HIKING -- Utah canyoneers look to weather reports to help plan their entry into slots that can be death traps in sudden rain storms.  Sometimes the weather forecasts change.  That's an agency overseeing visitor safety to do?

After 7 die in flash flood, Utah national park evaluates permit system
A flash flood on Sept. 14 killed a party of seven who were canyoneering through Zion National Park's Keyhole Canyon, a narrow slot canyon that requires ropes and harnesses, and thus a permit from the Utah national park. The permit was issued at 7:30 a.m., when the weather forecast predicted a slight chance of rain, and thus a "moderate" chance for a flash flood, allowing the party to obtain a permit. The weather changed. People died. After the worst day in the park's history, the permitting system is under review.
--Salt Lake Tribune