By Matt Weiser
The flood warning, issued by the National Weather Service, lasts through 3:15 p.m. Friday and covers virtually all of the state's interior from Woodland north. A warning means that flooding is imminent or has already been reported.
Rainfall amounts of 2 to 3 inches over the Sacramento Valley and 4 to 8 inches over the mountains are expected during the period of the flood warning. Rapid rises in small streams and possible flooding along them is anticipated in some locations, especially on streams feeding the upper Sacramento River in the area of Red Bluff.
"It's going to be the smaller creeks, the foothill streams not regulated by dams, where you're going to have your problems," said Maury Roos, chief hydrologist at the California Department of Water Resources, which activated its statewide flood operations center on Wednesday. "I would say that's the more likely threat."
Rain began about 3 p.m. Thursday in Sacramento and is expected to become heavy after midnight. Winds also picked up and may gust to 55 mph in the Sacramento Valley and Sierra foothills and reach 70 mph at higher elevations.
Residents are encouraged to help keep street gutters and storm drains clear of fallen leaves, avoid driving through standing water, and prepare for power outages.
Flood bypasses on the Sacramento River are expected to begin filling as soon as Friday in Colusa County as the river swells, relieving flood pressure on urban levees. Downstream, water is predicted to begin spilling into the Yolo Bypass, between Sacramento and Davis, on Sunday evening.
CalFire and U.S. Forest Service officials are keeping a close watch on areas burned by summer forest fires, including the Chips Fire in Plumas County and the Ponderosa Fire in Shasta and Tehama counties.
"We're pulling all non-essential personnel out of those areas that might be at risk from mudslides and debris slides," said Stanton Florea, a Forest Service spokesman. "We have small engineering teams of two to three people that are ready to go out and do rapid assessments after a mudslide."
One of the more unusual developments is a threat of flooding in downtown Reno from the Truckee River as the warm storm pours rain on the Sierra Nevada. The river is expected to briefly exceed flood stage in Reno on Sunday afternoon, possibly flooding riverfront parks and other low-lying areas near the river.
PHOTO: A man and woman walk along a vista point looking toward the Golden Gate Bridge and San Francisco from the Marin Headlands this afternoon. The National Weather Service says that by late morning Thursday 1 inch of rain had fallen in several hours across the western side of the county. Much of Northern California is under a variety of warnings and advisories for rain, snow and high winds. Jeff Chiu/Associated Press