California Is About to Get Pounded With an Atmospheric River, Raising the Risk of Mudslides

Image: Colorado State University

A series of monster storms will leave California’s mountains white and set rivers roaring over the back half of the week. The Golden State is looking at feet of snow and hurricane-force winds, and because of all the areas burned by record-setting fires the past two years, a serious risk of mudslides.


California’s winter is when the state picks up most of its precipitation. So far, it’s been pretty hum drum, but that’s all changing. The first blast of rain and snow hit over the weekend as a warm up for the main event, which commenced Tuesday night when an area of swirling low pressure began unleashing rain and snow. By sunrise on Wednesday, clouds spanned the entire West Coast, with a long tail running of moisture running all the way to the tropics.

That tropical connection is a classic setup for an atmospheric river event, sometimes known as a Pineapple Express. Air currents pick up moisture from that equatorial well and carry it to the West Coast, where it can produce eye-popping snow totals.

The light blue shows the moisture plume driving the atmospheric river ashore in California.

California ski resorts are forecasting up to eight feet of snow could fall by Sunday. Early returns already look promising with Tahoe resorts picking up a foot overnight from Tuesday into Wednesday. Further south, Mammoth Mountain reported 15 inches. Even a few inches have fallen at Mountain High in Southern California.

It’s not all fun and powder days, though. Winds whipping over the mountain ridges could also lead to whiteout conditions, with gusts expected to top out at 110 mph. The National Weather Service is also warning of pounding surf up and down the coast.

While no attribution analysis has been done on this particular atmospheric river, climate change is projected to make these types of events more intense. That’s especially problematic since climate change is also making large wildfires more destructive.


In California the Thomas, Wine Country, Mendocino Complex, Carr, Camp, and Woolsey fires are just some of the blazes that have all burned major acreage over the past two years. That’s left nude hillsides susceptible to mudslides when it rains as hard as it’s supposed to this week. Last winter, deadly mudslides in Southern California swept through the area scarred by the Thomas Fire in wake of major rainfall. This atmospheric river poses a similar threat. The National Weather Service has issued a flood watch that “includes possible flooding of small rivers and creeks, and possible mud slides or debris flows within the Carr, Delta and Hirz burn scar areas.” A similar warning is in place in the foothills of Southern California around the Holy Fire burn scar.

People are still trying to get their lives back together after last year’s fires. This week’s weather is a reminder of the injustice of climate change-fueled blazes and a more frenzied atmosphere in a warming world.


Managing editor at Earther, writing about climate change, environmental justice, and, occasionally, my cat.



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