Tonight's northern lights are visible in Yellowknife, Canada. Here's a snapshot from the AuroraMAX HD camera. (Tonight is Monday, November 12, 2012.)
Some evidence of sightings:
The Twitter account @Aurora_Alerts is active when the Northern Lights are active, and it gives very short term forecasts of activity. The higher the Kp number, the brighter the aurora.
The Twitter account @AuroraMAX belongs to the night sky camera that took the snapshot above. It is run by the Canadian Space Agency, and their (English language) homepage has more information about their setup.