LOS ANGELES, CA —Much of the Southland woke to monsoon rainstorms Monday, causing flash flooding in the recent burn scar areas, the National Weather Service reported. Power outages were reported across Los Angeles County and Orange County, where nearly 1,600 residents awoke without power. Commuter traffic was at a crawl as residents navigated area freeways in the pouring rain.
Scattered showers would persist on and off throughout the day—heavy at times— though the monsoonal moisture was expected to clear the region by Tuesday morning.
Meanwhile, a flash flood watch was in effect for parts of Los Angeles County stretching through Monday evening, the National Weather Service said. It would remain in place across Los Angeles County\'s mountains and burn scar areas until at least 8 p.m. Monday, according to the National Weather Service.
The flash flood watch affected the L.A. County Mountains, excluding the Santa Monica Range; the San Gabriel Valley; and the Antelope Valley.\' The NWS said areas likely to be impacted included Lancaster, El Monte, East Los Angeles, Topatopa Peak, Reyes Peak, West Covina, Alhambra, Falling Springs, Pasadena, Pomona, Palmdale and Whittier.
The culprit of the flooding: a monsoonal system that entered the region from the east, leading to scattered showers and thunderstorms — some capable of producing heavy downpours, with rainfall rates up to an inch per hour —are possible, the NWS said.
Locations most susceptible to flash flooding include those in and below recent burn areas, including the Bobcat, Dam, Ranch2, and Lake burn areas. Shallow mud and debris flows capable of producing localized damage are possible in and below these burn areas, the weather service said.
A flash flood watch means that conditions may develop that lead to flash flooding. The NWS advised residents of affected areas to remain alert and follow the directions of emergency preparedness officials.
Residents can find more information from the USGS on debris flows and their impacts at landslides.usgs.gov.
Much of Los Angeles and Orange County experienced power outages as heavy storm cells moved through the area Monday morning. The largest—a 1,600 home power outage affected much of inland Orange County in the Yorba Linda area for several hours.
The outage was reported just after 4 a.m. near a Southern California Edison facility at Fairmont Boulevard and Avenida Rio Del Oro, according to Orange County sheriff\'s Lt. J. Montano.
The outage was related to an Edison facility at that location, he said. He was not certain whether power lines were downed in an early morning rainstorm or a transformer fire. Edison reports that by 7:15 a.m., SCE workers restored power to those affected by the outage. Check for SCE outages in your area.
By Tuesday, the storm system would be clear of the area, leaving sunny skies and patchy low morning clouds and fog across the region.
As the system blows through so will increased wind speeds, with sustained breezes from 10 to 15 miles per hour Tuesday afternoon. The humidity would remain, with as much as 60 to 70 percent along the coastline and 40 to 60 percent humidity inland.