Atmospheric river to dump heavy rains on Santa Rosa, residents prepare

SANTA ROSA, Calif. - An atmospheric river storm is expected to arrive in the North Bay late Tuesday before spreading to the rest of the Bay Area later this week, likely bringing several inches of rain and wind gusts of up to 45-50 mph, according to the National Weather Service.

At Santa Rosa's corporation yard on Stony Point Road, folks were making sandbags not just for this week's storm, but for all the atmospheric rivers coming this fall and winter. 

"When it's normal rain, not a problem. When it starts getting really bad and they're expecting what, eight to twelve inches here in four days. So, we just want to make sure that everything stays dry," said Santa Rose resident Jonathan Taylor. 

Meteorologists have warned the next few days will be stormy in the Bay Area because both a bomb cyclone and an atmospheric river are developing in the Pacific. A bomb cyclone is how quickly a storm strengthens, while an atmospheric river is a steady stream of moisture racing across the Pacific. 

Northern parts of the Bay Area could see more than 10 inches of rain by the end of the week.  "At least for these first couple of days, the North Bay will really see the largest impacts from this system," national Weather Service Meteorologist Dial Hoang said.

By week's end, many parts of the region are expected to receive about a month's worth of rain. 

"When the ground is saturated, it starts to come toward the garage and the back door. Now it's never flooded the garage, but that's because I come out here doing this," said Cheryl Cole of Santa Rosa. 

Hoang said soil conditions in the Bay Area are somewhat dry because of the hot summer and this being the first big winter storm to hit the region, so that might mitigate flooding concerns somewhat.

"They might be able to soak up some of it initially, but it will saturate really quickly" and lead to flooding in some urban areas and along small streams and creeks, particularly in the North Bay, Hoang said.

"I'm expecting it to dump, said Pamela P., who said she wishes a Boy Scout Troop was here to help out.  "I can only do a half a bag. So, it would be more effective and less building if I could do the big bags. But we're gonna see; hopefully hope for the best here," she said.

The rains will fall on very thirsty ground. "Right now, soils are relatively dry, so they'll be able to saturate a lot of the initial rainfall, But, with the prolonged event that we're anticipating, we'll likely see a lot of nuisance "ponding," flooding of roadways, as well as the pretty rapid rise of stream and creeks, except for the rivers," said Santa Rosa Fire Department Marshal Paul Lowenthal. He does not expect swift water rescue teams to be called up.

Just two weeks ago, a Red Flag Fire Warning here had the fire department asking residents to clean out gutters and debris from their properties to minimize the potential spread of wildfires.  "Here we are now asking them to clear that same leaf litter in advance of wet weather to keep storm water flowing," said Lowenthal.

Then, there are the roads. "This storm is unusually big for the first, the first rain of the year," said CHP Lt. Ross Ingles. The California Highway Patrol is expecting more than the usual count of crashes, spinouts, rollovers and power pole strikes. 

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"The first rain of the year is traditionally when we get the most accidents. So, it pulls new oils up out of the roadway that's been building up through the dry months," said Officer Ingles.

Many will be caught up in what will be brought on by other drivers' excessive speeding, failure to maintain safe vehicle separation and unsafe maneuvering. "The two biggest things that are gonna help you avoid getting into an accident: slow down, increase your following distance, allow yourself time to stop in case there is some other driver who spins out and get into an accident in front of you," said Ingles.

Along with warning about the risk of flooding from the heavy rain, the weather service has also issued a Wind Advisory for most of the region that goes into effect at 10 p.m. Tuesday through 6 a.m. Thursday because of a risk of high winds that could lead to downed trees and branches and power outages.

Forecasters are saying there is also a chance of thunderstorms when a second round of rain rolls into the region on Friday and Saturday, and lingering showers are expected to last into early next week.

Bay City News' Dan Mcmenamin contributed to this story.