A high-speed solar wind stream from an opening in the sun’s magnetic field called a coronal hole will arrive at Earth starting tomorrow afternoon (Dec. 1). If we’re fortunate and the zillions of electrons find their way past Earth’s magnetic defenses and into the upper atmosphere, we’ll have a modest display of northern lights.
Space weather experts are predicting a minor or G1 geomagnetic storm beginning Saturday afternoon and continuing through about midnight (Central Time). Storms like these are typically visible from the northern regions of the northern border states, Canada and northern Europe. Sometimes they fail to materialize, and sometimes they exceed expectations and expand further southward. South is good because it means more people have a shot at seeing the aurora.
If this aurora plays out as forecast, I predict that observers in the northern states will see one or two low, greenish arcs in the northern sky dappled by faint feathery forms closer to midnight. My region is under clouds for the foreseeable future — darn! But if your weather forecast is for starry skies, be on the lookout tomorrow night from late dusk to midnight. You can check the extent of the aurora at any time at the Aurora — 30 Minute Forecast site.