Heavy rains and flash flooding that washed away portions of the roadway prompted Nevada officials to close a nearly 50-mile stretch of Interstate 15, a major trucking artery that leads north from Las Vegas to Salt Lake City.
Nevada transportation officials said Tuesday the corridor could be closed for three to four days while they scramble to repair eroded pavement. They were diverting Utah- and Arizona-bound traffic to smaller roads, including U.S. 93.
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"I don't think it can be overstated just how important I-15 is to the three states," Utah Department of Transportation spokesman John Gleason said. "I would say the detours, in the best-case scenario, are not as convenient as I-15."
Seasonal monsoon moisture combined with the remnants of Tropical Storm Norbert to dump rain throughout the Southwest on Monday. Floodwaters submerged vehicles and homes in Nevada and Arizona and are blamed for at least two deaths in southern Arizona.
A woman died after her car was swept away and became trapped against a bridge in Tucson, and a 76-year-old woman drowned when her husband tried to drive across a flooded wash in Pinal County.
Phoenix recorded record rainfall for a single day, turning freeways into small lakes and sending rescuers scrambling to get drivers out of inundated cars. On Tuesday, many in the metro area focused on mop-up, while a flash-flood watch was issued for much of the rest of the state through the evening.
Parts of Nevada also saw downpours, and 190 people from an Indian reservation about 50 miles northeast of Las Vegas were evacuated after more than 4 inches of rain fell on the rural, sparsely populated community of Moapa, pushing the Virgin River to near-flood stage. Some homes were damaged.
Strong thunderstorms also wreaked havoc in Southern California's deserts. Rescue crews answered more than 40 flood-related calls about stranded cars during the Monday morning commute in the La Quinta and Indian Wells areas near Palm Springs, Riverside County fire spokeswoman Jody Hagemann said. Numerous cars got stuck in high water in Coachella Valley, said Mike Radford, spokesman for the Indio CHP office.
In suburban Phoenix, crews in Mesa were trying to keep floodwaters away from around 125 homes after retention basins and channels along the U.S. 60 freeway reached or exceeded capacity, allowing water to flow into a handful of neighborhoods.
Crews worked into the night to disconnect power to submerged transformers, provide sandbags to threatened homes, and pump water from affected areas. A temporary shelter was being set up at a recreation center.
Norbert's effects likely will hang around Tuesday, National Weather Service meteorologist Charlotte Dewey said. But she warned any additional precipitation could quickly cause new flooding because the ground is already saturated.
Sections of the two main north-south and east-west freeways through Phoenix — Interstates 10 and 17 — were closed during the Monday morning commute, snarling traffic all across the metro area.
Cars and SUVs sat in water up to their hoods on I-10 before the water receded and sunshine emerged. By late morning, trucks were able to take away several dozen vehicles that had been swamped.
The National Weather Service recorded 3.29 inches of rain at the Phoenix airport, by far the most precipitation the city has ever received in one day. The previous record was 2.91 inches in 1939.
Other Phoenix metro areas received staggering amounts of rain for the desert region. Chandler recorded 5.63 inches, while Mesa had 4.41 inches.
Monsoon storms from the Pacific Ocean and Gulf of Mexico can bring heavy rain and wind to Phoenix in the summer months. The last six years have produced a highly erratic pattern as Phoenix has gone from huge rainfall one summer to scant precipitation the next, said meteorologist Charlotte Dewey.
In Tucson, nearly 2 inches of rain in a short period turned normally dry washes into raging torrents. A woman was found dead after her car was swept about two blocks by water 10 to 15 feet deep then wedged and submerged against a bridge, Tucson Fire Department spokesman Barrett Baker said.
"This is the worst thing in the world for us," Baker said. "We talk all summer really about the dangers of washes."
In Tempe, part of a grocery store roof collapsed because of the rain, but none of the people inside was injured, police Lt. Mike Pooley said.
Arizona Gov. Jan Brewer declared a state of emergency because of the flooding and told nonessential state workers to stay home.
Scattered electricity outages were reported, with more than 10,000 customers losing power.
Associated Press writers Astrid Galvan in Tucson, Ariz., and Paul Davenport, Bob Christie and Alina Hartounian in Phoenix contributed to this report.