Originally Posted by JayPowHound
Trails are often closed because they cannot SUSTAIN skier traffic throughout a day. For the first guy or five down them, however...
The other reason is that the whole trail might not have enough snow or there may be a more dangerous section that warrants caution for the masses. But those thin days that you are talking about, that's the day when you really need rock skis. Be careful, I mentioned Vertigo and there are plenty of others that can really mess you up.