A pair of powerful storms - one hitting Southern California and the deserts with heavy rain, the other striking the Northwest with rain and snow - are forecasted to merge over the central United States during the Christmas weekend.
Their collision will likely cause an extended period of accumulating snowfall and hazardous travel conditions across parts of the Rockies and Plains.
Meteorologists closely track the storms’ movements to pinpoint which areas may see the worst impacts. Before merging later in the week, the separate storms will initially bring pockets of snow to the southern Rockies and interior Northwest.
However, warm air over the region will keep snow levels high, meaning precipitation may start as rain even in typically snowy spots like Boise, Flagstaff, and Salt Lake City.
Although beneficial for ski resorts in the northern Rockies thanks to fresh powder, the snow could make travel to higher elevations difficult amid expected blizzard conditions on mountain passes.
Lower elevations farther east may also face significant hazards if the storms combine quickly into a more powerful system.
Heavy Snowfall Predicted For Parts of Rockies and Adjacent Plains
As the pair of storms gradually merge over the weekend, colder air blowing over the West's interior will likely change rain showers to snow, with accumulations working their way down from mountaintops to intermediate elevations and possibly valley floors in spots.
After initial rain, a few inches of snow could amass on Arizona's central and northern mountains.
But accurately predicting snowfall farther east depends on the speed at which the separate storms consolidate, as faster fusion would rapidly drop temperatures below freezing and switch precipitation to all snow outside of the Rockies.
Later on the holiday weekend, a swath of heavy snow may stretch along Interstate highways in Colorado, Wyoming, Nebraska and the Dakotas from Saturday through Monday.