The new warnings carry added urgency after destructive flooding struck the Grand Canyon over the weekend. One hiker was confirmed dead, while authorities were attempting to determine the whereabouts of at least 15 other people reportedly unaccounted for.
Conditions across the region could make additional flooding especially dangerous.
A deep supply of tropical moisture has moved into the Southwest at the same time that slow-moving thunderstorms are expected to repeatedly develop. Making matters worse, portions of the region have already received significant rainfall, leaving some areas less capable of absorbing another deluge.
Southern Arizona could see another 1 to 3 inches of rainfall. Particularly intense thunderstorms may unload more than an inch in only an hour.
In the desert Southwest, that amount of water arriving in such a short period can quickly become deadly.
Normally bone-dry washes can transform into torrents. Narrow slot canyons can fill rapidly, sometimes giving hikers and tourists little opportunity to escape.
Meteorologist Max Velocity warned that the weather pattern could cause thunderstorms to repeatedly pass over the same locations, dramatically increasing the risk of flash flooding.
‘Dual upper-level disturbances lifting out of Mexico and California are fueling strong atmospheric lift across the Desert Southwest. Anomalous tropical moisture pooling across the region will fuel widespread thunderstorm development.
‘With wind shear organizing storms to repeatedly track over the exact same areas, rainfall rates could easily surpass one inch per hour. Sensitive features like slot canyons, dry washes, and recent-burn scars face life-threatening flash flood danger!’
Arizona is at the center of the threat.
The Tohono O’odham Nation, including Sells, was placed under a flood watch through Monday evening, with forecasters warning that storms could bring another 1 to 3 inches of rain.
Warnings also extended through northern and central portions of the state, encompassing Flagstaff, Sedona, Prescott, Payson, the Mogollon Rim, the White Mountains, and the Grand Canyon.
The situation at the Grand Canyon is particularly concerning following the weekend’s deadly flooding.
According to the National Park Service, rescuers recovered the body of a 46-year-old man near Crystal Rapids along the Colorado River. Authorities had not publicly identified him as the Coconino County Medical Examiner’s Office continued its investigation.
Officials were also working to account for people who may have been hiking or camping around Bright Angel Canyon and Phantom Ranch.
Authorities specifically sought information concerning anyone traveling along the North Kaibab Trail between the trailhead and Phantom Ranch. That search also includes visitors who may have stayed at Bright Angel Campground or passed through the narrow section north of Phantom Ranch known as “the Box.”
The flood reportedly sent an enormous amount of debris into the Colorado River.
Sediment, trees, bridges, and structures swept out of Bright Angel Creek reportedly created a blockage in the river, effectively raising its height by roughly eight feet.
Meanwhile, the Phoenix metropolitan area is confronting its own flooding threat.
Phoenix, Scottsdale, Mesa, Chandler, Glendale, Apache Junction, Casa Grande, and Globe were among the communities covered by watches.
Forecasters warned that repeated thunderstorms could drop another 1 to 2 inches in some locations, potentially overwhelming drainage areas and creating dangerous runoff.
Flood concerns also reached Buckeye, Avondale, Tonopah, Gila Bend, portions of La Paz County, and Sonoran Desert National Monument.
Farther north, the Northwest Plateau—including Tuweep, Colorado City, and the western Grand Canyon—could experience enough rainfall to push streams beyond their banks and make roads impassable.
And the threat does not stop at Arizona’s borders.
Utah’s world-famous national parks are also preparing for potentially hazardous conditions.
Flood watches included Zion, Bryce Canyon, and Capitol Reef national parks, along with Glen Canyon, Lake Powell, Castle Country, and the Sanpete and Sevier valleys.
Southeastern Utah was also included in the danger zone, affecting Moab, Arches National Park, Canyonlands National Park, Blanding, Bluff, and Monticello.
Western Colorado faces similar concerns.
Grand Junction, Aspen, Vail, Montrose, Gunnison, Telluride, Ouray, and Cortez could receive multiple rounds of heavy rainfall.
Another flood watch was issued for southwestern Colorado’s Animas and San Juan river basins, covering communities including Durango, Bayfield, Ignacio, and Pagosa Springs.
Officials are particularly concerned about areas recently damaged by wildfires.
Burned terrain can repel or poorly absorb heavy rainfall, allowing water, mud, rocks, and other debris to race downhill with alarming speed. Even rainfall that might otherwise be manageable can become dangerous when it falls over a fresh burn scar.
Urban drainage systems, low-water crossings, creeks, rivers, desert washes, and narrow canyons are all vulnerable as the monsoon pattern intensifies.
The National Weather Service is urging residents and millions of tourists across the affected region to keep a close eye on official warnings and be ready to move quickly.
Anyone planning to hike through a slot canyon or dry wash—or participate in activities such as boating and paddleboarding—has been advised to reconsider those plans as storms develop.
With saturated terrain, repeated thunderstorms, and exceptionally moisture-rich air converging over the Southwest, forecasters are warning that conditions can deteriorate rapidly.
For those in the path of the storms, a quiet desert wash or scenic canyon could become dangerous in a matter of minutes.
