The risk of localized flash flooding continues through the end of the week over part of the interior West.
Cities at risk for flash flooding during the random storms include Las Vegas, Phoenix, Tucson, Flagstaff, Albuquerque, Salt Lake City, Cedar City in Utah and Riverside, Calif.
According to Western Weather Expert Ken Clark, "An upper-level disturbance drifting in from the Pacific will focus an already in place flow of tropical moisture, known locally as the monsoon."
The end result will be more numerous and locally, extra-drenching showers and thunderstorms from interior California to New Mexico, northward to Utah and Colorado.
The storms will tend to favor, but not be limited to the high ground.
Isolated downpours can quickly flow downhill, causing canyons and arroyos to quickly fill with water.
The spotty downpours can also lead to debris flows in recent burn areas.
While area residents will welcome any non-destructive rainfall, a number of the storms will bring little or no rainfall, frequent lightning strikes and the risk for new wildfires.
"By the end of the week the storms will consolidate farther to the east and south over the Four Corners states as drier air invades from the north and west and the disturbance pushes inland," Clark added.
At such time the risk for flash flooding in Las Vegas and Phoenix will have ended.
Meanwhile, a stalled front will continue to bring rounds of drenching thunderstorms and the risk of flash and urban flooding to parts of the southeastern U.S. this week.
A storm system responsible for severe weather across the Plains over the past week, as well as the snow across the Rockies will advance eastward.
The Highway Fire started around 6:10 p.m. PDT Saturday near Corona, California, in the Prado Dam area in Riverside County, and grew from 30 to 175 acres in a matter of three hours.
For the second half of the weekend and into the week, rain and wind will replace the pleasant, sunny conditions of the first part of the weekend.
After a steady rain closes out the weekend, more showers and cooler air will persist through much of the week.
A pattern favoring waves of progressively cooler air will set up across much of the Midwest and Northeast during next week and could continue into early May.
Round after round of drenching rain will continue to cause flooding in the South, while another dose of rain may renew flooding in the Ohio Valley this weekend.
Central Europe (1991)
Cold outbreak: 12" of snow in the Swiss Alps; temperature dropped to 26 degrees in Berlin.
Lexington, MA (1775)
Lexington-Concord Day; crisp anticyclone morning at 0700: 45.7 degrees, 29 56" rising, wind west, force 1, "very fair" sky - Prof. Winthrop noted at Cambridge, MA: "Battle of Concord will put a stop to observing."
Southern New Hampshire (1785)
Last snow of a famous late winter raised snow cover to 3 feet. Crust that supported horses that morning began to dissolve that afternoon.