Rare Solar Storm Alert Issued for This Weekend

WASHINGTON — An unusually severe solar storm could cause communications and electrical disruptions this weekend as solar flares reach the Earth, forecasters from the Space Weather Prediction Center said on Friday.

Forecasters with the agency, which is part of the National Oceanic and Atmospheric Administration, said a very large sunspot cluster has been producing moderate to strong solar flares since Wednesday.

The marked increase in the severity of these flares finally pushed forecasters to issue a very rare “G4 storm watch” for the planet Friday morning.

The designation pegs this weekend’s event as the most powerful solar storm the agency has tracked in nearly 20 years.

Sean Deahl, service coordinator for the Space Weather Prediction Center, said the sunspot cluster responsible for the current activity is “one of the largest and more complex ones we’ve seen in this solar cycle.”

He noted that solar storm watches are denoted on a 1 through 5 scale, with the “G” standing for “geomagnetic.”

“Designating this a G4 event means we have a high confidence that we’re going to see a series of coronal mass ejections, which are blasts of energetic particles,” he said.

Despite this, Deahl said, forecasters still don’t know how severe the impact of the solar storm will be on Earth.

“We won’t know that until the coronal mass ejections arrive at the NASA ACE satellite and the Discover NOAA satellite, which are both located about a million miles from the Earth,” he said. “Once they do and we have more certainty, that’s when we’ll be able to issue warnings to utilities and other entities that are likely to see impacts.”

NOAA defines coronal mass ejections, also known as CMEs, as eruptions of solar material that can cause geomagnetic storms in the upper Earth atmosphere.

Forecasters said when and if they do, sometime between late Friday or early Saturday, they could touch off an aurora visible as far south as Alabama or northern California. 

“As far as the worst situation-case we might expect here on Earth, that’s tough to say,” Deahl said. “I wouldn’t want to speculate on that. However, severe levels are pretty extraordinary. It is a very rare event to happen. 

“So it is important that we notify critical infrastructure operators — those who work in communications, the electric power grid, navigation, radio and satellite operations — so that they are adequately prepared to spin up procedures and make sure alternate equipment is working and lines are at their top notch.

“But the key element here is that they know what’s causing anything, so that if a situation unfolds, they’ll be able to take the proper steps to help mitigate and control any developing problems,” he said. 

The most famous — and intense — solar storm in history is the so-called Carrington Event, which occurred on Sept. 1 and 2, 1959.

Its beginnings, a very bright solar flare, were observed and independently recorded by two British astronomers, Richard Christopher Carrington and Richard Hodgson. So powerful was the blast that it took the coronal mass ejection only 17 and half hours to reach the Earth, rather than the three or four days which is typical,

The resulting geomagnetic storm created vivid auroral displays around the world and caused fires up and down the then-nascent telegraph network.

Amazingly, two telegraph operators, one in Portland and one in Boston, were able to turn off the batteries to their equipment and operate for more than two hours on the electricity the storm pumped into the system.

Dan can be reached at [email protected] and at https://twitter.com/DanMcCue