1 dead, 15 potentially missing after ‘significant flash flood' at Grand Canyon

( Yahoo )

One person has died and approximately 15 people remain missing or unaccounted for after a flash flood ripped through Grand Canyon National Park's Bright Angel Canyon on Saturday.

All hotels in the park will also close starting Monday for overnight guests after the flooding damaged a key water supply pipeline through the park; no reopening time has been given.

Strong thunderstorms dropped about two-thirds of an inch of rain in 15 minutes atop recently burned areas around 2:30 p.m. Saturday, sending a slurry of mud and debris rushing through the canyon. Floodwaters rose more than 5 feet in 10 minutes and destroyed bridges across Bright Angel Creek and forced the closure of one of the park's most difficult trails.

A flash flood watch remained in effect in the Grand Canyon through Monday as forecasters warned of dangerous downpours in Arizona and Utah.

The body of a 46-year-old man was found near Crystal Rapids along the Colorado River, National Park Service officials said Sunday night. No other information about the death was immediately available, but a medical examiner was onsite.

The park initially said that more than 20 people could be missing or unaccounted for, but it appeared to revise the number down to around 15 Sunday afternoon.

In addition, 62 campers and hikers were airlifted out of the area.

Daniel Evans, 43, hiked alone to Bright Angel Campground, which was hit by some of the most intense flooding, Saturday morning. Nothing seemed out of the ordinary at that point for the experienced outdoorsman, as he sat in his tent and read. But by early afternoon, drizzling rain turned into a downpour, and hail began to batter his tent. Water levels rose rapidly and within minutes his campsite was flooded.

Park rangers then walked over to Evans and other campers and told them they had to evacuate.

At that point, Evans said he and a group of about 40 people clung to the wall of the canyon beneath an overhang due to the risk of rockslides, while they waited to be evacuated.

They stood there for several hours, before a park ranger approached Evans and asked him how much he weighed. That's when it dawned on him that the group would likely be airlifted. Evans was among the first people to get into the helicopter. He was able to drive back home to Flagstaff in time for dinner.

"The flooding popped up out of nowhere and it was worse than anyone could have expected," he said. "I left there, like, 'sh--, we dodged a bullet.' I left in high spirits, but it was really disheartening to then find out that people were missing."

Evans said he was grateful he made it out uninjured and with his belongings. He saw other hikers who lost their phones, wallets and shoes, as he and the rest of the group shivered while they waited for the rescue.

As it works to locate unaccounted for hikers, the park service asked people staying in the inner canyon along the Bright Angel Creek corridor on Saturday and others with reservations there to touch base with the park's investigative branch.

"This includes individuals who may have been traveling along the North Kaibab Trail from the North Kaibab Trailhead to Phantom Ranch, staying at Bright Angel Campground, or traveling or staying in the area known as 'the Box' north of Phantom Ranch.

"If you know of anyone who may have been hiking or backpacking in these areas, please contact the NPS Investigative Services Branch Tip Line: 888-653-0009," the park service said.

Park officials closed Phantom Ranch, Bright Angel campground, the Phantom Ranch canteen and cabins along with the North Kaibab Trail. The Colorado River was shut down to traffic after metal structures and other debris entered the waterway. The Black Bridge and Silver Bridge crossing the Colorado River was also closed.

Staff warned they may need to make additional inner canyon closures as the chance of additional thunderstorms and heavy rainfall Sunday and Monday threatened to unleash more flash flooding, park officials said.

Cell phone service throughout much of Northern Arizona is difficult to maintain, the park service warned, adding to the challenge of finding the missing.

"It is nearly impossible to get and keep a signal at Grand Canyon, Marble Canyon, Arizona Strip, and area tribal lands," it said. "Satellite phones are being tested with some success in places outside of the narrowest portions of the canyon."

Sensors along the Bright Angel Creek indicate water rose feet in just minutes, but streamflow data was likely erroneous due to flood damage, according to the U.S. Geological Survey.

Saturday's flood occurred a year after the Dragon Bravo Fire ripped through the Grand Canyon's North Rim and destroyed a historic lodge.

Bursts of heavy rain on recently burned landscapes can trigger debris flows, a slurry mix of mud, trees and rocks. A moderate to high-severity fire can alter the physical and chemical makeup of the soil and may make it completely repellent to water.

A park service assessment of the Dragon Bravo burn scar last summer found that "debris flow risk is localized to steep, confined drainages, like Dragon Creek and upper Bright Angel Creek."

Short-duration rain bursts, such as thunderstorm downpours, are more likely to trigger debris flows than long-duration moderate rainfall.

A weather station along Bright Angel Creek measured 1.17 inches of rain between 2 and 3 p.m. Saturday, which far exceeded the National Weather Service's flash flood guidance for the Grand Canyon. That prompted the agency to issue a flash flood warning.

A slight (level 2 of 4) risk of flash flooding remained across Arizona on Sunday and Monday. A flood watch - indicating favorable conditions for flooding - was in effect for a majority of the state through Monday. A flash flood warning - indicating an imminent or occurring flood - was issued just before noon along the Colorado River in northern Arizona, upstream of Grand Canyon National Park.

The weather service said overall coverage of downpours Sunday "should be a bit less" than Saturday, but flooding was more likely in areas that are hit by heavy rainfall multiple hours or days in a row due to "saturated grounds."

A moderate (level 3 of 4) risk of flash flooding was warned in south-central Utah on Monday. That included many recently burned areas in the state, which experienced an extreme burst of fire activity in June.