The city of Saskatoon is located in potash country, meaning unit potash trains, and subsequent light power moves from the mines to the city, are a common site. Whenever possible CP likes to tag the potash power onto a manifest, in addition to wayfreight power (typycilally Geeps) which work grain slidings as well as the potash mines. On this day CP 456 managed to pick-up both power sets and is bringing them back to Sutherland.
Cathing the train itself was a bonus, since he normally runs at night.
PS. One of the city's busiest HWY's, Circle Drive, which turns into the Saskatoon-Regina HWY, is in the foreground, cropped out of the photo. The University of Saskatchewan experimental crop field next to it, is what you see at the bottom.