When it comes to the Sierra Nevada snowpack, a few weeks of rain can make all the difference.

After the first Philips Station snow survey of 2019 in early January revealed that Sierra water content was below average for that time of year, the Department of Water Resources most recent survey on Jan. 31 showed more promising results.

The manual survey recorded 50 inches of snow depth and a snow water equivalent of 18 inches, which was 98 percent of average for that location. Statewide, the Sierra snowpack was 100 percent of average at the time. By comparison, the Feb. 1. 2018 measurements at Phillips Station revealed a SWE of 2.6 inches, which was only 14 percent of the early-February average.

“The snowpack across California is on par with the historical average for this time of year, thanks in no small part to an atmospheric river that brought heavy snowstorms to the Sierra Nevada. Typically, California relies on a handful of large storms like we saw earlier this year.” DWR Director Karla Nemeth said. “It’s a start, but the next two or three months will determine what it means for our reservoirs and overall water supply.”

On average, the Sierra snowpack supplies about 30 percent of California’s water needs as it melts in the spring and early summer to meet water demands in the summer and fall.

“The data we collect allows us to forecast how much snowmelt will run off into our streams and reservoirs,” John Paasch, Chief of DWR’s Hydrology and Flood Office, said. “Snowpack is an important factor in determining how DWR manages California’s water resources each year to sustainably meet demands.”

Since early last week, a series of storm systems that moved through California added to those substantial snowpack numbers. As of Feb. 5, the state’s average SWE was 23.5 inches, or 125 percent of normal for the date.

The storm brought snowy conditions to Calaveras and Tuolumne counties throughout the weekend, bringing what officials say are the lowest foothill snow levels in years. The winter blast brought an estimated four to seven inches of snow down to 1,500-foot elevations, including Sonora, Columbia and other foothill towns by Tuesday.

Normally mild cities in Northern California, like San Francisco, also experienced a dusting of snow, with the peaks overlooking the Bay Area receiving a light powder —the city’s first notable snow in eight years.

At Yosemite National Park, all roads have been closed. The park’s ski area was shuttered, restaurants had shorter hours and shuttles were not running because of snow-covered roads.

“It's beautiful and we certainly need the snow, but we're asking people to stay indoors,” park spokesman Scott Gediman said. "As the weather improves, we'll plow roads and assess the situation.”

The Associated Press contributed to this story.