The second storm, forecasters say, could bring thunder and dump up to 2 inches of rain in central and southern valleys, 2 to 4 inches in the foothills and up to 6 inches in some mountain spots.
State water officials plan Thursday to survey the anemic mountain snow pack, and will likely find that California's precipitation is badly lagging what's needed to quench the region's thirst. 2013 was California's driest year on record.
In Nevada, the first of back-to-back storms dropped several inches of snow at Lake Tahoe and up to a foot and one-half on the mountain ridges.
A winter weather advisory was put into effect from 4 p.m. Wednesday to 10 a.m. Thursday for the Reno-Tahoe area, south to Mammoth Lakes.
The second wave of wetter weather begins Friday night into Saturday.
The National Weather Service has issued a severe thunderstorm warning for Sutter and Yuba counties until 1:30 p.m. Unsettled weather will continue through Saturday.
The storm that's been bringing strong winds, heavy rain and snow to much of Northern California over the past four days is weakening.
The California grape harvest dropped seven percent last year from 2014.
A winter storm is forecast to bring mostly rain in the Sierra Nevada Friday, with high snow levels. But Saturday, snow is expected at lower elevations.
The National Weather Service in Sacramento has issued an urban and small stream flood advisory for several counties in the region including: Sacramento, Yolo, Calaveras, Amador, San Joaquin and Stanislaus.