This is a classic Chinook Arch in southern Alberta.
Briefly, moisture-laden air flows strongly from west to east toward the Rocky Mountains. As it blows it is lifted by the mountains. This causes a lot of moisture to be dumped on the western slopes, and the air dries out.
On the eastern slopes the air – which is now flowing even more strongly by virtue of Bernoulli’s Principle – descends quickly, and this causes it to dry out even more. The dry, warm air passing over snow packs east of the mountains causes those snow packs to melt and evaporate very quickly.
These cloud formations are what happens east of the arêtes when the air starts to descend. A Chinook Arch like this can be traced from south to north – almost as far as the eye can see.
Chinooks mean warm air for southern Albertans. For us they create a welcome respite to the long, Canadian winter.