to the science of our planet, with an emphasis (although not an exclusive one) on the unfolding Anthropocene Epoch.

About Tom Yulsman

Tom Yulsman is Director of the Center for Environmental Journalism and a Professor of Journalism at the University of Colorado, Boulder. He also continues to work as a science and environmental journalist with more than 30 years of experience producing content for major publications. His work has appeared in the New York Times, Washington Post, Audubon, Climate Central, Columbia Journalism Review, Discover, Nieman Reports, and many other publications. He has held a variety of editorial positions over the years, including a stint as editor-in-chief of Earth magazine. Yulsman has written one book: Origins: the Quest for Our Cosmic Roots, published by the Institute of Physics in 2003.


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