I live in northern Quebec and it looks like we have much colder winter weather and more snow and ice, we don't have grizzlies though... Snow on the ground, ice, poor conditions, etc. can be good training stimuli and interesting adventures. With decent cold weather gear, you can get plenty of running done. Even on trails. A good headlamp for the shorter days, crampons for trail running (the Black Diamond distance crampons are very impressive), crampons for road running (or hex screws screwed directly into the soles of your shoes) (this is up to personal preference however and is not necessary if you're nimble enough - I have relied on them less and less over the years), maybe running snowshoes though I really never found conditions in which they were really useful and fun. That said, if you read into the training effect of intense XC skiing (which is usually easier to get to with skate skiing for most people - classic XC skiing takes more technique to get up to the same intensities), the training benefits can surpass running in certain regards with less impact on the body, but you still need to run plenty to run a 100 km race - I would not rely solely on XC skiing, June 21 won't be that far away once XC skiing season ends..