A “potentially historic” geomagnetic storm is forecast for this weekend and it appears Utahns might be able to catch a glimpse of an aurora borealis from it.

The Space Weather Prediction Center, a division of the National Oceanic and Atmospheric Administration, issued a Severe (G4) Geomagnetic Storm Watch on Thursday, something it last did in January 2005. The alert states at least five coronal mass ejections — large expulsions of plasma and magnetic field from the sun — are expected to reach Earth between Friday and Sunday.

"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 agency wrote.

A G4 storm is the second-strongest on the center's geomagnetic scale. The solar expulsions can potentially disrupt communications, as well as other technologies like the electric power grid, navigation, radio and satellite operations, the center wrote on Friday.

Clinton Wallace, the center's director, said it's "an unusual and potentially historic event."

It'll also create a strong aurora borealis — also known as the northern lights — that could be visible for many parts of the U.S. this weekend, including in Utah.

KSL meteorologist Matt Johnson says 11 p.m. Friday to 3 a.m. Saturday is shaping up to be the best opportunity to view the celestial event, especially in the extreme parts of northern Utah, based on the solar forecast.

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It helps that it may be less cloudy in the region during these times.

The National Weather Service forecast calls for 10-25% cloud cover throughout most of northern Utah late Friday and early Saturday. Various spots near the Wasatch Front may reach 35-45% and heavier cloud cover is possible in parts of southern Utah.

The northern lights occur when the sun's ejections reach the Earth's magnetic field, causing the solar ions to glow in a visual spectacle, as noted by the National Weather Service. The events are more common in areas closer to the North Pole, such as Alaska and Canada, but larger storms — such as the one forecast this week — can travel farther south.

Idaho, Montana, Oregon, Washington and Wyoming appear to have stronger viewing odds among Western states within the Lower 48 from the latest geomagnetic storm. The Space Weather Prediction Center wrote states as far south as Alabama could be in luck this weekend.

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