If you want a brutal but rewarding snowshoe outing, try hitting the Tank Lakes plateau in Feb!
I've been up in early April before, which is still quite a struggle from mid-way to Jade Lake and above, but after coming across a trip report from Steph Abegg she did in late Feb I decided to try for it mid-winter, for more pristine snow and heavy-coated peaks.
The East Foss Lakes TH is generally inaccessible by car in mid-winter, but you can park about 1.5 mi from it at the end of the maintained (plowed) county road (right after going under the train trestle), and hike/snowshoe to the TH.
The first 5 miles along the river were decent on the way in, several parties of the past week had laid down a bit of a trail to follow.
You can basically choose your own path in winter, just heading up the valley, but on the mid-section between the bridge (river crossing marking the end of the flat first 5 mi) to Jade Lake, you'll want to stick to the summer route as much as possible to avoid steep ravines, creeks, and cliffs.
Every snow outing is different of course, and pretty much 100% dependent on the weather and snow condition. I had 4-6" of soft pow on the way in, atop an older base that would hold my 240lb load (w/ pack) on 35" snowshoes (MSR Lighting Ascents, 30" w/ tails) with an acceptable amount of post-holing. The last two days however, it decided to DUMP. Forecast was for showers and misc breaks, but instead it dropped about 16+" in 24 hrs. My inbound tracks were completely gone, and it became a painstakingly slow and painful effort heading outbound, even downhill.
Despite the storm, it was still a beautiful trip. Complete solitude, crazy ice formations, occasional phantom sun outlines poking through the snowfall. The worst part was that despite my 3 night camp up above Tank Lakes, not once did Summit Chief, Chimney Rock, and Overcoat come out to play or be photographed (the main reason to get up there).
I think Tank would make a pretty awesome ski touring trip. It's a long 10 mi, but making turns on all that powder up there would be phenomenal! Maybe next year. Love any beta if anyone has done this before.
Notes:
- Go prepared. I wouldn't try the upper valley unless you've done it before in summer or are rather familiar (or going with someone who is).
- I had overnight temps around 0 before wind chill, I slept in a North Face Inferno 0, with heavy base layer, puffy, insulated pants and heavy socks, heated Nalgene bottle, and still got kinda cold by late morning.
- My 35" snowshoes were not enough to keep me afloat from Jade Lake and above, or any exposed open slopes or meadows below.
- My in/out times were about 9 moving hrs up/6 moving hrs down. If the snowpack firms up I'm sure you can shave an hour or two off that.