LAKE COUNTY, Calif. — The last in a series of nine storms that began at Christmas is forecast to arrive midweek, and then California can expect some dry weather.

“We’re finally getting through the parade of storms,” State Climatologist Dr. Michael Anderson said in a Monday briefing.

Anderson said there is a change in atmosphere with high pressure building in the Pacific, which will lead to colder air coming into California.

The next storm is expected to arrive on Wednesday and continue to Thursday. It will be the ninth storm since Christmas, but the 10th atmospheric river, as Anderson explained that the eighth storm, which occurred from Friday through the weekend, included two atmospheric rivers.

After the ninth storm takes place, Anderson said the forecast calls for dry conditions through the end of January.

The forecast for this week shows the ninth storm will bring between a quarter of an inch to an inch and a half of rain across Lake County before conditions clear up.

Anderson said this next and last storm “just barely qualifies” as an atmospheric river, explaining that it will only be an atmospheric river for a six-hour window. It will move from the north to the south, and will be fairly limited in how much moisture it brings. There will be no rain south of Santa Maria, he added.

Anderson said there is now a transition from the storms to high pressure that’s building over the Pacific, changing the storm track for the ninth storm forecast for Wednesday and limiting the moisture it will transport.

With a break in the rain over the last few days and drier conditions in the forecast, Anderson said rivers are receding in most locations but will sustain high flows as water works its way through watersheds. At the same time, there are reservoir releases in parts of the state as part of flood control measures.

“Where's starting to see rivers working through their final crests,” he said.

The California Nevada River Forecast Center showed that on Monday night 19 river and water systems were above monitor stage and only one location, on the San Diego River in Southern California, was above flood stage.

As officials had predicted, areas on the Russian River in Hopland and Guerneville, which had been in flood stage last week and into the weekend, were back in normal conditions.

In Lake County, the U.S. Geological Survey’s gauge on Clear Lake shows that the lake’s level began to actively rise late on Dec. 26, at which point it was about -2.34 feet Rumsey, the special measure for Clear Lake.

Since then, Clear Lake has risen about 6 feet, hitting 3.63 feet Rumsey late Monday. However, the increase in lake height has started to slow and level out thanks to the break in rain. Clear Lake is considered full when it reaches 7.56 feet Rumsey.

In eastern Lake County, Indian Valley Reservoir also has shown substantial inflow since Christmas. The U.S. Geological Survey’s report on the reservoir showed that it had risen from 45,180 acre feet on Dec. 26 to 106,600 acre feet on Monday.

Yolo County Flood Control and Water Conservation District’s last report on Indian Valley Reservoir, issued on Jan. 12, showed that at that point it was at 91,452 acre feet, compared to 44,970 acre feet on the same day in 2022.

Anderson said that, climatologically, the state is hitting the second of its winter astrological peak tides, or “king tides,” which are expected this weekend.

The California King Tides Project explained that the first of the two king tides occurred Dec. 23 and 24.

Snowpack at ‘epic levels’

In addition to the rain brought from one storm after another, the Sierras and other mountain regions of the state now have a large amount of snow.

Anderson said the state’s snowpack is at “epic levels.”

The California Data Exchange Center reported on Monday that the statewide snowpack in the Sierras was at 247% of normal, which breaks down to 209% in the north, 246% in the central region and 288% in the south.

Anderson said California’s current pace with snowpack puts it ahead of the 1982-83 snowpack, which holds the record since snowpack levels began to be recorded in 1950.

“Big difference is, we’re going to hit a two-week stretch of dry weather,” Anderson said.

He said the last really good snowpack was in 2019. That year, the snowpack was the fifth largest recorded.

Anderson said the abundance of snow sets the stage for potentially dealing with flood issues as snowmelt season arrives in some water basins. He said many areas have pivoted from drought to dealing with flood releases from reservoirs.

