We have a coop with a similar design, details here:I built a hoop coop for mine. It's great for guineas because it's 10 feet tall. Details of the build in the Thread, Helpful Hints for building coops. I have birds in it year roundView attachment 2272879
https://www.backyardchickens.com/threads/modified-hoop-coop-design-development.1120946/
However, we are much warmer than you so I’m not sure if just a tarp would be enough protection where you are. I also don’t know if the snow would slide off or accumulate and collapse it. Currently, the guineas free range for part of the day but stay in the run for at least half of the day. I’ve used the run much more than I expected I would. We currently have a 20x40 ft run made from electric poultry net and hawk netting. This run has been rather problematic and so I’m wondering about converting to a wood and wire run.
Edited to add: I am really sorry that you lost your birds to predators recently! I get really attached and find it heart breaking to lose them.