I spoiler coded this early, maybe in the other thread, but here's my take on Jonathon's death.
It seemed pointless and over nothing. Jonathon goes back to the truck to save the dog. Which, I'm sorry, you're pretty much bred to simply not do in Kansas when it comes to going to safety from a tornado. You're told to get yourself and family to safety and to not worry about pets if you can't get to them. Going back to the car to save the dog was an idiotic move in the circumstances they were under. All of the humans were "safe" (an underpass, really, isn't all that safe place to be when covering from a tornado) Jonathon should've gotten to safety too and not worried about the damn dog. And I say this as a dog lover. Jonathon also, pretty much, "decides to die.'
Here's what I would have done:
Have a human trapped in a car or possibly a child cowering in a car than Jonathon and Clark go back to save/convince to come with them. They manage to save him/her and are running back for the underpass, along the way a gust of wind or debris from the tornado comes down and pins Jonathon by the leg. Clark stops and looks back and Jonathon says, "Go! I'll be right behind you!" Clark hesitates but continues on as Jonathon tries to free his trapped leg.
Clark makes it back to the underpass and hands the child off to his mom/the parent and looks to his dad whose still struggling to free himself, we see that the tornado is almost right on top of him. Clark looks as if he's going to speed in and do his thing but his father looks up to him and shakes his head just as the sweeping winds carry away Jonathon and the car.
THAT would've have meant something and seemed more like a dire situation rather than Jonathon standing there, having saved a dog, and just going. "Meh, don't save me."