AccuWeather meteorologists say that an active pattern is ramping up across the Western U.S. this week that can pull in brisk, Arctic air and promote areas of heavy mountain snow. In the upper levels of the atmosphere, the jet stream will begin to plunge southward during the first half of the week, which will help usher in a large storm to the Northwest.
To start the week, conditions across the West can be somewhat mild for many locations compared to what will arrive by midweek. However, temperatures can stray between 3-6 degrees Fahrenheit below the historical average in many Northwest towns and cities on Monday, including Eugene, Oregon, Billings, Montana and Seattle.
A swiftly moving clipper storm and its associated frontal boundary will swing through parts of the northern Rockies into the Upper Midwest and Great Lakes region from Monday into Tuesday. As this feature traverses across the northern tier of the Western and Central states, it will begin to pull chilly, Arctic air southward into the United States from Alberta and Saskatchewan. Nature will start to give the West hints of what is to come, lowering temperatures by a few degrees on Tuesday across parts of Washington, Oregon, Idaho and Montana.
Another storm will follow closely behind the clipper storm, arriving in full force Tuesday in the Northwest. All eyes will be on this segment as it is expected to track southward and deepen as it brings cooler air, snow and gusty winds and as far south as the Four Corners.
“We could see disruptive high winds develop across the prone locations early this week, such as Marias Pass, Livingston, Montana, southeastern Wyoming and portions of the Front Range, where winds can gust as high as 80 mph,” explained AccuWeather Meteorologist Brandon Buckingham.
Forecasters warn that strong winds across these areas on Monday and Tuesday can increase travel times along area roadways and interstates, such as interstates 25, 70, and 80 in Wyoming, Utah and Colorado.
As the gusty winds expand southward from Montana to Colorado, the blustery conditions will be accompanied by periods of snow across the spines of the Northern Rockies and, eventually, the Colorado Rockies. Occasional snowfall will focus across the higher terrain of the Washington Cascades and the Rockies in Idaho, Montana and northern Wyoming on Monday. By Tuesday, periods of snow will reach southward into parts of Oregon, Northern and Central California, Nevada, Utah and Colorado while also persisting in the northern Rockies.
In Salt Lake City, rain showers are expected to shift over to snow throughout the day on Tuesday. Overnight on Tuesday, conditions will gradually transition over to periods of snow, which can persist through Wednesday and total 6-10 inches. Snow levels will lower on Tuesday in places like Reno, Nevada, as well, dropping to 5,200 feet by the afternoon.
As the storm plunges southward into parts of the Southwest late Tuesday into Wednesday, a dramatic temperature shift will occur from Montana to Utah and Colorado as brisk air is pulled from Canada.
“Temperature readings can drop quickly, likely falling between 20-40 degrees over 24 hours for most locations,” said Buckingham.
In Billings, Montana, high temperatures on Wednesday may only reach -4 F, a noticeable difference from the forecasted Tuesday daytime high of 35 F. Similarly, in Casper, Wyoming, daytime highs from Tuesday to Wednesday can shift from 41 F to 1 F, respectively.
Other notable shifts in temperature from Tuesday to Wednesday can be Denver and Salt Lake City. Salt Lake City can observe a 24-hour temperature change of 17 F, while Denver can drop to around 29 F heading into midweek.
Snow will continue to spread southward along the Sierra Nevada Range, mountains in Arizona and New Mexico through Wednesday night. In Arizona, the highest snowfall accumulations ranging from 6-12 inches, are likely to dominate portions of the Kaibab Plateau, White Mountains and Mogollon Rim. Similarly, the highest peaks of the Sierra Nevada could observe amounts ranging from 6-12 inches from Tuesday to Wednesday.
In the highest elevations of the Cascade Range, northern Rockies and Colorado Rockies, snowfall amounts can total up to 18-24 inches from Sunday to Wednesday with the AccuWeather Local StormMax
of 60 inches.
As this feature gradually tracks east of the Rocky Mountains from mid- to late week, it will continue to spread a swath of snow and the threat for ice from the Great Lakes to even areas of the Northeast. Forecasters will continually be watching this storm as it progresses across the country this week, and users are urged to monitor AccuWeather for updates as they become available.
Produced in association with AccuWeather.
