California will see widespread rain and heavy Sierra Nevada snowfall through midweek, potentially bringing travel problems and raising the risk of damaging runoff from wildfire burn scars, forecasters said Tuesday.
The wet pattern from a deep atmospheric fetch of Pacific moisture marks a significant change in the weather following conditions that contributed to disastrous and deadly wildfires up and down California, where hundreds of thousands of acres have burned this year.
"This is good news to help minimize that fire activity," Cal Fire spokesman Scott McLean said . "But remember that if you are in an area that has seen recent fires this year or latter part of last year it could mean trouble as that soil is much more prone to mudslides and debris flow."
The National Weather Service said there was a risk of heavy rainfall in northwest California through Tuesday night, then spreading farther south down virtually all of the coastal ranges and some interior sections of the state through Wednesday and Thursday.
Snow accumulations in the Sierra could range from 2-4 feet (0.6-1.2 meters), the NWS said.
In the Sierra, chain controls were put into effect on Interstate 80 between Kingvale and the Donner Lake interchange, the California Department of Transportation said.
On the coast near Big Sur, Caltrans planned to close a section of Highway 1 between Mud Creek and Paul's Slide for 48 hours starting Wednesday morning because of potential instability.
The scenic route perched between towering mountainsides and the ocean has been dogged by slides since late 2016. But the one that hit Mud Creek near Ragged Point in May 2017 was monumental. Millions of tons of earth moved, displacing 75 acres (30 hectares) of land and extensive work was required to rebuild the highway over the slide.
Caltrans also warned that chains will be required for travel through the mountains of San Bernardino and Riverside counties east of Los Angeles when the storm arrives there Wednesday evening. Flash flood watches were to go into effect Thursday morning in those area as well as parts of Orange County.
Forecasters also warned of very high surf along the coast.