Wettest October in 3 years in Sonoma Valley

More than 10,000 Sonoma County residents had power outages as a result of a “atmospheric river” that soaked the North Bay this weekend.|

An uncommonly strong storm led to Sonoma Valley’s wettest October in at least three years, according to the National Weather Service.

Sonoma Valley saw around 4 to 5 inches of rain in most areas as part of an “atmospheric river rain” event that is uncommon for this time of year, said Brayden Murdock, a meteorologist at the Bay Area National Weather Service. Some parts of the county saw as much as 14 inches of rain, with flooding and road closures reported all over the region. The wet weather doused flood-prone Schellville, filling cars that mistakenly tried to pass through the water-logged roadways at Highway 121 and Highway 12.

At least six vehicles -- including a Porsche, a Mercedes-Benz and a BMW -- were water-logged as the drivers attempted to pass through flood waters, according to California Highway Patrol Napa office.

All of the drivers were able to safely and successfully exit their vehicles without need for a rescue, CHP Sgt. Brad Bradshaw said.

This is the first “atmospheric river” event since January, Murdock said. “As far as the last two atmospheric rivers of the calendar year, this one was the big one.”

The rain brings much needed water to drought-stricken California, although much of the water is flowing out through rivers and tributaries, said Steven Lee, senior scientist and research program manager at the Sonoma Ecology Center.

“Having that kind of volume happen slowly in an area like ours where it can percolate into the ground can have significant positive impacts on the ground water level,” Lee said. “But when it comes all at once, the way it did, most of this just runs off into the creeks.”

Creeks that had ran dry for much of the past year were flushed with rain water, such as those in Agua Caliente, according to the U.S. Geological Survey. But there was little absorption into the ground to refill ground water levels, Lee said.

“This was a significant volume of rain that came down, it’s just that it comes all at once,” Lee said. “Adobe soils don’t allow for much percolation. When you have rain like that coming across adobe soils, it’s more likely to run straight to the creek.”

Lake Sonoma is collecting water from the Russian River watershed, Lee said. However, the water levels in the lake were “significantly far down” and much more rain will be needed to get the region out of drought conditions.

Yet the vegetation and local wildlife will reap the benefits of the downpour, and local residents can expect a “greening of the hills” in the coming weeks, Lee said.

More rain is expected into the winter months when weather events like the one seen last weekend are more common in the forecast.

“It is a little bit uncommon to have atmospheric rivers in October,” Murdock said. “It's not completely unheard of, but usually we see our atmospheric rivers more in the winter months December, January and February.”

The storm also knocked out power to more than 10,000 individuals in Sonoma County and more than 18,000 in the North Bay counties, PG&E reported.

“There are approximately 3,000 electric and tree crews on the job,” PG&E announced in a press release Sunday. “Hundreds more employees are staffing the storm centers, performing safety duties, delivering needed equipment to PG&E yards and more.”

Cal Fire also published a press release Sunday, lifting the suspension on burns by Tuesday at 8 a.m. in Sonoma, Napa and Lake counties. The decision was made as a result of precipitation and a drop in temperatures.

The public will again be allowed to burn with Cal Fire permits and local air quality permits because the threat of fire is low at the moment, according to a Cal Fire spokesperson.

While there is no official word on the end of fire season, the lift of the suspension on burns is an indicator that the end of the season may be approaching, Murdock said.

“We'll have to wait for those measurements of individual fuels to say anything specific about if we're done worrying about fire conditions,” Murdock said.

Kaylee Torres contributed to this report.

Contact Chase Hunter at chase.hunter@sonomanews.com and follow @Chase_HunterB on Twitter.

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