cross training

I have been running great all summer long 35-50 miles a week. I will be training for a 21 mile race in May, but that means I have to run hard during the winter when I usually cut back. My concern is that I go back to work in a week, and the days get shorter. What are peoples experience with cross training such as cross country skiing or snowshoeing? I ride and swim right now, but as extras not substatutions for running. Will my running be hurt if I run less, but cross train more? I do not go to gyms! Thanks in advance.

In Arizona, we don't do much snow shoeing:D but I can tell you that cross training is important. Especially if you're running, you need to give your knees, hips, hamstrings, etc. a break.
It won't hurt your running. If your race is in May, you'll have time to get your running legs back. Any chance you could use a treadmill during the bad winter months?