Light showers do little to reduce Sonoma County rainfall deficit

The smidgen of rain falling from Sunday into Monday and another band of showers later in the week will have scant impact on Sonoma County’s rainfall deficit, and the long-range forecast calls for below normal precipitation statewide through April.

“It’s not looking super-favorable at this point,” Brooke Bingaman, a National Weather Service meteorologist, said Sunday.

The disappointingly dry trend, coming in what is usually the heart of the rain season, is “not a huge surprise,” she said.

With a La Niña weather pattern shunting most storms well north of the Bay Area, Santa Rosa had about 40% of normal rainfall Sunday — less than 10 inches since the Oct. 1 start of the rain year compared to an average of nearly 2 feet by this time of year.

Sunday’s showers are expected to diminish quickly by Monday afternoon, bringing about one-tenth of an inch of rain to Sonoma County’s valleys and up to three-tenths of an inch in the hills.

“Not anything to write home about,” Bingaman said.

A sunny, dry spell is expected to hold from Tuesday through Thursday morning, with Santa Rosa temperatures in the low- to mid-60s, she said.

Another weak front from late Thursday into Friday may bring less than a half-inch to the hills even smaller amounts in the valleys.

“At this point we’ll take any moisture we can get,” Bingaman said, “but is it going to push us back to normal? No.”

The weather service’s Climate Prediction Center expects below normal precipitation from February through March in all but the northernmost tier of the state.

The greater Bay Area has a 33% to 40% probability of below-normal precipitation for the three months and from Central to Southern California the chance of subpar rainfall ranges from 40% to 60%.

More than 99% of California was abnormally dry or at moderate to exceptional drought, according to last week’s U.S. Drought Monitor, with Sonoma County about evenly split between moderate and severe drought, the two lowest drought conditions.

California’s rainy season is starting about 27 days later now than it did in the 1960s, according to research reported by The Los Angeles Times.

Less rain is falling in the “shoulder seasons” of fall and spring — and more in the core winter months — leaving the state more exposed to catastrophic wildfires erupting in the fall, when vegetation is at peak dryness, the newspaper reported.

Eight out of California’s 10 most destructive wildfires, in terms of structures lost, have occurred from September through November, including the Tubbs fire in October 2017 and the Camp fire in Butte County in November 2018.

You can reach Staff Writer Guy Kovner at 707-521-5457 or guy.kovner@pressdemocrat.com. On Twitter @guykovner.