strong winds....leave it all hooked up and if possible drop the trailers stabilizers.
squall line 70-90 mph straight line winds....best to leave it hooked up and point the truck/trailer into the wind.
Tornados .....get out of both and get in a shelter.
There is no exact generic answer as every winds from storms will be different and may even blow from more than one direction. Too many variables such as are you on the road traveling or set up in a campground....and expected wind speeds.
Growing up in OK and camping in just a simple rain storm to overhead funnels ....90 mph straight line winds has shown me to be aware where your at in regards to storms path.