California’s ski resorts are digging out from under 5 to 9 feet of snow that has fallen over the last several days from a series of storms. And more snow is on the way.

A large dip, or trough, in the jet stream across the West is allowing frigid conditions and a relentless series of storms to bring record-breaking snowfall into the Sierra Nevada Mountains. The snow has closed major interstates and even forced the shut down of several ski resorts.

According to the National Weather Service, between 6 and 9 feet of snow has fallen in the Sierra Nevada Mountains since Wednesday. Northstar California Resort picked up 15 inches of new snow since Monday.

Some one-week snowfall totals may eclipse 10 feet as more storms bring additional rounds of snow through Wednesday.

At UC Berkeley’s Central Sierra Snow Lab, 202.1 inches have fallen in December, making it the snowiest such month on record there, and the third-snowiest month of all time.

In addition to the snow, much of the West, including Seattle and Portland, Oregon, are experiencing unusually cold conditions, as an Arctic air mass seeps across the Canadian border. The Weather Service warned of the potential for hypothermia and frostbite in Seattle, where overnight lows have hovered near 20°F.

In Portland, even colder temperatures are expected again Tuesday night on the eastern side of the city, as air temperatures plummet in the Columbia River Gorge. Wind chills could hover close to 0°F, and there is a risk of pipes bursting in homes, the Weather Service warned.