FRISCO —Summer may announce itself with crashing thunder, but winter usually arrives quietly, with the whisper of falling snow. You have to listen very carefully to hear it. The best place is in a hushed aspen glade, or a thick stand of evergreens, where the flakes brush against the boughs as they sift out of the sky. Since we’re dependent on snow in so many ways here in Colorado, it seems appropriate to spend a few minutes in reflective thanks when it arrives, time I always consider well spent. Here’s to lots more of it this year.