The night the aurora finally reaches your sky, you don't want to hear about it the next morning. Aurora Forecast: Borealis tells you, in plain language, whether it's worth stepping outside tonight, and alerts you the moment the lights are likely overhead and the sky is dark where you are. If you've ever chased the northern lights, you know the routine: a dozen browser tabs, a "Kp" number that means nothing without a decoder ring, three apps that disagree, and the quiet fear that the best…