A winter storm system could bring a rare white Christmas to parts of the U.S., with some grappling with the possibility of snow piling up to 10 feet high.
The incoming storm is expected to hit regions in close proximity to sea level, including Oregon and Washington states, according to the National Weather Service.
Meanwhile, heavy snowfall is expected in the central Sierra Nevada Mountains, where snow could pile up as high as 10 feet.
Most residents in the Sierra Nevadas are expected to see around five to eight feet of snow, with people urged to avoid travel over the coming days due to potentially hazardous driving conditions.
“A series of Pacific storms will bring periods of heavy low elevation rain and heavy mountain snow to the Western U.S. through the Christmas weekend,” the National Weather Service said in a tweet on Wednesday.
It also warned that flash flooding and debris flows were possible in the vicinity of recently burned areas.
For cities like Portland and Seattle, the development means they could see a rare white Christmas this year.
“More and more weather models suggest enough cold air and moisture will overlap across the region to produce accumulating snow to near or at the valley floor beginning Saturday night and continuing into Monday,” the National Weather Service in Portland said in a tweet on Wednesday night.
The weather service said “additional rounds of snow are probable next week” as well.
In a separate tweet, the National Weather Service in Seattle said “widespread heavy snow is NOT expected through Christmas Day.” However, it said some snowfall was possible.
If Seattle does see snow, the weather service said it would be most likely to fall on Saturday evening through Sunday night.
“Much of the lowlands could see 3-5″ of snow in the most likely scenario,” it said.
The weather service said that in the span of 127 years, Seattle has recorded “measurable” snowfall on Christmas day just seven times, with 1909 seeing the most snow at 1.8 inches.
For much of the U.S., a white Christmas appears unlikely this year.
As of Thursday, data from the National Oceanic and Atmospheric Administration showed that just 26 percent of the country was covered by snow, excluding Alaska.
The technical definition of a white Christmas in the U.S. is one inch or more of snow on the ground on Christmas day, according to the National Weather Service.