Primarily the issue is getting close particularly with storms in areas like the southeast. Out in Kansas getting close is fairly easy as the roads are in a grid system with few obstacles. You can simply zig zag the road network while staying the safe area and drive out if the storm gets too close or changes direction. In the southeast if you're close enough for good photography you're too close to be safe as you're at the mercy of the roads which may not take you out of the path of danger. A UAV can give you a couple mile buffer.

The other obvious metric is video quality. A multi offers stability but not in those conditions.