A heavy downpour has hit southern California, causing Los Angeles authorities to prepare for possible flooding and landslides, US media reported on Thursday.
The National Weather Service (NWS) is forecasting up to 15 centimetres of rainfall in some areas. Of particular concern are regions affected by recent wildfires, where the risk of mudslides is high. A flash flood warning has been issued for much of Los Angeles County, with the greatest risk remaining near burned areas in Altadena and Pacific Palisades.
Landslides are possible due to loss of vegetation and hardening of the soil caused by the fires. Authorities are advising residents living near the hillsides to be prepared to evacuate. The storm is caused by an “atmospheric river” bringing significant moisture from the Pacific Ocean.
Hillsides charred during the outbreak of wildfires in September – the Bridge, Line and Airport fires – could threaten parts of Los Angeles, San Bernardino and Orange counties. Short bursts of heavy rain are enough to trigger dangerous landslides on steep slopes, dropping just a quarter of an inch in 15 minutes.
Heavy snowfall is expected in mountainous areas
The storm could bring more than four feet of snow to high elevations in the Sierra Nevada, with several inches down to the 2,000-foot mark. In Southern California, heavy snowfall is expected only at the highest elevations, above 8,000 feet.
The Northern Sierra, home to the state’s largest reservoirs, is doing well this year, with snow cover at 115 per cent of normal as of this date.
The Sierra Nevada is expected to get several feet of snow on Thursday and Friday. The Southern Sierra, however, is far behind, at just 53 percent of normal. Severe to extreme drought is blanketing the southern third of the state after the driest start to the rainy season on record.
While forecasters are still tweaking rainfall amounts, this week’s storm should bring at least some drought relief to the region and put an end to wildfire fears for an extended period of time.
