Flooding in Arizona as Monsoon Brings Heavy Rainfall

U.S.|Monsoon rains wash cars off the road in Arizona, with warnings of more flash floods to come.

Monsoon season in the Southwestern United States is providing relief to parts of the region that are desperate for any kind of precipitation, but life-threatening flash floods and lightning are also part of the deal.

On Thursday night, a downpour in Phoenix and Scottsdale, Ariz., brought heavy rain, lightning and National Weather Service cellphone alerts of “a dangerous and life-threatening situation.” Cameras for the state’s Department of Transportation showed cars being washed off Interstate 17.

Like much of the West, Arizona, New Mexico and western Texas are battling a yearlong drought. Monsoon season generally starts in those places in June and runs through September.

Last year, though, the monsoon didn’t bring much rain. But this year has already seen a dramatic difference — a 200 percent increase in precipitation over the last two months in parts of the Southwest.

“Too much of anything is always a bad thing,” said Dave Lawrence, a National Weather Service meteorologist who covers the Western United States.

With heavy thunderstorms in the forecast through the weekend, flash flood watches were issued Thursday, lasting through Saturday, for central and eastern Arizona, as well as western New Mexico and southwest Colorado — where last week a torrent of water surged through parts of the Grand Canyon, leaving one camper dead.

“We’re most concerned about areas that have been burned by wildfires this year,” said Mark O’ Malley, a meteorologist for the National Weather Service’s branch in Phoenix. “Those areas will be particularly susceptible to flash flooding from the heavy rainfall.”

But despite the risks, meteorologists said the Southwest’s wet season still presents a welcome return to normalcy, particularly as the West battles a punishingly dry summer.

“The monsoon season looks more normal,” Mr. Lawrence said. “If there is such a thing as normal for weather — which there isn’t.”