The National Weather Service has issued a rare advisory telling Central Valley residents to turn off their lawn sprinklers today through at least Saturday to conserve water as a storm is expected to drop up to 0.25 inches of rain.

The advisory comes as a moderate storm system that is looking more like the real thing and not another dud moves into the Northern San Joaquin Valley early Thursday morning and lingers into the weekend. It has an 80 percent chance of materializing. Most of the rainfall will occur Thursday and Friday with lingering shows primarily in the Sierra over the weekend. The chance of rain is 20 percent on Friday.

The advisory is a nod to the severity of the fourth straight year of drought. And while the rainfall won’t ease the drought, the moisture it brings will allow people to conserve water by turning off landscape irrigation systems.

The Weather Service calls for two to four inches of snow above 5,500 feet along Highway 50 and Interstate 80 with primarily rains and thunderstorms possible in and around Yosemite Valley.

Some 1.25 inches of rain could fall on the western slope and the foothills.

There is a chance for travel delays in the mountains do to wind and snow with chain requirements a possibility.