Everyone is dead. What we see are their ghosts.
Take for instance, young!Jo, we see her dad get sucked out of the cellar, and shortly thereafter it quickly cuts away. Jo actually died in there. Nobody else in the movie dies, except for Jonas and his driver, But we Never Found the Body. Nobody not directly connected to the main characters ever interacts with them. It also explains why Jo and Bill don't die at the end. They're all in Storm Chaser Valhalla, they can't die twice.- Jonas and his driver didn't just die. They were vaporized in an explosion.
Bill is related to Gerry and Sarah Harding.
Being good at science runs in the family, but unfortunately, so does ending up in dangerous situations.His instinct for predicting what the storm will do just by sniffing the dirt and looking at the sky is more reliable than a whole caravan of instruments, and his wife calls him a "human barometer". He may have a low-level mutant power of special sensitivity to the weather, plus some enhanced durability to explain driving through the explosion and surviving the ending. Alternatively, he may have unconscious Weather Manipulation abilities, creating tornadoes just as he arrives in the area and starts to think about storm chasing again, which become stronger as his romantic struggle to choose between Jo and Melissa becomes more serious, and ultimately kill the rival he hates, but never harm him or anyone traveling with him. The stakes were literally sky-high.
If Jonas' team had successfully deployed their package first, their sponsors would have an indefinite patent on the resultant advanced warning system, essentially making tornado country into a corporate fief; work for them or get left out of the evacuations to preserve corporate property("We paid for the system, we have the right to use it as we see fit to protect our property and employees." {piss us off and it all gets deleted neener neener neener}) - this was probably Jonas' pitch that got him 20 vans full of equipment and personnel. Since Jo's team got the data(and Jonas bit the dust), the warning system will become a NOAA resource, just like the weather service. It really is a supernatural/Sci-fi movie
Bills almost psychic ability to predict storms and tornadoes, is the biggest point, but also the behaviour of the Tornadoes themselves, they make noises that people generally agree isn't how a tornado sounds, but also the waterspouts merging together and happening to catch Bill, Jo and Melissa, one tornado suddenly vanishing and then reappearing while Bill and Jo are in the open, another huge one happening to come by as the group are in a relatively open and insecure movie theatre, and the final one dramatically altering it's course to come after Bill and Jo, The actual plot is that The Tornadoes aren't after Jo, they are after Bill because he can predict them and succeeds in countering them using Dorothy, they don't like it.- Not really. Tornadoes can act erratically, changing direction or speed without warning. The movie is quite realistic.
The Watsonian explanation for the apparent weird tornado behavior is people being terrified and panicky
- When Jo was a little girl, she witnessed her father being blown away in a storm and his death has haunted her ever since. She almost has to believe that tornados are malevolent entities with a grudge against her and/or her family specifically rather an a random, senseless accident in order to cope with her grief.
- And then when you're trying to outdrive a huge-ass tornado, it may not really act like a Super-Persistent Predator but good luck convincing your fight-or-flight response otherwise.
The Tornado that killed Jo's father wasn't an F5.
As mentioned in Anachronism Stew, there were no F5 tornadoes 1969, it was simply that Jo was a child at the time, and the trauma caused her to massively overinflate how powerful the tornado actually was, so when the Fujita scale was introduced, she insisted that the tornado was an F5, because, like most kids, she believed only something so powerful as an F5, could take her father from her.