I don't know, I'm in southern NC now and never had chickens up in Maryland. You may need to reenforce it better than I did.
We don't get snow every year, and when we do it's one light dusting that's gone in a couple hours.
We've been here for 5 years and only once have we had "real" snow-- it was a good 6" and the governor deemed it a state of emergency and shut down EVERYTHING!
No school, no daycare, no grocery stores, no military installations for a WEEK-- it was pretty insane!
Granted they don't have any salt trucks or snow plows down here, but I grew up in Maryland it's got to be a blizzard to shut things down.
I have to admit I do get a chuckle when what we consider a minimal amount of snow can close down everything in a southern state. Though I also have to knowledge that I am a tad bit jealous when I think of a winter with little to no snow and relatively warm temps. I have learned to survive here, but am I ever happy when Spring comes (which isn't until May).