FORT COLLINS, COLORADO — FORT COLLINS, Colo. (AP) — A region accustomed more to sweltering heat than wet weather is about to be submerged, raising the risk of flash floods that could surprise — and kill — in minutes.
It was downgraded from a strong hurricane, Tropical Storm Priscilla He has I lost my punch In the eastern Pacific Ocean near the coast of the Mexican Baja California Peninsula. But the storm is still carrying plenty of moisture and is now heading toward the southwestern United States, where flood warnings were posted Thursday.
Forecasters expect rain from Priscilla’s remnants to fall on areas of Arizona, Utah, New Mexico and Colorado this weekend, bringing as much moisture in hours as some of those places would get all year.
Recent deadly floods in Texas and New Mexico He talks about what can go wrong with rain this way.
“We don’t want to see people caught up in the risks that we’re going to see,” said meteorologist Robert Rickey of the National Weather Service in Flagstaff, Arizona.
Northern Arizona is most at risk, with 2 to 3 inches (5 to 8 cm) of rain possible in and around Flagstaff, the gateway to the national park south of the Grand Canyon.
Some areas could get more, but it’s impossible to predict where that will happen too far in advance, Rickey said.
The upland Flagstaff region gets up to 2 feet (60 cm) of rain annually, but not often in large doses. Southwest and northeastern Arizona see much less, in some places 5 inches (13 cm) or less annually; Phoenix gets only 7 or 8 inches (18 to 20 cm) per year.
In such deserts, heavy rains on paved urban landscapes with minimal sanitation infrastructure and in ravine-filled rural areas can quickly become deadly.
Anxious people headed abroad were calling the National Weather Service and asking if they should cancel. The agency remained open during the government shutdown.
“I had to have that kind of frank conversation with them,” Ricky said. “Is the risk worth the reward?”
After heat, floods are the deadliest weather phenomena in the United States, killing 145 people in 2024. Many of the victims were in their cars, braving rising waters that can be deceptively dangerous.
In Arizona, the “Stupid Motorist Law” allows drivers to be billed up to $2,000 if they drive around a barrier or warning sign in a flooded area and have to be bailed out.
By encouraging smarter driving, the law attempts to reduce the dozens of such rescues in the state each year. However, some worry that the law discourages people from seeking help immediately, putting them at worse risk. The law is not consistently enforced.
The desert and arroyo canyons of the Southwest are notorious for their risk of flash floods. Even storm miles (kilometers) upstream can turn a dry wash into a raging torrent, stirring debris downstream and blocking the trail for hikers and cars.
That’s what happened in southern Utah a few weeks ago, when a desert canyon flood trapped at least 10 people, all of whom were eventually identified by officials.
Mountains can also lead to deadly floods. In June, three people, including children between 7 and 4 years old, They killed In a flash flood at a riverside RV park.
Forested areas can be made worse for flash flooding if you recently burned vegetation that can hold back water and allow it to soak into the ground. This weekend, that includes the North Rim of the Grand Canyon, which burned in a massive fire last summer.
The National Weather Service posted a flood warning for most of Arizona, as well as southern Utah and smaller parts of California, Nevada and Colorado.
Powerful storms were already moving north through Arizona and southern Utah, dumping up to an inch (2.5 cm) of rain in some places. Scattered flash flood warnings were posted along the state line, including Lake Powell and Glen Canyon National Recreation Area.
Much of the rain in the Southwest during the summer monsoon season comes from sporadic storms from mid-June through September. Rainfall from tropical fall systems like this might happen once a year, said Ricky, the meteorologist.
In Flagstaff, heavy equipment was deployed throughout the city, and staff were monitoring low water crossings and areas where wildfires had burned for potential flooding.
Self-serve sandbags were available to residents in a city park, and water was released from the pond to make room for more runoff.
The Havasupai Tribe, whose reservation lies deep in a gorge off the Grand Canyon and is vulnerable to flooding, advised tourists in a social media post not to hike to certain areas if it is raining or flooding, and to seek higher ground if they see water flowing through the area.
The preserve is one of the most remote in the continental United States and can only be reached by mule or on foot. Tourists from all over the world visit the blue-green waterfalls and camp beside the creek.
Mike Rock of Junipine Resort in Sedona, which is located along Oak Creek, said staff were monitoring road and weather conditions and telling guests to take precautions.
Picnic tables near the creek will be moved in case of high water. He added that if flooding or falling rocks closes nearby roads, employees can stay at the resort, as is normal in bad weather.
He added: “All indications are that we will face great difficulty.”
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AP Assistant News Director Felicia Fonseca in Flagstaff, Arizona, contributed to this report.