California is bracing for another atmospheric river, which is set to bring heavy rain and snow throughout the state. Although rain had already started to fall in some parts of Northern California on Wednesday, the main event is expected to occur on Thursday, with the heaviest precipitation likely to fall on Thursday night into Friday. The ground is already saturated in many parts of the state, and flooding risk remains very high until Sunday.
Atmospheric rivers, which have picked up moisture near Hawaii, have a larger impact than an average rainstorm. They blow towards the Western U.S. and can dump rain and snow for days, leading to flooding, mudslides, sinkholes, and avalanches in some areas. With snowpack sitting a low elevations, this warm storm could bring high-elevation rain, which is typically how floods occur.
“This amount of rain falling on top of a 20-30 foot snowpack, and feet down to 3000 feet, is a recipe for disaster,” wrote storm chaser Carter Murphy on Twitter. “This is how you get floods like Jan 1997. People wait too long to make a big deal about this stuff.”
Absolutely insane 72 hour totals pic.twitter.com/6OPV8oKZ77— Carter Murphy ?8?? (@cartermurphy218) March 9, 2023
Rivers are expected to flood throughout the region during this event. Some dams have begun releasing more water to accommodate the flows, which could see rivers rising through the weekend. Officials even predict the use of the Lake Oroville spillway this week, which famously collapsed during a heavy storm in 2017. Here’s a map of the predicted floods:
Significant rises expected on many Nrn and Central CA Rivers late Thursday into the weekend as a warm and wet weather system moves through the area. Numerous forecast points are expected to exceed monitor and flood stage. Latest river forecasts at: https://t.co/CLLzb7f8tY #cawx pic.twitter.com/Zm5sCiv1G2— NWS California-Nevada RFC (@NWSCNRFC) March 8, 2023
Not only is flooding a concern, but winds could also cause some dangerous conditions throughout the region. Forecasts in Eureka and South Lake Tahoe predict 60 mph winds, with some models showing 100+ mph at high elevations of the Sierra.
The Sierra Nevada mountains and surrounding communities in Northern California were under a winter storm warning through the weekend. The region could receive between two and five feet of snow from Thursday to Sunday, with heavy rain and snow mixed with high winds potentially making driving treacherous. Warm temperatures also increase the risk of avalanches in areas where there is deep snow.
The snow has been consistently falling since October, with December and January seeing plenty of snowfall. After a brief pause in the beginning of February, Mother Nature returned with a vengeance and brought a series of storms that dropped over 10 feet of snow in two weeks. Then, March put the icing on the proverbial cake with over 100 inches in just a week. Many ski resorts have already seen 500 inches of snow this winter, with a few approaching the coveted 700-inch mark.
The public is advised to take precautions and stay updated on the latest weather conditions. Stay safe, NorCal.