Strong storm brings heavy rain, flooding to Sonoma County

An atmospheric river dumped rain Thursday across the North Coast in the most significant storm of the season, flooding roadways, toppling trees, causing power failures and causing vehicle spin-outs and strandings.

The National Weather Service issued a flash flood warning for southeastern Sonoma County and northern Marin County until 5:15 p.m. as creek gauges rose above flood stage, particularly in Petaluma, Agua Caliente, Rohnert Park, Sebastopol and areas around the Laguna de Santa Rosa. Low-lying roadways also flooded.

The heavy rainfall and wind lasted much of the day before dissipating as the fast-moving storm continued on its southward course.

Friday morning, things should be back to a semblance of normal, with perhaps some drizzle before things dry out.

The forecast for the coming week calls for mostly dry weather but freezing morning temperatures are expected over the weekend and into Monday in the North Bay.

The California Highway Patrol said the storm flooded over 30 roads in Sonoma County and there were about 15 crashes in a five-hour period Thursday morning, but none with serious injuries.

The rain did, however, brighten the region's water picture and improve prospects of ending a stubborn drought.

There were three main power failures, according to PG&E spokeswoman Deanna Contreras. The first, at Sea Ranch, began just after 7:30 a.m., affecting 290 customers. Power was restored about 2:15 p.m.

In Rohnert Park, 327 customers lost power just after 2 p.m. By 9 p.m., three customers were still without power. And in Cazadero, where 282 customers lost power when a downed tree hit electric lines, 66 remained without power late Thursday night, with service not expected to be restored until early Friday morning.

Santa Rosa registered 2.86 inches of rain over a 24-hour period ending at 4 p.m., bringing the season total to 17.6 inches, almost twice the normal average for the date. Venado, a small community in the hills west of Healdsburg and a perennial wet spot, logged 7.16 inches total over the past two days, the most of any weather station in the Bay Area.

Roads flooded across Sonoma County, from Dutcher Creek Road in Cloverdale to near Kelly Road, as well as the area of Hall and Willowside roads in west Santa Rosa and Mark West Station Road at Starr Road.

In Mendocino County, low-lying roads that tend to flood were closed, including Highway 1 at the Garcia River, Highway 128 near Highway 1 and Highway 175 east of Hopland.

Other roads were closed by downed power lines, including Redwood Drive between Guerneville and Monte Rio. Between Sebastopol and Occidental, a fallen tree shut down Freestone Flat Road.

Other roads affected by downed trees or power lines included Fort Ross Road, Cazadero Highway and Calistoga Road at Alpine Road.

Some motorists tried to navigate inundated country roads and got stuck, prompting rescues by emergency responders.

“The biggest issue is people trying to cross flooded roads,” said CHP Officer Jon Sloat, who said they end up mired in high waters requiring a fire department response.

“It's really a waste of resources for something so preventable,” he said.

The CHP also stressed the need for drivers to slow down in the rain, citing speed as a factor for spin-outs and crashes on Highway 101.

While the rain is ending, the National Weather Service was predicting morning lows in Santa Rosa of 28 degrees Saturday, dipping to 27 Sunday and rebounding only slightly to 31 Monday morning.

Brad Sherwood, spokesman for the Sonoma County Water Agency, said both Lake Sonoma and Lake Mendocino - sources of water for more than 600,000 North Bay customers - were around 90 percent of capacity before the storm hit.

Sherwood said the latest deluge builds on a strong start for the water year that began with the second wettest October on record.

While Thursday's storm overflowed small creeks, it was projected to bring the Russian River only to several feet below flood stage.

“It's picture perfect the way these storms are rolling in,” he said, producing a lot of rain without severe flooding followed by a dry spell allowing rivers and streams to subside.

“We were dreaming of a wet winter and it looks like that's coming true,” Sherwood said.

You can reach Staff Writer Julie Johnson at 707-521-5220 or julie.johnson@pressdemocrat.com. On Twitter @jjpressdem. Staff Writer Clark Mason can be reached at 707-521-5214 or clark.mason@pressdemocrat.com.