Powerful sun storm could bring northern lights to parts of US on Wednesday

FILE - The northern lights over Arabaer near Selfoss in the south of Iceland. (Owen Humphreys/PA Images via Getty Images)

Space weather is happening all the time, and if you are lucky enough, you might catch a glimpse of the aurora borealis over the Northern Hemisphere this week.

NOAA's Space Weather Prediction Center (SWPC) predicts a moderate geomagnetic storm on Wednesday due to a coronal mass ejection (CME) observed late Sunday. The office issued a Geomagnetic Storm Watch to the G2 level Wednesday and G3 level for Thursday.

The northern lights are primarily seen in the higher latitudes in Alaska or Canada, but they have also been seen farther south in California, Nevada and even Texas during significant solar events.

This midweek event is expected to be much weaker than the severe geomagnetic events that happened in late April and March.


If strong enough, space weather could have significant impacts on power grids, aviation, satellites and oil and gas industries, said Lt. Bryan Brasher, a project manager with the SWPC. 

The agency is on watch 24/7, observing and forecasting the space weather environment to allow these key parts of Earth's infrastructure to take mitigating actions to protect their equipment and services.

Will I see the aurora tonight or tomorrow night?

The SWPC classifies geomagnetic storms from G1 (minor) to G5 (extreme). The greater the G number, the farther equatorward you can expect to see the aurora, according to Brasher.

"If our forecast for a G2 (Wednesday) holds to be true, I wouldn't expect to see aurora south of any state that borders Canada," he added. "If, however, we experience a G3 or even G4 storm, you could expect to see aurora at much lower latitudes."


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Here's a look at Wednesday night's aurora forecast.  (NOAA Space Weather Prediction Center)

As of Wednesday morning, there were no Geomagnetic Warnings in effect.

"We do have a couple of recent alerts and warnings related to other space weather phenomena that mainly affect radio communication," he said.

A watch is issued when it's believed there will be a risk of significant space weather, but the occurrence or timing is uncertain. A warning is issued when space weather is occurring, imminent or extremely likely based on model data or observation-derived calculations. An alert is issued when a space weather event has already started.


The more overhead the aurora, the more of it someone could see.

"Based on the fact that aurora typically occur up to 250 miles above the surface of the Earth, it should be possible with the curvature of the Earth (with no light pollution and marginal cloud cover) to see the aurora low on the northern horizon up to 800 to 1,000 miles away," Brasher said.

However, in areas of even moderate light pollution, seeing the aurora might only be possible through long-exposure images, Brasher added.

"Long exposure may also make aurorae visible south of the 800- to 1,000-mile boundary," Brasher continued. "When you are that far south, you may only see the reddish 'tops' of the aurorae (vs. the characteristic green bands visible in the pictures we've all seen taken from above the Arctic Circle)."


Space weather happens all the time

We've had two G4 storms in the last few months, and we will likely see more soon, according to Brasher.

So while even if Wednesday's storm isn't big, Brasher said you can expect with a high level of certainty that we will have a few more before this solar cycle is done. However, to see the aurora in New York, Brasher said a G3 or greater storm is required.

Yet if you live in the suburbs, Brasher said you aren't likely going to be dark enough to see the aurora. If you know a storm is coming, go north while getting as far away from city lights as possible and avoiding cloud cover.

Historical data shows that one could expect about 60 G4-level storms and four G5-level storms per 11-year solar cycle. 

"This is, of course, an average, but G5 storms are quite rare," Brasher said. "The last solar cycle was rather mild, but solar cycle 25 is already on its way to being much more active.  

According to Brasher, space weather is intimately tied to activity on the sun. Activity on the sun goes through 11-year cycles during which the magnetic field goes from being very uniform to very tangled and chaotic, then back to uniform after the magnetic field of the sun flips.

"Sunspots and, therefore, solar activity is greatest when the magnetic fields are all tangled and chaotic, and we expect to hit peak activity sometime in the next few years," Brasher said.

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