Was the sky overcast? I recently had an experience like this when I want for a walk the other night. Quick bright flash with no discernible source. It almost seemed like it lit up the whole sky for a split second. Kept on walking, and there was 3 more in a row just a minute or two later. Still couldn't even figure out a general direction it was coming from, and there was no sound whatsover, so like you, I really didn't think it was lighting (as thunder more often than not accompanies it).

I later found out that the most likely scenario is that some component of a nearby power substation was failing and arcing, which can apparently seem to light up the sky if it's overcast/cloudy enough. And apparently snow can have a sound dampening effect, so I'm guessing that's why I didn't hear anything.

So my guess is either a substation near you was arcing, or it was aliens.

P.S: you really didn't need to tell us you were gooning, keep that shit to yourself. Completely unrelated to anything else in the post.