The fact is, mother nature has her own rules. I'm past 65 and have seen many emergencies over the years and have watched the news of many deaths. Things like The Big Thompson flood here in Colorado took out many a camper as have many sudden water downpours throughout the world. I've been in Phoenix motels and have been swimming in the pool and suddenly everyone runs to their rooms where we watch from the window as the rain water reaches over the curb in a half hour.
Desert and mountain water storm water paths, washes in this case, can suddenly become roads not to be driven down. Quickly, suddenly. So yeah, usually one has enough time to get out of the way but 1000 vehicles getting out 2 exits that start filling with water is ok for the first few hundred but. Now, no one is expecting the odds of that happening.
I've been in desert sand storms where one had to pull over because you couldn't see. A lot of people there walking back to their cars on a road that the videos said both RVs and people should not be on at the same time.
So while I don't think there is going to be an emergency I am not stupid enough to say it absolutely cannot happen. I've been in 70 mph Santa Ana winds and had my shed end up next door. Those poor people in California had fire with their wind. So I think the people camped a bit further out are the smarter cause they will get out ahead of the biggest traffic.
I was in a tent once and the desert wind came down so hard it almost suffocated us because the material came down over us. My porta potty lid flew off and I found it half a desert away (not really but it was far and caught in a bush).
Now, the previous videos touted numbers of 5,000 showing up. So far I see far, far less so the traffic is far, far less than expected and being handled quite well.