A parched strip in central California is expected to receive welcome rounds of rain and snow over the next week, but the forecast raises concerns about flash flooding and landslides in areas that have suffered a fire season treacherous forest last year.
Starting Friday, weather systems will bring a mixture of rain and snow to parts of northern and central California through the middle of next week, with much of the snow expected in the high elevations of the Sierra Nevada. Between 5 and 10 inches of precipitation is expected, although some areas could receive as much as 15 inches over the next two weeks, said Greg Carbin, chief forecasting operations manager at the National Weather Service’s Weather Forecast Center. .
“These areas have been unusually dry,” Carbin said. “In fact, much of California has had much below normal precipitation and rainfall for many months which led to the dramatic wildfire activity that we have also seen.
A cluster of fires known as the LNU Lightning Complex spread across Napa County and surrounding areas starting in August, burning more than 360,000 acres. It was 100% contained in early October, but the charred ground it left behind is more sensitive to rainfall runoff, according to the National Weather Service.
“If you have too much rain in an area where vegetation has been burnt due to forest fires, it can cause a problem with debris flow, mudslides and flash floods,” Carbin said.
Mountainous and hilly terrain could be vulnerable to flash floods and landslides, especially where there are scars from burns – charred and barren areas scorched by forest fires. In 2018, at least 17 people died in landslides in Montecito, southern California, after a storm hit hills that had been stripped of vegetation from the Thomas Fire.
The weather systems affecting central California are not out of the ordinary, as the state receives the majority of its precipitation during the colder months, particularly the January through March period. But the forecast is remarkable for an area where precipitation and snowfall “have so far been below normal” in recent years, Carbin said. (According to the National Drought Mitigation Center, parts of central California and the Sierra Nevada region are currently experiencing extreme and severe drought.)
California’s 2020 ‘Year of Water’ – the 12-month period that ended September 30, 2020 – has been rather dry for the upstate region, the Department of Water Resources reported. of State.
The Sierra Nevada can receive between about 70 inches of precipitation and over 100 inches per year, Mr. Carbin said. According to the Western Regional Climate Center, the north central and north coast regions of the state received more than 50 inches of precipitation in 2017.