Three-day geomagnetic storm finishes hitting Earth today, but what threats remain?

A three-day geomagnetic storm watch, which began on Monday, will wrap up today.

The storm is the result of eruptions of plasma from the Sun, called coronal mass ejections, or CMEs. These CMEs travel towards the Earth, and when they hit the Earth's atmosphere, they can create dazzling auroras. Auroras from this latest storm made it as far south as the Pacific Northwest. 

While we won't see the Northern Lights as far south as the Coachella Valley — like we did during the severe geomagnetic storm earlier this May — geomagnetic storms can still pose risks. Satellites, GPS, electrical systems, and more can experience disruptions from these storms.

But the National Oceanic and Atmospheric Administration's Space Weather Prediction Center keeps tabs on the Sun and other space weather events to warn power companies and government agencies about potential threats.

Shawn Dahl, the Service Coordinator with NOAA's SWPC, says they were able to warn power companies in the hours leading up to the geomagnetic storm in May.

"We call them about that kind of activity so they can try to mitigate the problem because it develops, it sends off alarms and causes overheating on their equipment, which if they don't account for it, can cause a massive power outage. It could affect hundreds of thousands of people. That's why we do what we do," Dahl explains.

Experts emphasize that folks shouldn't worry as they live their day-to-day lives, though. Local astronomers, like Eric McLaughlin of the Rancho Mirage Library and Observatory, "We've had one event in recorded history that was concerning, and that was the Carrington Event. And that did involve some power lines in particular, also telegraph lines supposedly did catch fire, but we haven't had anything that dramatic since."

The latest geomagnetic storm watch is set to expire after today. NOAA says the past two days have been weaker than expected, though we could see conditions at G1 (minor) or near G2 (moderate) tonight. NOAA's geomagnetic storm scale range from G1 (minor) to G5 (extreme).

NOAA provides more information online about the threats that geomagnetic storms pose.