It was cold this morning (about -25°C/-13°F) but she was plugged in all night. Started like a chanp like she always does. Then, a couple miles up the highway (after letting it idle for 5 or 10 minutes), this strange sound comes out of nowhere and comes and goes. About 30 minutes of driving later, the sound disappeared entirely. Power steering fluid is full and the accessory belt looks fine. I'm thinking it's something to do with the transmission being cold. Thoughts?

Here is the video:

 

Was your radio on?

 

No, I had it turned off so I could hear the strange sound better. I thought it might be interference, but that doesn't seem to be it. FWIW, it went away and never came back, so for now I'm gonna chalk it up to the cold engine/tranny ¯\_(ツ)_/¯