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.
Tropical Depression 8 should strengthen into a tropical storm before impacting the coastal Carolinas with rough surf and heavy downpours early this week.
Tropical Depression 9 developed just south of Florida on Sunday and will turn toward the northeastern Gulf Coast of the United States this week.
Brief relief from heat and humidity will arrive in the northeastern United States at the start of September.
Typhoon Lionrock is poised to make landfall in Japan near Sendai early this week with heavy rainfall, damaging winds and an inundating storm surge.
Two tropical systems, Madeline and Lester, could pose hazards to Hawaii from the middle of the week into Labor Day weekend.
Hot and dry weather will greet fans and competitors at the 2016 U.S. Open Tennis Championships in Flushing, New York, as play begins Monday, Aug. 29.
New England (1965)
A total of 2.5 inches of snow on top of Mt. Washington set an August record. Vermont had a reading of only 25 degrees, while Nantucket had a chilly 39 degrees. Earliest freeze on record at many stations.
Houston, TX (1980)
2.23 inches of rain fell in less than 1 hour. Streets were flooded in the downtown district and a tornado touched down briefly west of Houston at Sealy, TX.
Pittsburgh, PA (1982)
39 degrees, coldest ever in August.