re: A map of every tornado emergency ever issued

Another thing to think about:

Imagine a day like April 27, 2011, or any day where there is a threat for long-track violent tornadoes. Take one of the EF5 tornadoes in Alabama that day. It was on the ground for 132 miles, from near Hamilton, AL to near Huntland, TN.

Now, look at a map of Alabama and the cities/towns potentially in or near the path of that thing, and what vital infrastructure was in those towns (Nuclear plants, chemical plants, major rail hub on the river, multiple industrial parks along the river, etc). 132 miles of Alabama/Tennessee ground was covered. Overlay that 132 mile path onto the Plains states. Go to West Texas or Western Oklahoma. You can have a violent tornado on the ground for 100+ miles out there and it may never get near an area with any significant population.