Negligence:

"Negligence" is not the same as "carelessness", because someone might be exercising as much care as they are capable of, yet still fall below the level of competence expected of them. It is the opposite of "diligence". It can be generally defined as conduct that is culpable because it falls short of what a reasonable person would do to protect another individual from foreseeable risks of harm. In the words of Lord Blackburn,

"those who go personally or bring property where they know that they or it may come into collision with the persons or property of others have by law a duty cast upon them to use reasonable care and skill to avoid such a collision."..."For a defendant to be held liable, it must be shown that the particular acts or omissions were the cause of the loss or damage sustained."..."A typical formula for evaluating negligence requires that a plaintiff prove the following four factors by a "preponderance of the evidence":

The defendant owed a duty to the plaintiff (or a duty to the general public, including the plaintiff);
The defendant violated that duty;
As a result of the defendant's violation of that duty, the plaintiff suffered injury; and
The injury was a reasonably foreseeable consequence of the defendant's action or inaction.
For example, a person driving a car has a general duty to conduct the car in a safe and responsible manner. If a driver runs through a red light, the driver violates that duty. As it is foreseeable that running a red light can result in a car crash, and that people are likely to be injured in such a collision, the driver will be liable in negligence for any injuries that in fact result to others in a collision resulting from the running of the red light."

Based on this, I don't think it matters a whole lot how well prepared you are. If you go into a high risk environment and something goes wrong, then based on how the courts define negligence, you would be liable, especially if you drag a group of kids with you into it. It's all well and good to bring plenty of gear with you up the hill, but if you or someone in the group gets hit by lightning or otherwise injured, expect to get hammered for it, especially if you knew in advance that the conditions would be adverse.