Just like other 'dangerous or risky activities or sports', the danger is always part of that risk assessment. You know what to expect and so long as you have developed the skill and some strategies to assess and deal with those risks, chances of being caught out are greatly reduced. Every case that is thrown at you however is its own case - one rule will not solve all situations. The objective is to never panic and to remain calm and be well prepared and comfortable with your own skills. It is imperitive with anyone that chases to work as a team and not to be panic striken. It is simply too dangerous to have someone that loses the plot as it can not only endanger ones life, but of those of the team. It just introduces another complexity to the situation.
The most significant risks in storm chasing are lightning and hydoplaning. When encountering the core of a severe storm, risks increase of flooded roads, reduced visibility and also trees and debris being hurled onto the vehicle. Having windscreens or windows shattered are also risks storm chasers need to consider. Tornadoes can and do pick up and hurl vehicles - let alone get pierced by debris!