The State Climate Office of North Carolina posted a blog entry this morning describing two big cold air outbreaks that affected the Southeast in the past. They point out that temperature drops of 30 F or more can occur as cold fronts pass through the region, bringing damaging freezes and wintry precipitation to the area.
You can read about them at https://climate.ncsu.edu/climateblog?id=173&h=5666e5c1.
