The National Weather Service says a significant storm will bring between a quarter and a half-an-inch of rain to the valley and up to 2.5 inches of rain to the Sierra.
David Rowe with the weather service says there will be snow too.
"Probably about a foot to a foot and a half at the ski areas and maybe 2 to 3 inches down to about 4,500 feet," says Rowe.
Rowe says there are also flooding concerns in areas scarred by wildfire last summer -- for example the Rim Fire near Yosemite.
"When you get heavy rainfall intensity in a short amount of time, you tend to get mud and dust and debris left over from the fires last summer that'll accumulate and run downhill," he says.
Rowe says this will be a significant storm, but the region needs a series of these storms to start recovering from the drought. He says the forecast is dry again for the weekend and early next week.
Rowe urges valley commuters to use caution, especially Thursday morning, when the roads are likely to be slick, and says chains will likely be required in the Sierra.
The weather is about to change. Attached is the NOAA prediction for snow onI-80. Be prepared for winter driving. pic.twitter.com/kEvvfGXHAo— Caltrans District 3 (@D3PIO) January 28, 2014
There was "minor improvement" in California drought conditions over the past week. But as long-term drought persists throughout the west, and storage levels drop, water supply is a worry.
(AP) — The House has waded into a long-running California water war. Lawmakers have endorsed a Republican plan to shift more water to San Joaquin Valley farmers and cut the flow for threatened fish and growers in another part of the state.
The U.S. Drought Center says the past week brought "widespread improvements" in drought conditions in northern California and Nevada.
California's energy grid manager says supply should be adequate for the summer, despite potential natural gas shortages in Southern California.
California water regulators will allow cities and water agencies to set their own conservation targets based on water supply.