Having had it happen where it just slides down literally as one big lump and TOTALLY removes your vision, I mean literally the same as shutting your eyes, I really do think its EASILY more dangerous than doing 85mph on a motorway, so if thats going to have 3 points then the snow certainly should!

Needs to be applied fairly though, its only if you have a couple of inch block of snow on your roof that its an issue, but no doubt some arsehole coppers will start handing the points out for someone with just a few specs of snow