We will visit Wroclaw early December with kids, where is the nearest location which is likely to be snow and preferably reachable with train or direct bus?
Karkonosze Mountains - the highest peak, Śnieżka (Schneekoppe) did not get its name for nothing. However, December is only the beginning of winter and thanks to the effects of global warming it may be too early in the season for much snow. Check at short notice.
That's what I feared, Tom.