STEAMBOAT SPRINGS, Colo. — The northern lights, or aurora borealis, are forecast to put on a celestial show across Canada and the northern United States this weekend.
The NOAA Space Weather Prediction Center issued a G4 Severe Geomagnetic Storm Watch for Friday through Sunday, the first time an advisory of that magnitude has been issued since January 2005.
A solar outburst reached Earth on Friday afternoon, hours sooner than anticipated. The effects were due to last through the weekend and possibly into next week.
"This is an unusual event," the Space Weather Prediction Center said in its advisory, adding the phenomenon causing atoms in the upper atmosphere to glow green and gray.
"Several strong flares have been observed over the past few days and were associated with a large and magnetically complex sunspot cluster, which is 16 times the diameter of Earth," the advisory said.
States in the forecasted zone to see the northern lights include Washington, Idaho, Montana, Minnesota, Wisconsin, Michigan, Vermont, New Hampshire, North Dakota, South Dakota, New York and Maine.
Northern Colorado, Wyoming, Nebraska, Iowa, Illinois, Ohio and Pennsylvania are on the edge of the area that is likely to see a visible aurora borealis on the horizon. But it was hard to predict, and experts stressed it would not be the dramatic curtains of color normally associated with the northern lights, but more like splashes of greenish hues.
Whether parts of northern Colorado could see the northern lights depends on if clouds clear to create clear skies. The best potential to spot the aurora borealis is further north and east in the state.
The sun has produced strong solar flares since Wednesday, resulting in at least seven outbursts of plasma. Each eruption — known as a coronal mass ejection — can contain billions of tons of plasma and magnetic field from the sun's outer atmosphere, or corona.
The flares seem to be associated with a sunspot that’s 16 times the diameter of Earth, according to NOAA. It's all part of the solar activity that's ramping up as the sun approaches the peak of its 11-year cycle.
This storm — ranked 4 on a scale of 1 to 5 — poses a risk for high-voltage transmission lines for power grids, not the electrical lines ordinarily found in people's homes, said NOAA space weather forecaster Shawn Dahl. Satellites also could be affected, which in turn could disrupt navigation and communication services here on Earth.
Photographing the aurora borealis
Photographers say the aurora borealis looks much dimmer to the naked eye in Colorado than it appears in photographs.
The key is to get a camera that allows you to adjust the length of time the iris is open during the capture. The longer the exposure, the more light there will be in the capture.
You will need a tripod when doing long-exposure photography because any movement of the camera while the iris is open will be recorded in the picture.
There has been some recent success in capturing the aurora with smartphones. Some have great low light settings or allow you to iris up a few levels manually before taking a picture.
Northern lights in Colorado
The Associated Press contributed to this report.
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