Three hours delay may be unrealistic to some parents, and advantageous to others who can't leave their children alone at home. Ultimately, I think the parents should be informed as early as possible and be allowed to decide for their children, in situations where the teachers themselves were able to get to school, otherwise, it's pointless to get the kids in there isn't it.
While on the children's perspective, snow days are awesome! And getting a false joy was just the worst. You hear the name of your school on the radio, and 2 hours later, you hear that turns out they want you to come in.... Forget it, the parents better hear that message because I don't see a kid not lying is way out of that one : I didn't hear the second message pa! I swear!
(Northern Quebec represent, you think you had snow days bro, I've had to crawl out of my third floor window to get groceries when I was a kid. I remember going to school in a snow bus, oh yes, a SNOW bus ^^ Even seen telephone poles bloody buried, although only once.)