Here's the timing of when rain, snow will roll in (February 28-March 2, 2018)
The biggest storm of the season began rolling into Northern California late Wednesday, kicking off four straight days of wintry weather that will drench the Sacramento area and deliver as much as 7 feet of snow with whiteout conditions to the Sierra Nevada.
As a late afternoon drizzle descended on the Sacramento region, the National Weather Service forecast heavy rains, gusting winds and possibly another hailstorm in the area - but no significant flooding. The Sierra Nevada was in for a severe pounding, with foothill areas as low as 3,500 feet likely to get as much as 5 feet of snow by the time the storm front departs late Saturday - the heaviest snowfall in the foothills since 2011.
Courtney Obergfell, a weather service meteorologist, said the fiercest snow will arrive Thursday but conditions in the Sierra will be difficult throughout the duration of the storm. Higher elevations will see 7 feet of snow in some areas before it's over, and Obergfell urged motorists to forgo any trips to the mountains.
"This is going to impact a long stretch of highway and ... traffic is highly discouraged," said Obergfell in a conference call with reporters. She said the weather service is "just trying to encourage people to ... wait until Sunday if they can." The weather service issued a winter storm warning for the mountain regions until late Saturday night.
In Sonoma County, meanwhile, officials urged residents to be prepared for flooding and other problems left over from last October's wine country fires. In Southern California, evacuation warnings were issued for areas overcome by mudslides in January.
In short, California is finally getting a dose of normal winter weather after an abnormally dry season. The latest storm isn't unprecedented; it's just long overdue this year.
"These (storms) can happen during the winter typically," Obergfell said. "We haven't had a lot of these recently."
Along with Monday's rain and snow, the new storm is expected to put a dent in the drought-like conditions that have plagued California this winter. But it won't completely remedy the season's water shortfall.
The weather service said Sacramento could expect 2 to 3 inches of rain by Saturday. Because river levels are low and temperatures will stay cold, the region should avoid any significant flooding except in areas where drainage is poor and flooding is frequent.
Obergfell said parts of the valley could get thunderstorms and another bout of hail Thursday, repeating the freakish conditions from Monday that convinced many Sacramentans it snowed.
Caltrans officials were gearing up for chain controls and road closures.
“We’re going to have a fun couple of days here, my goodness, shades of last year,” said Liza Whitmore, a spokeswoman for Caltrans.
She said intermittent road closures were expected, beginning as early as Wednesday night, at Donner Summit on Interstate 80 and Echo Summit on Highway 50. Motorists in foothill communities such as Placerville, Grass Valley, Nevada City and Auburn will see extensive snow on major highways and local roads.
“If you are going anywhere in the mountains and foothills, expect chain controls,” Whitmore said.
Caltrans also warned of localized flooding on valley roads.
Tahoe ski resorts, which have relied heavily on artificial snow for much of the winter, greeted the arrival of the real thing. "3-4 feet of more snow in forecast thru Sunday," blared the headline on the Squaw Valley-Alpine Meadows website.
Getting to the ski areas could be extremely difficult, though. Even though there will be some breaks in the weather, notably Friday, the weather service said motorists can expect lengthy delays because of the long hours it will take to clear the roads.
Winds in the mountains will gust as high as 50 mph, which will bring more travel problems. "It's going to be a fluffier, whiter snow, and so we're expecting issues with blowing snow as well, and that can cause whiteout conditions at times," Obergfell said.
Fluffier snow brings another downside: less relief for California's water supply.
Michelle Mead, the weather service's warning coordination meteorologist, said temperatures are expected to be so cold that the snow won't deliver as much water as usual.
"It's a drier snowfall, for sure, but we're going to take it," Mead said. "It's still a decent amount of liquid precipitation."
So far this year, rainfall totals in Sacramento and many other cities are about half what they should be for this time of year, and the Sierra snowpack - a critical source of water in summer and fall - is just 23 percent of average. The Department of Water Resources' closely watched rain-gauge index, which measures a mix of rain and snow in the northern Sacramento Valley, was at 57 percent of average heading into Wednesday.
The U.S. Drought Monitor, published by the federal government, said 91 percent of California was "abnormally dry" heading into this week, and 48 percent of the state was experiencing some degree of drought conditions.
Meanwhile, forecasters said Southern California could expect more than an inch of rain beginning Thursday. The Santa Barbara Sheriff's Office issued a recommended evacuation warning for areas of the county where mudslides killed more than 20 people and temporarily closed Highway 101 in January.
"High risk for loss of life and property exists," the Sheriff's Office said.