Storms have hit areas of the Southwest again, but with less intensity than a day earlier when monsoon rains swamped the desert region, stranding drivers, flooding streets and prompting water rescues.

Forecasters warned of the potential of more flooding in six states -- Arizona, New Mexico, Colorado, Nevada, Utah and California, particularly in washes and streams.

Rain fell in the Four Corners region Wednesday but there were no reports of flooding or mudslides. More intense monsoon rain was expected in that area through Friday, according to the National Weather Service.

Flood watches in effect covered large swaths of desert and forests and cities such as Phoenix, Las Vegas, Tucson and Albuquerque.

There was some flooding in the Arizona border city of Nogales.

Meteorologist Ken Drozd said more than an inch of rain fell on the U.S. side of the border along with 2 inches on the Mexico side, overwhelming washes and some streets. Fire officials, however, said the water was receding by late afternoon and traffic was moving normally.

Heavy rains fell Wednesday in parts of northern Phoenix, according to report on the Arizona Republic website. And in Casa Grande, about 50 miles south of Phoenix, a monsoon storm knocked over trees and power poles. The Casa Grande Dispatch reported that up to 1,800 homes and businesses were without electricity for a few hours.

A flash-flood watch remained in effect until late Wednesday night for the Phoenix metro area and parts of Maricopa, Pinal and Gila counties -- meaning flooding was possible in washes, creeks and drainage areas.

Just over a month ago in Phoenix, residents were swapping social media photos of boiling temperature readings. Now, images of flooded streets and dark skies were being shared after a storm dropped 2 inches of rain in an hour in some spots Tuesday.

The rains bring some relief to crews fighting wildfires but also the potential for mudslides in areas blackened by flames. Because of the moisture, forest managers have been allowing wildfires to burn in areas where they didn't threaten structures or public safety.

While there are fears that lightning could spark new blazes and strong winds could fan them, flooding remained the main threat, according to the National Weather Service in Flagstaff.

The weather wreaked havoc on Tuesday evening's commute.

Flooding closed an Interstate 17 underpass in Phoenix for five hours and firefighters rescued a man sitting atop his flooded car on the metro Phoenix thoroughfare.

Arizona Department of Transportation spokesman Steve Elliott said pumps were overwhelmed by 3 inches of rain that fell within about a half-hour at an interchange where the freeway dips below street level.

"We're talking about moving swimming pools of water," Elliott said. "Those low-lying areas are great collectors of water."

Heavy rain is typical during monsoon season. The phenomenon occurs each summer when the winds shift, bringing moisture north from the Pacific Ocean and Gulf of Mexico to produce radical and unpredictable weather changes.

"So a normal monsoon year you're going to have a few of these extreme events. It may sound like an oxymoron -- they're extreme events but we know they're going to happen every year," Waters said.

At least one Phoenix couple took advantage of the weather for some wet and wild fun. Alexandria Gleason and Levi Robertson came home from work to find the streets around their apartment building flooded.

"Levi was the one who jokingly suggested I should get one of my floats," Gleason said. "I said `That's probably the best idea ever."'

Gleason said she bobbed in the streets in her doughnut-shaped float for about 15 minutes as the rain poured down.

Robert Goluba, who lives in the Phoenix suburb of Gilbert, captured video of a recycling bin floating down the street in front of his home. The 15-year Arizona resident said Tuesday's storm was one of the stronger ones in recent years and he'll be ready for the next storm.

"I'm going to be waiting for somebody's Mercedes to float down to my yard," Goluba joked.