My Garmin 305 - a GPS gadget for people who love numbers and also love running, hiking, & bicycling. An hour into snowshoeing up Brown Mountain and several miles from the start the Garmin 305 says Ive been hiking about a minute and have gone 190 feet. That was walking across the road. Generally it works great but here you can see that it barely functions in a snowy forest of large trees, even in a clearing. I think the tree snow blocks the satellite because it generally works in this same forest in Summer.
When I arrived home and synced it with my Macbook it did create a reasonable map of my trip, however, so it must have been finding satellites here and there.
By the way, it doesn't look like it but it was very warm that day - record high temperatures (50 degrees F).