GREAT FALLS — It is never a guarantee, but we do have a chance to see the Aurora Borealis in the northern tier of the U.S., including most of Montana, on Friday night and Saturday night as G1 to G2 geomagnetic storm levels are currently forecasted (kP values as high as 6.33).
TIMING: It may be visible all night both nights, but it is currently predicted to be strongest during the first half of each night (sunset through midnight)
CLOUD COVER: Partly cloudy to mostly clear skies are forecasted for Friday night, with the clearest skies expected in northeastern Montana and along the Hi-Line east of I-15.
Mostly cloudy skies are then forecasted for Saturday night in eastern Montana, while partly cloudy to mostly clear skies are forecasted for Saturday night in central and Western Montana.
In order to get the best viewing, make sure you are as far away from city lights as possible.
Two resources for knowing when the Aurora Borealis might be visible in our area are the Space Weather Prediction Center and Soft Serve News.
The Aurora Borealis is a mesmerizing display of dancing lights in the sky. What causes this mesmerizing natural phenomenon?
It starts with the sun. The Earth is surrounded by magnetic fields. During solar storms, large masses of charged particles, or protons and electrons, are forced toward the Earth at speeds of 250 to 500 miles per second by the solar wind.
Generally, the particles are directed towards the area with the greatest magnetic activity, the poles. Upon reaching the North or South Pole, these particles interact with atmospheric gases, mostly oxygen and nitrogen. The collisions between the two cause heat, which is released in the form of light.
The color visible depends on the height of the collision. Higher altitude oxygen created a red hue, while green hues are indicative of lower altitude oxygen molecules. Pink and blue hues correlate to nitrogen molecules, the most abundant gas in the atmosphere.
In order for the Northern Lights to be visible at mid-latitudes such as Montana, the solar storm needs to be particularly intense. Brightness is directly related to the solar storm's strength. The planetary K index (Kp) is the most accurate scale for geomagnetic activity.
The Kp index goes from 1 (dim, visible only near the poles) to 9 (very bright, visible overhead in northern U.S. states). A Kp of 5 is generally seen as the threshold for a solar storm and that is when the Northern Lights are usually visible near the Canadian border.
Prime viewing for the Aurora Borealis is during the wintertime months due to the lack of daylight hours, however, it can technically be viewed any time of the year. A full moon or city lights can prohibit the brightness of the Northern Lights.
