This may not apply to where you are staying, but one lesson I learned when I was camped out near the southern entrance of Yellowstone close to the Teton's is apparently there is a weather event where a gust of wind comes down from the mountains, it only lasts a couple of minutes, but it's really pretty strong. It shredded my Inlaws awning (bent/broke the metal supports as well), and anything that wasn't secured got blown around pretty good. I'd never heard of this phenomenon before, but thought I would pass it along. If I recall, it happened around mid-day, and was a fairly common event in that particular location.