State surveyors who measured California's paltry Sierra Nevada snowpack on Tuesday might have fared better had they waited another day.

A winter storm carrying the prospect of up to five feet of snow for the Northern Sierra was expected to hit late Tuesday night and last through Wednesday, putting state road crews on alert while brightening the state's water outlook heading into spring.

"After tonight, you probably don't want to travel in the Sierra until Thursday," said George Cline, a forecaster with the National Weather Service.

State surveyors from the Department of Water Resources measured the Sierra snowpack on Tuesday and found it just 30 percent of normal.

The Northern California storm could ease fears among the 29 agencies that depend on snowmelt delivered through the State Water Project that already are bracing for meager allocations. Some farmers on the west side of the San Joaquin Valley have been told to expect just half of the water they requested for the spring and summer growing seasons.

The forecast calls for snow in both the Sierra and Coast mountain ranges with the biggest wallop coming above 6,500 feet, where accumulation could be between two and four feet, and up to five feet at the highest elevations.

The cold front sweeping down from the Gulf of Alaska will also bring gusts up to 110 mph along the Sierra crests, and 60 to 70 mph "where people are," Cline said. Snow levels could drop to 2,000 feet.

"It's going to be pretty miserable through tomorrow," he said.

Caltrans is bracing for what could be the biggest snowfall of the extremely dry winter by having Sierra crews work continuously on 12-hour shifts. On Interstate-80, the main east-west trucking corridor in Northern California, at least 200 people operating 134 pieces of equipment will be on duty. On Interstate 50, 100 people and 74 pieces of equipment will be working to keep roads clear.

Supervisors on the road will monitor ice conditions and decide with the California Highway Patrol when to require chains.

In the Coast ranges, forecasters predict six to 12 inches of snow above 3,000 feet and four inches at 2,000 feet. Up to a half-inch of rain is expected in the Sacramento Valley with scattered showers farther south.

Along the coast, up to an inch of rain could fall on areas north of the San Francisco Bay, with showers diminishing near Monterey.