Southwest Storms Threaten Flash Flooding Across Four States

Millions of residents across the southwestern United States face renewed flooding threats as powerful storm systems move into the region from Saturday evening through Monday. The National Weather Service has issued flood watches covering nearly all of Arizona and portions of Nevada, Utah, Colorado and New Mexico after weeks of unusually heavy rainfall left the ground saturated.

Forecasters warn that additional rainfall could trigger dangerous flash floods, rising rivers and flooding along smaller waterways. The National Weather Service estimates that some areas could receive up to 4 inches of rain, while forecasts for the Phoenix-to-Flagstaff corridor indicate totals could reach 5 inches through Monday, according to Fox Weather.

The Four Corners region, where Arizona, Colorado, New Mexico and Utah meet, faces particularly serious conditions. Fox Weather reported that a Level 3 out of 4 flash flood risk covers more than 65,000 square miles and affects over 4 million people.

The National Weather Service's Weather Prediction Center described the incoming system as a significant rainfall threat.

Officials characterized the system as "a high-impact heavy rainfall event."

Recent storms have already produced deadly flooding across the Southwest. Two people died in New Mexico during flooding the previous week, while rivers in several areas reached their highest levels in 50 to 100 years, according to Fox Weather.

In Henderson, Nevada, emergency crews conducted three swift-water rescues during Friday afternoon's heavy rainfall. A person rescued from a drainage channel later suffered cardiac arrest and died at a hospital, according to a city spokesperson cited by ABC News.

Arizona also experienced significant flooding. The Phoenix Fire Department reported rescuing people from four vehicles stranded on flooded streets Friday night. In nearby Scottsdale, firefighters rescued three people after two vehicles entered the same flooded roadway.

Scottsdale Fire Captain Dave Folio warned that even relatively shallow water can create serious dangers for motorists.

"Just 2 inches of water can sweep your vehicle off its wheels," Folio said in a video posted on Facebook. The vehicles involved in the rescue operations were reportedly surrounded by 3 to 4 feet of water.

Allison Santorelli, a meteorologist with the Weather Prediction Center in College Park, Maryland, explained why additional rainfall presents an immediate threat to communities already affected by repeated storms.

"It's not going to take much rainfall to be impactful at all in some of these locations just because of how saturated they are," Santorelli said.

In western Arizona, heavy rainfall also left water, rocks and debris across streets in Bullhead City, prompting officials to close several parks, according to city announcements.

The National Weather Service office in Pueblo, Colorado, urged residents to complete preparations before conditions deteriorate.

"Folks, the window for flood preparations is closing," the office warned.

Higher elevations in Colorado face an additional winter weather threat. The San Juan Mountains could receive between 12 and 18 inches of snow as colder air moves into the region Sunday night, according to Fox Weather.

The National Weather Service warned that snowfall could create dangerous driving conditions across southwestern mountain roads.

"This will likely cause travel impacts along the southwestern mountain roadways, with dangerous and slick road conditions, especially Sunday night into Monday morning," the agency said.

Beyond the Southwest, the storm system is expected to move across the Plains and Midwest beginning Monday. Nearly 40 million Americans face a Level 1 out of 4 flash flood risk extending from Texas to Wisconsin, according to Fox Weather.

The FOX Forecast Center said atmospheric conditions could support additional severe thunderstorms as warm, moisture-rich air meets an approaching cold front.

"Right now, a limiting factor is how much instability or storm energy will set up in the region," the FOX Forecast Center said.

The forecasting team also noted that conditions were becoming increasingly favorable for stronger storms.

"Still, the atmosphere is becoming primed and energized for severe storms to develop from Texas into parts of the Southeast," the center said.

The broader storm system is forecast to continue eastward later in the week, potentially bringing additional heavy rainfall to major cities along the Interstate 95 corridor on Thursday and Friday.