As cold air continues to filter into the western portion of the nation, rain, snow, and wind will impact many through the end of the year.
Snow levels will gradually fall through the day on Sunday leading to several inches of snow in the higher elevations of the Pacific Northwest and Intermountain West by Monday morning.
While mostly rain will fall along I-5 in Washington and Oregon, snowflakes can mix in to sea level in the Puget Sound area, including Seattle. There could be a slushy coating of snow on some of the hills in the region by Monday morning, before sunshine returns.
A more significant story as the week begins will be the unseasonable cold across the West. As a cold front sweeps through the region to begin the week, temperatures will be well below normal for many.
AccuWeather.com Meteorologist Dave Samuhel stated "Parts of Montana will not be above zero for a day or two early next week. However, the core of the cold will not reach Seattle and Portland, so there is not a concern for a high-impact winter weather event in the I-5 corridor in the Pacific Northwest."
This cold will sink into the Southwest through the beginning of the week. The incoming cold combined with an upper-level disturbance in the Southwest will bring the threat for wintry precipitation to unusual places by the middle of the week.
"Unusually cold air will target the southwestern U.S. by midweek. Las Vegas has not seen measurable snow since December 2008 and there is a chance they see measurable snow," said Samuhel.
As the upper-level storm spins over the Southwest, the threat for snowfall will also be found in the higher elevations surrounding Los Angeles. "Snow levels will be down to 2,500 feet (by midweek) and the Antelope Valley in the upper deserts outside of Los Angeles could have measurable snow as well," continued Samuhel.
Travel will be slowed in the higher elevations midweek where snow will fall. Snow-covered roads and slippery travel can be expected.
This cold regime will be firmly entrenched across the West through the new year, so New Year's Eve festivities will be on the chilly side for many in the West.
By Ed Vallee, AccuWeather.com Meteorologist