Northern Lights Could Peek Into Wisconsin Friday Night

WISCONSIN — Forecasting aurora borealis is an imperfect science, but much of Wisconsin might just be in for a holiday treat from the northern lights Friday night amid the icy grip of a windy winter storm.

Just a handful of northern states including Wisconsin could see the aurora borealis Friday evening after a geomagnetic disturbance, according to the National Oceanic and Atmospheric Administration's Space Weather Prediction Center. As nighttime nears, be sure to check the Aurora — 30-Minute Forecast page from the NOAA's space forecasting arm.

Northern lights displays are never guaranteed, of course, but if it happens, it would be a treat for northerners hardy enough to brave the winter storm unleashing wicked winds that are sending feel-like temperatures far into the subzero territory.

The view line for Friday night's aurora extends into Wisconsin, but leaves much of the southern parts of the state out, according to NOAA. So, if you're hankering for a shot at viewing the northern lights, you probably have the best chance if you're further north.

Chances also likely rely on weather conditions and visibility, which may be less than favorable in Wisconsin considering the National Weather Service expects blowing snow in much of the state with a winter storm warning in effect until Saturday morning.

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The geomagnetic disturbance early Friday morning treated people in Fairbanks, Alaska, and Tromso, Norway, to auroras. More disturbances are expected Friday night, and that could result in aurora activity in the northern U.S., according to NOAA’s forecasters.

The auroras may also dance on Christmas Eve, too, though the latest forecast showed the northern lights viewing area Saturday will more likely be far north of the U.S.-Canada border, a fairly typical occurrence.

Auroras don’t have to be directly overhead to be observed, NOAA explained, but can be seen by as much as 620 miles away if the lights are bright enough and conditions are right.

The science behind the aurora borealis is complicated. It starts with a blistering hot sun, whose surface is about 6,000 degrees Fahrenheit, but whose atmosphere, or corona, is about a thousand times hotter — so hot the sun’s gravity can’t hold it in place.

Because of that, the sun ejects a continuous stream of plasma — charged particles of electrons and protons known as a coronal mass ejection, or CME, carried by solar wind. At a temperature of about 1.8 million degrees Fahrenheit, it flows outward through the solar system at speeds as high as 900 kilometers per second.

Solar wind is what blows the tails of comets around, and it’s visible as a halo around the sun during an eclipse. When solar winds are directed toward Earth, the CMEs collide with the gasses in Earth’s upper atmosphere in what’s called a geomagnetic storm, creating the potential for aurora displays.

For anyone who wants a deeper understanding, The Conversation has an easily understood explanation of the relationship between charged solar particles and auroras, and the role of magnetic reconnection.

This is a particularly active time for the solar storms that produce northern lights displays. That’s because we’re midway through an 11-year cycle in which the sun’s magnetic fields flip polarity — and that means the northern lights could dance more often in the next decade or so.

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The chances to see the northern lights increase as the 11-year solar cycle enters what’s known as “solar maximum,” when sunspot activity increases 93 million miles from Earth. Aurora experts say the busy season for sunspots should peak between 2023 and 2028.

Aurora strength is measured by the Kp index, according to the Space Weather Prediction Center. In general, the chances of seeing the lights are best with a Kp index of at least 5. With a Kp index of 9, the auroras can be seen as far south as St. Louis, Missouri.

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Polar latitudes see the northern lights about half of the nights of any given year, according to NOAA. In Fairbanks, Alaska, the aurora season runs from Aug. 21-April 21. The lights can typically be seen there an average of four out of five nights when the sky is clear and dark enough.

The auroras dance frequently enough in northern states in the continental U.S. that many have developed aurora borealis tourism. Besides Alaska, other U.S. states that most often see northern lights are Washington, Idaho, Montana, North Dakota, Minnesota, Wisconsin, Michigan, New Hampshire, Vermont and Maine.