The storm that moved into the West Coast earlier this week will redevelop on the leeward side of the Rocky Mountains Thursday night, and will lead to a heavy snow for portions of the Northern Plains Thursday night into Friday before tapering off Friday night. This low pressure that forms is known as a “Colorado Low” because it develops east of the Rockies in Colorado and is known to rapidly strengthen. This low won’t be super strong with a minimum pressure in the 990s but it will bring gusty winds of up to 30-50 mph.
So beginning Thursday night, snow will break out across eastern Wyoming, portions of eastern Montana, western South Dakota, and western Nebraska. Freezing rain and sleet may also develop near and around the South Dakota/Nebraska border, which can make for very slick conditions for your Friday morning commute. This snow will also be falling at a moderate to heavy intensity based on the strength of this low pressure system, so the snow will add up fast, especially because snowfall ratios will be greater than the typical 10:1 ratio.
This will be a quick-hitting system with impacts peaking Friday morning. A heavy snow is expected to continue in portions of western South Dakota and Nebraska while a lighter snow falls in parts of eastern Wyoming and Montana. Freezing rain and/or sleet will continue in southeastern South Dakota and northeastern Nebraska through the mid-afternoon, so this region may receive as much as a quarter inch of ice accretion. Some of this freezing rain may also impact western parts of Iowa during the afternoon and evening hours. Speaking of the afternoon, the snow will start to become more spread out and scattered. This snow is expected to fall in parts of eastern Montana, northeastern Wyoming, and some areas of South Dakota and Nebraska.
Friday night, snow will clear out of the Northern Plains by midnight as the moisture works to the south and east. The snow in Montana will also clear out toward Canada. Meanwhile to the east, a wintry mix of snow and freezing rain is possible across much of Iowa into northern Illinois outside of Chicago.
By Saturday, all of the precipitation will clear out of the Northern Plains and Upper Midwest as our storm system races toward the East Coast. Some colder air may work into the northern part of the moisture associated with this storm, so a brief period of freezing rain or wintry mix cannot be ruled out across portions of the Ohio Valley into the central Appalachian Mountains.