A storm capable of producing blizzard conditions is taking aim at portions of Wyoming, Colorado, western South Dakota and northwestern Nebraska Friday.
Dry, tranquil weather over the Central states now will not hold through the end of the week. The storm and its rapidly changing weather conditions may catch millions of people off guard.
A storm responsible for bringing record rainfall to parts of the Northwest last weekend will blast areas from the Rockies to the Plains and Midwest with snow, wind, rain, severe thunderstorms and tornadoes into Saturday.
Difficult travel is likely along much of I-80 and I-25 in Wyoming and I-90 in western South Dakota with snow- and slush-covered roads and poor visibility. Rapidly accumulating snow, blowing and drifting may cause some ill-prepared motorists to get stuck or become disoriented. The storm could be intense enough to close some roadways for a time.
Wind gusts of 40 to 60 mph, both with and without heavy snow, can also down trees and power lines.
Cities in the path of the storm and potential blizzard include Rapid City, S.D., Chadron, Neb., and Cheyenne and Casper, Wyo.
A push of cold air from Canada colliding with warmth and moisture will bring snow to the northern Rockies and rain changing to snow, followed by blizzard conditions to some areas of the High Plains.
Cold air will wrap in behind the reorganizing storm across Montana, Wyoming and northern Colorado. Strong winds and/or heavy snow will reach some areas hit by heavy snow last week and some locations hit by flooding earlier during September.
The storm will strengthen greatly east of the Rockies Friday. As this happens, rain will become mixed with and change to snow in some locations of the High Plains.
Blizzard conditions will center on the Black Hills of South Dakota. However, accumulating snow could reach as far to the east as central South Dakota and southeast into central Nebraska.
Accumulating snow may reach just north and west of Denver, Colo. A slight shift in the storm track could bring accumulating snow to Denver.
While it may be just a tad too warm for an all-out major snowstorm in areas farther east in Nebraska, the Dakotas and Minnesota, snow can mix in at times in these areas Friday night and Saturday.
Across Colorado, some ski resorts are taking advantage of the cool weather and are already making snow. In preparation for the 2013-14 ski season, Loveland Ski Area and Arapahoe Basin Ski Area plan to make snow for as long as conditions allow, according to a press release by Colorado Ski Country USA (CSCUSA).
Across southeastern Nebraska, Iowa and southern Wisconsin, the air will be too warm for snow, but powerful thunderstorms are a concern. Gusty winds will also be a factor.
As high pressure builds in the wake of the storm over the West, a Santa Ana event could bring damaging winds and raise the risk of wildfires in Southern California late in the week.
Temperatures will rebound and much of the snow at lower elevations will melt over the weekend.