While I can't always do that when camping in campgrounds, I:
1) Do hook up the truck; and set the parking brake. Lower landing gear or tongue jack to lock the trailer to the truck (DO NOT remove all the weight; just enough to make sure the trailer is supported.) Lower all stabs.
2) Avoid being directly under trees if possible.
3) Try to park next to a concrete or block building to block wind.
4) Retract slides but not if they block an exit.
5) KNOW where the tornado shelter is for the campground.
ASK if they don't tell you.
6) Buy, and keep "on", a dedicated weather radio with alarm.
GO to the shelter when it goes off. NO QUESTIONS
Lou and Laura with Bella - German Short Hair Pointer
2008 GMC Sierra 2500HD Crewcab SB Allison Duramax
2010 Flagstaff 8526RLWS - Superglide 3300
HAM CALLSIGN - KC3FFW