Avalanche Warning Issued for 5 States as Deadly Atmospheric River Arrives

An avalanche warning has been issued for five states as a deadly atmospheric river makes its trek eastward.

The atmospheric river arrived in California on Sunday and wreaked havoc with severe rain, snow and high winds. The storm followed a similar system that brought a deluge of rain to the state last week, leading to saturated ground prone to flooding with the second system.

Catastrophic flooding did occur, particularly in Los Angeles, where more than 7 inches of rain fell. Now, meteorologists are worried that the storm could cause avalanches as itcreates hazardous conditions in mountainous states.

Atmospheric rivers are a "long, narrow region in the atmosphere—like rivers in the sky—that transport most of the water vapor outside of the tropics," according to the National Oceanic and Atmospheric Administration.

On Thursday morning, the National Weather Service (NWS) issued avalanche warnings for Idaho, Montana, Utah, Colorado and New Mexico.

"Intense snowfall and strong winds have created very dangerous avalanche conditions. Large and deadly avalanches will be very easy to trigger. Avalanches will run naturally," the NWS office in Boulder, Colorado, said in the warning.

NWS meteorologist Zack Taylor told Newsweek that energy associated with the atmospheric river has now moved into the intermountain west and the Rocky Mountains. The storm is bringing heavy snowfall to high-elevation areas.

"Heavy snowfall and strong winds create favorable avalanche conditions," Taylor said, adding that the risk will persist for the next few days before the system moves into the central and eastern United States.

Mountains at risk for avalanches are those in the Centennial Mountains, the Lionhead area near West Yellowstone, the southern Madison and southern Gallatin ranges in Montana; the Park Range, Ruby Range, West Elk Mountains, Flat Top Mountains, Grand Mesa, San Juan Mountains and the Sangre de Cristo Range in Colorado, the Wasatch Range, western Uinta Mountains, Wasatch Plateau and Skyline Mountains, and several ranges in southwestern Utah; and the Wheeler Peak Wilderness Area and Columbine Hondo Wilderness in New Mexico.

"New and wind-drifted snow are overloading an exceptionally weak snowpack, creating very dangerous avalanche conditions. Human-triggered and natural avalanches are likely. Avoid avalanche terrain and avalanche runout zones. The avalanche danger is HIGH on all slopes," the Gallatin National Forest Avalanche Center said in a warning.

The Utah Avalanche Center warned that "people will be able to trigger avalanches for a distance without even getting onto a steep slope.

"Other avalanches will happen spontaneously and crash down on their own," the warning said. "Avoid being on or under any steep slopes. Please spread the word about these deadly conditions."