Monsoon rain in the Southwest is putting a dent in the extreme to exceptional drought across the region, and portions of Arizona and New Mexico are seeing some of the most significant improvements.
Over the next couple of days, the monsoon rain threat will diminish across those states, the National Weather Service said, and focus instead on southern portions of California, Nevada and Utah.
Rain was reported Monday morning in the Los Angeles area.
Although the rainfall helps diminish the drought, it can lead to dangerous floods.
"The heavy rain will create mainly localized areas of flash flooding, with urban areas, roads, and small streams the most vulnerable through Tuesday morning," the weather service said. In the San Diego area, the weather service warned that "life-threatening debris flows will be possible near recent burn scars."
Over the weekend, a flash flood swept away a 16-year-old girl in Cottonwood, Arizona. The girl, Faith Moore, who had been trying to cross a flooded road in her car, was missing as of Sunday evening.
"I want to stress again to the public how dangerous these water crossings can be, even when it looks shallow," Verde Valley fire district chief Danny Johnson said. "A simple decision to cross the road with running water can quickly turn tragic."
The body of a 4-year-old girl swept away by floodwaters in southeastern Arizona last Thursday was discovered Monday.
And three flood fatalities in Albuquerque, New Mexico, last week mark the deadliest flooding event at least in recent memory in Albuquerque, said Lt. Tom Ruiz, a spokesman for Albuquerque Fire Rescue.
Although there was a slight chance for thunderstorms over Northern California and into Oregon, including where some of the nation's worst wildfires are raging, the threat of lightning strikes and gusty, erratic winds was not good news for firefighters battling the blazes there, the weather service in Sacramento said.
In Arizona, nearly 99% of the state is in some form of drought, according to the most recent U.S. Drought Monitor, which is published each Thursday.
The extent of the drought improved across the Southwest over the past week because of the rain, according to CNN. "The highest level of drought fell from 58% to 36% and marked improvements are expected again this week, with this current burst of monsoon moisture," the network said.
Though the rain itself is popularly called a "monsoon," the term scientifically means a seasonal shift in wind direction. In July, winds shift from the usual dry, westerly direction to the south and southeast, which taps into moisture from northern Mexico.
It's that moisture that contributes to the summer thunderstorms that cause flash flooding. Even a small amount of rain can cause flooding, because it can't soak into the rock-hard, bone-dry ground. Still, the monsoon provides more than half the annual rainfall to many communities in the Southwest.
The word "monsoon" is derived from the Arabic mausim, meaning "season," according to the American Meteorological Society. Monsoon season usually runs from July until September in the Southwest.
The Southwest monsoon is not nearly as intense as the Asian monsoon, which often brings catastrophic flooding to India and other nations.
Contributing: Elinor Aspegren, USA TODAY; Chelsea Curtis, The Arizona Republic; The Associated Press.
This article originally appeared on USA TODAY: Southwest monsoon brings drought relief but also flooding