Peak snowmelt depends on how the spring plays out, how quickly things heat up and how many clear, sunny days there are. “It’s that direct solar radiation that really changes snow and makes it ready to melt,” Anderson said.

Peak melt in the Sierra typically runs from April to early July, he said.

At the start of winter, Anderson said a La Niña — which tends to bring drier conditions — was in place. By Christmas, the strength of the La Niña event had started breaking down.

What began then, Anderson said, was a transition into “neutral conditions.”

The National Oceanic and Atmospheric Administration explains that neutral conditions are when sea surface temperatures are generally close to average and between El Niño, which is a warming of the ocean surface, and La Niña, which is when the ocean surface is cooling.

Anderson said neutral conditions are expected in the coming months. “As you move into neutral conditions, you lose the reinforcement of that high pressure ridge which had been in place before Christmas,” he said.

That will lead to a fluctuation between that high pressure ridge and the jet stream, which will determine whether storms make it into California, Anderson said.

He said there is much less predictability when in a transition state rather than when it’s in one state or another — El Niño or La Niña.

Reservoirs continue filling up

The storms have had another major impact — they’ve been helping to fill up California’s network of 154 reservoirs.

On Monday, Molly White, State Water Project water operations manager, said the total statewide storage was at 91% of the historical average, an improvement of about 10% since last week.

Lake Shasta surpassed 2.3 million acre feet of water on Sunday, putting it at 51% of capacity and 81% of its historical average, White said.

White said Lake Oroville on Monday was just shy of 2 million acre feet, which also puts it at 51% capacity but at 101% of its historical average, and surpasses the lake’s 2021 and 2022 peak storage.

Lake Oroville has roughly 600,000 acre feet of storage available before a release of water will be necessary for flood control, White said.

In neighboring Mendocino County, Lake Mendocino’s level has risen to 148% of its historical average, according to the California Department of Water Resources. The lake has 122,400 acre feet of storage and was at 95,839 acre feet on Monday.

The United States Army Corps of Engineers San Francisco District reported that Lake Mendocino has increased almost 40 feet in depth over the past month.

As a result, the U.S. Army Corps began a series of high-flow releases from Coyote Valley Dam at Lake Mendocino starting midday on Monday in response to reservoir levels and improving downstream conditions on the Russian River.

The releases are meant to make room for additional rainfall this season.

“This approach will safely accommodate additional storm inflows, and sustain lake levels for boating and other recreation,” the agency said on the Facebook page it manages for Lake Mendocino.

The Army Corps said the release was timed “to allow downstream river levels to recede while still allowing for as much time as possible to evacuate water from the dam prior to the next storm.”

INFORMATIONAL LINKS:

U.S. Geological Survey gage on Clear Lake:
https://waterdata.usgs.gov/monitoring-location/11450000/#parameterCode=00065&period=P30D

U.S. Geological Survey gage on Indian Valley Reservoir:
https://waterdata.usgs.gov/monitoring-location/11451290/#parameterCode=00054&period=P7D

Yolo County Flood Control and Water Conservation District report on Indian Valley Reservoir:
https://www.ycfcwcd.org/waterinfo.html

California Nevada River Forecast Center
https://www.cnrfc.noaa.gov/

California Data Exchange Center Snow Water Equivalents page:
https://cdec.water.ca.gov/snowapp/sweq.action

California King Tides Project link:
https://www.coastal.ca.gov/kingtides/

Information on El Niño and La Niña:
https://www.weather.gov/mhx/ensowhat#:~:text=Neutral%3A%20Neither%20El%20Ni%C3%B1o%20or,along%20(or%20vice%20versa)

California Department of Water Resources Daily Reservoir Storage Summary page:
https://cdec.water.ca.gov/reportapp/javareports?name=RES

Lake Mendocino Facebook page:
https://www.facebook.com/LakeMendocino

Email Elizabeth Larson at This email address is being protected from spambots. You need JavaScript enabled to view it.. Follow her on Twitter, @ERLarson, or Lake County News, @LakeCoNews.