IME, areas that get snow dump need to have shrubs that can be pruned back to the ground in really bad winters to remove the broken and bent branches to allow the shrub to regrow to its natural shape. One plant that will do this well is spirea. In good years, I just leave it. In bad years, it gets pruned to less than 6" before leaf out, and then regrows starting within a week or so, and within 3 weeks it is looking good again. My favorite spirea is 'Ogon' (occasionally sold as Mellow Yellow) which has narrow chartreuse-gold foliage. The smaller Hydrangea paniculatas would probably be OK with severe pruning, though not below a foot or so, but in good years wouldn't exceed 3'-5' depending on the variety, and all can be pruned for size. Check out H. paniculata Bobo, Dharuma, Little Quickfire, and Little Lime. Little Quickfire, Bobo and Dharuma should start blooming in late June or early July for you and continue pretty much through fall, which flowers starting white and slowly changing to various shades of pink as they age. Other than that, I can't think of any shrubs off the top of my head that will both enjoy the west exposure and tolerate the snow dump. IME, lilacs will sustain a lot of damage with heavy snow, Weigela will be misshapen, and though I don't have a Deutzia in a snow dump area, I find the branches delicate enough so that I don't think that they would tolerate the heavy snow well. Hopefully someone else will have experience with some shrubs that will be OK with hot sun and snow dump.

For the rest of your plants, I would look at some of the more substantial perennials that would be large enough to substitute as shrubs, but not mind the western sun in summer and since they die back to the ground in winter, the snow wouldn't be an issue. Look at Baptisia (I particularly like 'Carolina Moonlight', 'Purple Smoke', and the species B. australis), Amsonia hubrichtii, some of the larger fall asters such as Aster Laevis 'Blue Bird', Veronicastrium, some of the shorter clematis such as Piilu (AKA Little Duckling) or Justa, both of which are only 5'-6', but can be grown shorter by using a 4' trellis and letting it spill down from the top. Oriental/trumpet-cross lilies (I've seen them called orienpet lilies) seem more resistant to red lily beetles IME, and are available in various heights.

Honestly I don't see anything in the description that makes this area difficult. Most plants are asleep in the winter, so lack of sun then isn't a big problem. What kinds of plants do you like? Ornamental, food producing, privacy? Diablo Ninebark is tough and can be pruned to the ground...it's native to New York. Holly has winter and wildlife interest and is easy to establish. Few shrubs truly have a "max height" but these can be pruned to the height you like. Mountain Laurel is hard to establish and might dislike the summer heat but it's an evergreen with great flowers. Rhododendrons are an obvious choice. You could stick hydrangea near the water spigot, where you can easily water them.

The tricky part isn't the light levels since as Ed said it's the light levels in the growing season that matters, in this case full sun (more than six hours.) Instead it's the snow dump that makes it tricky. You don't want spring flowering plants since if you need to prune the flower buds will get removed. Some rhododendrons may be ok with snow dump but mountain laurel (Kalmia) won't do well with snow dump or full western sun IME. Hydrangea macrophyla or H. arborescens won't like southwestern sun though H. paniculata is fine in full sun. One of the smaller ninebarks may work but Diablo is too large for a 4'x4' spot. Look at Tiny Wine instead.

Miscanthus 'Silver Grass' is one recommendation. I've planted two at the corners of a walkway I have which abuts a drive. It has 2-5' of snow shoveled on top of it throughout the winter time but grows back vigorously each year. I keep the foliage on through winter, loosely tying up the plant to maintain its structure and winter beauty, cutting it down about 4" from the ground once the ground thaws in spring. This will surely tolerate being mounded with snow, in my experience. Miscanthus likes to grow into massive clumps, and will fill the bed while also hiding the gravel edge along the house.

I too recommend Spirea, which can be literally mowed to the ground and will healthfully regrow. Some varieties will be branching, tree-like shrubs, like Vanhoutte. This has a nice dark green foliage with white flowers. There are others as mentioned above that have bright, chartreuse foliage with pink flowers. These grow more like wide bushes and might fill the horizontal space better than taller varieties.

Ideas that aren't shrubs:

Asparagus would be an interested option for this spot. They're dormant from mid summer until early spring, so snow dropping is no issue. The difficulty would be establishing the bed (takes 3-5 years) but would be a beautiful foundation planting, as well as an edible one.

A client grows ornamental Fennel along her foundation with similar results, but this likes to seed itself if you leave aren't dead heading regularly. It gets to be about 4-5', has beautifully lacy, light foliage with yellow florets.