A large swath of the southwest U.S. encompassing about 10 million people is under flood watch due to a potential tropical cyclone, CNN reported.
“The stage is set for southern Arizona and New Mexico to potentially receive prolific rainfall and widespread flash flooding today,” wrote the National Weather Service (NWS) Weather Prediction Center (WPC) on Saturday.
The WPC has instated a “moderate risk” warning for excessive rainfall in southeast Arizona and southwest and central New Mexico, as well as a “slight risk” warning in western Arizona, the Texas panhandle and the Four Corners and Rockies region.
“Urban locations in addition to areas of complex terrain, slot canyons, arroyos, and burn scars are especially vulnerable for flash flooding and can quickly turn into very dangerous situations,” the center warned.
The WPC said that the precipitation is associated with a “remnant tropical wave” during an “ongoing active monsoon season.”
In addition, the center said that a potential tropical cyclone could reach southern Texas as a tropical storm on Sunday.
“This system is adding uncertainty and complexity to the forecast across Texas for the next couple of days. Areas of heavy rain and some squalls are expected to move into southern Texas on Sunday as the system arrives,” it wrote.
Storms have already upset some areas, including Zion National Park, where a person went missing on Friday.
“Following a search and rescue operation that began on Friday, August 19, the Narrows and Riverside Walk will remain closed,” the official Twitter account for Zion National Park wrote on Saturday morning. “The Zion Search and Rescue Team will continue to search for a missing person on Saturday, August 20.”