I hear you knocking. I can see why that is a worry. To be honest, I think that later on this evening and overnight, the volume of showers going into Wales along with strong Nw'erly winds, will drive showers inland. The Welsh hills will probably zap some of them but because of the strength of the wind, they should survive.Edit: When I said that some areas should do well, I meant from snow showers rather than any substantial depths.
I wouldn't rule out 3-5cm in some areas, but on the whole, 1-2cm dusting looks more likely.
Still, better than nothing hey?