Late April is getting a little dicey depending on what we get snow wise and how quickly it warms up. The past two years have been dismal. So you may be facing "spring snow" conditions. Us Coloradans are begging, hoping, praying, and wishing for massive March and April snowfalls to start filling up the rivers. Colorado is an arid climate, which I'm used to, but this drought is starting to get to me. The poor trees and grass are browning and looking so thirsty, the bears aren't cubbing much, etc. Anyway ...
There are two excellent nordic centers in the area: Breckenridge and Frisco. Check out their Web site at
http://colorado.net/~nord/. They're usually pretty good about updating which trails are open, snow conditions, etc.
You can also easily drive up higher from Breckenridge (the town itself sits at only about 9000? feet) towards Leadville, Vail, etc. in pursuit of snow.
Of course, a great alternative is to enjoy some spring hiking. It's always beautiful there in Summit County.