I went skiing in Shiga Heights Ski Resorts February 22. It was one week after big snowfall in Nagano, so the ski courses were covered with wonderful natural snow. We (five Japanese, one from America, and one from Britain) really enjoyed skiing and snowboarding in the best condition.
The big snowfall on Feb 8 and 15 are more than 2 ft even downtown in Matsumoto, which I have never experienced.
In the next day after the snowfall, beautiful blue sky and the Japan Alps were seen.
Ski season of this winter in many ski resorts in Nagano will be over in late March, but you can ski and snowboard until early May in some of the resorts in high altitude.