"Flash flood is a warning we give over and over again. A very quick storm can happen miles from where you are, and the sun is shining, and all of a sudden here comes this wall of water," said Larry Crutchfield, spokesman for the Grand Staircase-Escalante National Monument, said.

Sandstone does not absorb much water, and instead it drains into nearby canyons, sometimes by the bucketful, said Garfield County Sheriff's Deputy Ray Gardner.

"Slot canyons have their inherent hazards, but to me the reminder is: We need to be especially aware of weather," he said. "As far as I'm concerned, if there is even one cloud in the sky anywhere, I wouldn't go near a slot canyon, it's just too risky and dangerous."

When Kathy and Gordon Chapple entered a canyon known as Egypt Three with their family, some clouds were starting to form on the southwest horizon, Gardner said. But storms miles away can affect hikers in slot canyons.

Fast-moving thunderstorms passed above the Egypt trailhead area about 12:30 p.m. Wednesday, said Randy Graham, a meteorologist for the National Weather Service. The storms deposited 0.2 inch to 0.5 inch of rain.

The depth of a flash flood depends on the width of the canyon, and Egypt Three is only a few feet wide in some spots, Gardner said. Though only about three minutes elapsed between the start of the rain fall and the flash flood, the water may have been up to 20 feet deep, Gardner said.

lwhitehurst@sltrib.com

Staying safe

* Check the weather before entering slot canyons

* Sandstone absorbs little water, making flash floods more likely. Check the weather, and remember that storms miles away can cause flash floods in slot canyons.

* The narrower the canyon, the deeper the water.