I have been raising chickens in the cold up here for the past 15 years, I am used to it. Kudos to all of you down there that had to improvise in the past week to keep your flock healthy. You are good guardians.
I install a tarp every fall and remove it in spring, chickens get used to the flapping sound after a few days, don't worry. The thing that they don't get used to is if a feet or so of snow accumulate on the roof of the run that all of the sudden break off and fall on the sides, they freak out, chickens get in coop for rest of the day.