Update, 7:30 a.m. Wednesday:The California-Nevada River Forecast Center's latest estimate of the Russian River's crest at Guerneville says the waterway will peak at about 5½ feet over flood stage. That's down 2 feet from the forecast last night for a 39.8-foot crest, which would have significantly widened the inundated area. The CNRFC's next forecast is due out at 9 a.m.
Update, 10:35 p.m.: The California-Nevada River Forecast Center has updated its forecast for flooding on the Russian River at Guerneville -- and it's not good news for communities along the waterway's lower reaches.
The new forecast, released after 9 p.m., estimates the river will rise to 39.8 feet by Wednesday evening, then recede to below flood level Thursday afternoon. The new forecast is 7.8 feet above flood stage.
Earlier in the day, Sonoma County issued an evacuation advisory based on a flood level of 38.3 feet and estimated about 100 structures would be affected, on top of the 550 that have already been flooded. We don't have a figure yet on how many additional homes and businesses could be in the water as the flood approaches 40 feet. Here's a snippet from the general description of flood impacts from the river forecast center:
39.0 Feet: Significant flooding is expected to occur along the lower portions of the Russian River. River Road, along with a few houses, will flood at the town of Hacienda. Armstrong Woods Road, 4th Street, and Mill Street are forecast to flood. The village of Northwood Grove and Monte Rio School are expected to become inundated.
40.0 Feet: Major flooding is expected along the Russian River. Many roads in Guerneville, Monte Rio, Rio Nido, and Hacienda will be flooded.
Update, 9:30 p.m.: Downpours throughout the Bay Area prompted a series of flash flood warnings and ongoing worries about flooding along the Russian River.
During the day, flood warnings or flash flood warnings were in force through Wednesday morning for dozens of communities in every Bay Area county as prolonged heavy rain fell on terrain already saturated by storms last week and over the weekend.
The National Weather Service issued flash flood warnings as creeks rose rapidly in parts of Sonoma, Marin, Napa, Alameda, Santa Clara and Santa Cruz counties. Early Tuesday evening, flood sirens warned residents in flood-prone areas of the Marin communities of Fairfax, San Anselmo and Ross to move to higher ground as local creeks reached capacity.
As the main body of Tuesday's storm passed to the east Tuesday evening -- yes, it really looks like the pounding is over for the time being -- Sonoma County still appears to have suffered the most severe impacts of the deluge.
The county lists 45 road closures due to flooding, slides and downed trees or power lines. Large swaths of agricultural land are under water. County officials say that at least 550 homes and businesses near the Russian River near Guerneville have been flooded -- a number expected to grow by at least 100 as the river reaches a crest forecast to be 6 feet over flood stage on Wednesday evening.
Scattered showers are expected overnight into Wednesday, followed by a weaker storm Thursday that could still drop another 1 to 2 inches at the Bay Area's wettest locations.
Some precipitation highlights for the 24 hours ending at 9 p.m. Tuesday:
Venado (Sonoma County): 6.40 inches Kentfield (Marin County): 6.11 Boulder Creek (Santa Cruz Mountains): 5.24 inches St. Mary's College (Moraga): 5.02 inches Vollmer Peak (Berkeley Hills): 3.30 inches
Urban totals include:
Santa Rosa: 2.92 inches San Rafael: 3.86 inches Richmond: 1.96 inches Downtown San Francisco: 1.21 inches Oakland International Airport: 1.53 inches San Jose International Airport: .60 inches
Original post: Another day, another relentless rainy torrent.
Our third major storm of 2017, fueled once more by subtropical moisture, has dumped heavy rain across most of the Bay Area. Occasionally heavy precipitation is expected to continue late into the evening before breaking up into scattered showers Wednesday.
The major concern in the region is flooding, and much of the attention is focused in the North Bay, especially the lower Russian River in Sonoma County. During the course of the day, the National Weather Service issued flood and flash flood warnings for large swaths of the county, including areas near Healdsburg, Geyserville, Sebastopol, Santa Rosa, Petaluma and the town of Sonoma. On the other end of the Bay Area, the service issued a flash flood warning for parts of Los Gatos as Lexington Reservoir reached capacity and sent water into Los Gatos Creek.
In western Sonoma County, the Russian River crested at 3 feet above flood stage in Guerneville on Monday, flooding hundreds of homes and businesses in the resort town and nearby communities. After the river receded to just above flood stage today, the California-Nevada River Forecast Center says the Russian is expected to rise to about 6½ over flood stage by Wednesday evening, inundating even more property.
After a brief break from the major weekend storm, heavy rain resumed across the watershed late Monday and continued without respite Tuesday.
Among locations widely watched for gauging the intensity of rainfall that will wind up as runoff cascading into the Russian River are Venado, in the hills west of Healdsburg, and Cazadero, in the hills north of the river near the community of Duncans Mills.
For the month so far, Venado has recorded about 24 inches of rain for a total of 69.48 inches since Oct. 1, the start of California's official water year.
Unofficially -- meaning from our own reading of Department of Water Resources and National Weather Service numbers -- that ranks Venado as No. 3 on the list of rainiest places in the state so far this water year. No. 1 appears to be Four Trees, a place in the mountains of Plumas County, which had gotten 73.52 inches as of midnight Monday; No. 2 is the Mattole River hamlet of Honeydew, in western Humboldt County, with 70.24