Although I think most afternoon ceremonies will be over before the real risk starts, my article from three weeks ago concerning prom may be relevant for event planners/managers this afternoon:
Steps to Prepare for a Tornado Outbreak
How to Prepare for a Tornado Outbreak was written with a larger outbreak in mind than today, but you may find some of the points in it relevant today, especially in the moderate risk area:
We hear it over and over again, yet we see it every single time there’s a storm! Severe Weather Awareness: Here’s Why Not To Park Under a Bridge in a Storm
How Storms’ Biggest Killer Does Its Dirty Deed
Bottom line for today: be wary, not worried. Be ready, not complacent. Act, don’t react.