Just a heads up from Duluth, Minn. The Kp index hit “5” at 9 o’clock tonight and the northern lights are putting on a modest show as of 10 p.m. CDT. We have high clouds moving in, but a chunky green arc with a few active rays are sliding around low in the northern sky. The ray tops are reaching about 20 degrees (two fists held at arm’s length); the arc’s about 10 degrees up. There’s a fair amount of movement, but you’ll need to get out of town to a place with a good northern horizon to appreciate it.