'Severe' Geomagnetic Storm Could Send Northern Lights Over CA

CALIFORNIA — The Golden State may catch a glimpse of the northern lights Thursday night as another powerful geomagnetic storm ripples through the Earth's atmosphere.

The latest disturbance is courtesy of an X-class solar flare that fired off from the sun Tuesday, which was due to make contact with Earth by midday Thursday. The National Oceanic and Atmospheric Administration's Space Weather Prediction Center (SWPC) issued a G4 (Severe) geomagnetic storm alert Thursday afternoon.

G4 storms are second most intense on NOAA's five-point scale and can prove powerful enough for the aurora borealis to be seen by the naked eye in parts of Northern California and visible to cameras and smartphones even further south.

"That estimation right now would be if we get into the nighttime here in the United States, and this storm continues to progress as a G4 as anticipated, then we're talking about the aurora being much further south than those northern-tier states," said Shawn Dahl, a service coordinator for the Space Weather Prediction Center. "So, if we get to that level, this could easily be seen down through the central Eastern states, into the lower Midwest, and even into Northern California. That's just the furthest south we know it could go to at that level, it can certainly be further south than that."

An aurora forecast shared by the University of Alaska Fairbanks' Geophysical Institute showed promising signs of strong aurora activity hanging on into the nighttime hours Thursday.

Dahl said there was a 25 percent chance the storm could reach G5 (Extreme) levels, carrying the potential to become another "global phenomenon," like in May when the northern lights were widely visible across the United States.

Even though it arrives in the day, the strongest effects of a CME's "magnetic cloud" can take a few hours to materialize.

Mike Bettwy, the head of the SWPC’s forecast office, said aurora chasers are usually rewarded within a couple of hours after nightfall. Patience is a key, he said.

“The key is the magnetic orientation,” he said. “It’s remarkable how quickly the aurora can shut down and diminish, and just as quickly return.”

For the best chance of seeing the aurora, the SWPC recommends getting away from the city lights and finding a vantage point with an unobstructed view facing north. Under the right viewing conditions, like on a dark hilltop, the aurora can be seen even when it is hundreds of miles away. The northern lights are typically most active between 10 p.m. and 2 a.m.

If the aurora doesn’t materialize in the lower 48 states this time around, there are plenty more chances for people to see them. Solar Cycle’s 25 solar maximum may not occur until early 2025, and even 2026 could be a busy year for solar activity.

Activity this solar cycle has surprised space weather scientists and forecasters. Solar Cycle 25 is the most active on record, and they’re not quite sure why.

“It’s one of the many mysteries to unravel,” Dahl said.