First of all, if this blizzard is really this bad, will the adults suggest moving somewhere else until it passes? If they don't, then why not? I don't mind them being trapped in the great valley, if that's what you're going for, but unless your planning for this to devolve into Donner-party style desperation and infighting, it'll be hard to work out dramatic plot elements if nothing can go in or out of the valley. What is this blizzard, anyway? Is it simply a freak of nature snow storm, a Plauge with a supernatural cause, or something ambiguous that could be interpreted as either (much like the bad luck of Saurus rock)?