A late season winter storm bringing up to 24 inches of snow to the Sierra Nevada mountains this weekend could prompt California water officials to release water from some of the state's reservoirs for flood prevention.
Widespread amounts of more than 12 inches of snow are forecast for the high-elevation Sierra Nevada mountains this weekend, with possible locally higher amounts between 18 and 24 inches. Lower elevation areas are expecting rain. The storm comes at the start of the state's dry season and could serve as one last boost to major reservoirs before dry weather takes hold.
California's reservoirs reached concerningly low levels in the summer of 2022 after battling years of drought, but an abnormally wet winter last year helped alleviate that problem. At the start of the year, snowpack levels were much lower than expected, but the snowpack recovered earlier this year after a series of atmospheric rivers brought torrential rain and heavy snowfall to the state. Snowpack was above average by the time it began melting in April. However, despite being more than a month into spring, more snow is on the way to California and could cause more influx to the state's reservoirs right before the dry season begins.
Atmospheric rivers are likened to rivers in the sky, and when they make landfall, they cause torrential rain and sometimes snowfall.
NWS Weather Prediction Center meteorologist Bob Oravec told Newsweek that May is the start of California's dry season, and that late season snow will help supplement the reservoirs.
California receives 30 percent of its fresh water supply from snowpack melt, which begins in April. Many of California's reservoirs are already near capacity—much above average for this time of year—and the influx of water this weekend could cause some water officials to release water for flood operations, Oravec said.
For example, the California Department of Water Resources (DWR) is currently releasing water from Lake Oroville at 4,000 cubic feet per second. That could change this weekend.
"Light precipitation is forecast this weekend with dry weather following. DWR may increase releases starting Friday to account for elevated inflows into the reservoir," a DWR spokesperson told Newsweek.
The storm comes as the (DWR) transitions to capturing the water rather than releasing it during the wet season.
Throughout April, DWR has decreased total releases from Lake Oroville to account for reduced inflows into the reservoir," the spokesperson said. "As the warm, summer months approach and rain and snowstorms driven by atmospheric rivers wane, DWR transitions from performing flood control releases at Lake Oroville, as required by the U.S. Army Corps of Engineers' Water Control Manual, to capturing as much water in the reservoir as possible while still meeting water delivery and environmental requirements.
"DWR continues to monitor lake and snowpack levels to optimize water storage and allow for carryover storage into next year," the spokesperson added.
As of Wednesday, Lake Shasta and Lake Oroville—the state's two largest reservoirs—were at 96 percent capacity and 98 percent capacity respectively.
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Anna Skinner is a Newsweek senior reporter based in Indianapolis. Her focus is reporting on the climate, environment and weather ... Read more
