I drove from Invermere to Calgary earlier this evening.... passed the Banff turnoff about 8:30 pm.
We saw a developing thunder cloud the likes of which we had never seen. It was to the west of Banff but moving away and as far as we could tell toward Calgary... sorta. Cars were parked on the side of the road all over and people were taking pictures. I would have too but the cloud still looked mostly white in places and wasn't yet ready to unleash its potential. I wanted to hit Calgary before it turned to hail.
From the highway it looked awesome, unlike anything I could even imagine. It was stacked so high it didn't look real.
I had an iphone in the car and we got a couple of snaps with that, I didn't want to stop to get the good camera out of the trunk. Here is an early picture.... and this photo doesn't do it justice.