I remember working on houses during some good storms. It tends to get too bad outside - for thunderstorms, the power tools dont get used and everyone takes shelter inside. But there was no plan ever.
I guess in regards to sever weather with tornadoes - the big stuff, it hasn't happened on any job that I worked on that we did something. I'm sure our instinct would have kicked in to take shelter if it was going to hit us, or if it was in the distance - watch the darn thing.
as far as the cold cold weather - where pulling wire sometimes isn't the greatest thing to do, well sometimes I have pulled wire in the cold. But if the job is mostly outside and not much inside work to do, the job is postponed. Also - if the roads are terrible to travel on, some days we didn't work. (snow/ice).
With MN the weather can change within an hour, so basicaly we adapt to most anything.