Hey! I'm still new to this but I'm in MN and this past snowstorm my girls did the exact same thing. Seen the snow and said NOPE!
I added/made 2 feeders for inside the coop, gave them extra greens on the cold days to pack away at, and put straw down. Once straw was down they came out and in turn them exploring melted/ moved the snow. So even just a couple handfuls of hay could get em out and and moving to then clear more.
IMO, if I had your current setup I would enclose the underside of the coop on 2 sides with a tarp/shadecloth/plastic/ or anything to just stop the snow. Then if it snows just drop a tiny bit of hay or chips or something down under their ramp amd they could come outside and at least go outside the coop out of the snow.