This year there's been a large-scale movement of these owls into the states and several have turned up in Pennsylvania. Unlike most owls, which are nocturnal, snowy owls are diurnal — they're active both day and night which makes them easy to see if one is in the area.
A Snowy was found recently near Shippensburg which isn't far from where I live so I went this afternoon to see it. It was a gorgeous bird, large and almost completely white. Younger owls have dark edges to their feathers giving a barred appearance, but older Snowies, especially older males, are almost completely white.
There's a very interesting story on this year's irruption of these birds which can be read here.