‘Severe’ Geomagnetic Storm Means Aurora May Be Seen In Southern States

Space weather forecasters have issued a severe, G4-level geomagnetic storm watch, only the second of that severity in 20 years, after a strong X-class solar flare and coronal mass ejection that could push the aurora borealis as far south as Alabama Thursday and Friday.

Forecasters with the Space Weather Prediction Center, a division of the National Oceanic and Atmospheric Administration, said in a news briefing Wednesday that the CME, carried to Earth by fast-moving solar winds, was due to arrive Thursday morning or midday Eastern time. The CME arrived as predicted

The storm watch alert says the aurora may become visible over much of the northern half of the country, and maybe as far as Alabama and northern California.”

Geomagnetic storm alerts are rare. In May, NOAA issued a similar statement about the strong solar storm that produced the strongest aurora display in perhaps hundreds of years. The aurora was visible widely in the United States, including in places near the southern border, and around the world.

Aurora chasers in places that don’t usually see the northern lights have been busy this year as the sun approaches “solar maximum,” the point in its 11-year cycle when the sun is most active.

Officials with the Federal Emergency Management Agency have been notified of the potential for communications glitches as well as disruptions to the power grid. Utilities in the North American power grid also have been notified. Both are standard protocol with any geomagnetic storm of this level but are especially vital as FEMA responds to back-to-back hurricanes Helene and Milton battering the Southeast.

“What Florida has going for it is its latitude,” space weather scientist Rob Streenburghsaid, explaining the CME would have to be exceptionally large for the energy particles to dip that far south. “That adds a little bit more to our comfort level.”

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Still, with power still disrupted with Helene and more outages likely with Milton on a national power grid that is interconnected, officials were reluctant to say it would pass without notice in hurricane-ravaged states.

“We don’t know yet what this storm will bring us,” space weather forecaster Shawn Dahl said Wednesday.

The geomagnetic storm in May caused the sensors in some farm equipment to fail, idling farmers during a busy planting season. “It cost a lot of money,” Streenburgh said.

Farmers again are in the fields for harvest as the CME arrives. “They have contingency plans,” he said, noting that about 5,000 satellites have since been adjusted.

The effect of the G4 storm isn’t expected to be anything close to matching the intensity of the Carrington Event, an 1858 solar storm that spewed electrified gas and subatomic particles toward Earth, causing telegraph lines to spark and electrocuting operators. The northern lights danced around the globe, extending as far south as Jamaica.

A geomagnetic storm in 1989 that caused the electrical grid to collapse in Quebec, Canada, was about three times smaller than the Carrington Event. The storm also damaged a transformer in New Jersey, leaving 5 million people without power for nine hours.

Today, a geomagnetic storm of the intensity of either event would affect far more than telegraph wires and could be catastrophic given the dependence today on things controlled by satellites and other systems that can be affected.

The geomagnetic storm is ranked a G4 on a scale of 1-5, and the Kp Index, the measure of auroral strength, is 8 on a scale that tops at 9. A Kp index of 5 is generally required for the aurora borealis to be visible.

The X1 flare that produced it isn’t nearly as strong as the X8.7 flare in May that made the aurora visible in areas along the southern U.S. border, or the more recent even stronger X9 flare that produced northern displays in about a third of the country this week.

The difference, Dahl explained, is that it was a long-duration solar flare that erupted from the center of the sun and is being carried to Earth extremely fast at 2.5 million miles per hour.

Dahl said space weather forecasters “never know for sure” when the aurora will be visible. If the geomagnetic storm progresses to a G4 level, “we’re talking about the aurora much farther south.”

He noted that today’s technology allows cell phones to pick a red aurora “much farther southward than you think it would be visible.”

“Lady Aurora,” as some people have begun to call the shimmering curtains of pink, red, green and yellow, is fickle. Strong solar flares and high Kp indexes don’t always translate to light displays.

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.”

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.