Atmospheric river triggers evacuation and flash flood warnings in North Bay

The North Bay is bracing for the worst as heavy wind and rain, brought on by a winter storm, sweep through the area Tuesday evening. 

The National Weather Service upgraded a flash flood watch to a warning as the atmospheric river arrived. The warning includes Sonoma County and is valid until 11 p.m. Tuesday. 

Along with the rain and high wind advisory is the possibility of mudslides, which has county officials on alert and asking residents to be prepared.

"Transportation and public works have been preparing for this event since right after the fire season. The scar burn areas have been stabilized as best as we can so we don’t expect any major sides however we’re monitoring all the area," said Johannes Hoevertsz, Director of Sonoma County’s Transportation & Public Works Department.

The potential for mudslides is greatest in the areas affected by the Meyers, Walbridge, and Glass fires last summer.

Ahead of the storm, five fire engines, staffed with 20 additional firefighters will be on standby in Santa Rosa to offer assistance, particularly in the fire burn scar areas said Chief Mark Heine with the Sonoma County Fire District.

With the rain forecast to stick around for several days, residents are preparing their homes by picking up sandbags offered by Sonoma County in Cotati.

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"You have to be sure to protect the area where it floods and the water rises," said Jose Montalvan. "Several years ago, it rained so much that my whole yard filled with water and I brought some gravel to fill in the low spots, but still it doesn’t help, but the sandbags do help."

On the Russian River near Forestville, a big operation is underway to deflate the inflatable dam that supplies water to the area.

The water agency routinely deflates the rubber dam when the Russian River flow forecasts show the river reaching 2,000 cubic feet per second.

During what meteorologists call an atmospheric river, the flow is forecast to reach about 5,000 cubic feet per second.

"It would damage the bladder itself so that’s the reason that we lower it because the high flow could cause it to be damaged," said Barry Dugan with the Sonoma Co. Water Agency. "When the water gets too high likes it’s going to in this storm, we have to lower it "

Paul Lowenthal, the Assistant Fire Marshal for the Santa Rosa Fire Department said that he expects crews will be responding to a lot of trees and power lines down with winds coming out of the south.

Residents should call 9-1-1 if you see a downed power line.

If you still need sandbags to defend against flooding, you can stop by 55 Stony Point Road in Santa Rosa. You should bring identification to show you live in the county.

Napa County issued an evacuation warning Tuesday evening for residents living in burn areas considered at higher risk of flash flooding, mud, and debris flows during an extended period of heavy rain predicted for the reason. 

The warning for the period overnight from Tuesday to Wednesday is based on an updated briefing from the National Weather Service, officials said. 

The flash flood watch by the NWS extends from 4 p.m. Tuesday to 4 p.m. Thursday for the LNU Lightning Complex and Glass Fire burn scar areas, with the heaviest rain predicted for Tuesday night to 10 p.m. Wednesday. 

"This evacuation warning is to advise residents within fire-impacted areas to remain alert to possible threats and to consider safety plans in the event of a life-threatening emergency. There is no immediate need to evacuate," officials said. 

The NWS advised that "rainfall thresholds may trigger the issuance Flash Flood Warnings overnight and residents in impacted areas may receive (emergency) alerts on Tuesday night into Wednesday morning." 

Residents near the two burn scars should prepare for potential debris flows, landslides, and flooding, officials said, advising, "If you feel the need to leave, now is an opportunity to do so safely." 

There is also a high wind warning issued for midnight to noon on Wednesday. 

"Strong and damaging winds could cause downed trees and tree limbs, possibly impeding evacuation routes" and causing power outages, officials said, advising residents to keep cell phones charged and monitor local radio stations for information.

Bay City News contributed to this story