Blizzard moves in tonight through Saturday night
Before the snow moves in, a quick period of freezing rain and sleet are expected do develop across western South Dakota. The wintry mix will quickly transition over to snow and become heavy through the evening and overnight hours. Winds will be increasing overnight as well with gusts reaching 50 mph or higher by morning.
Snow will remain moderate to heavy for many during the day Saturday. Wind speeds are expected to peak on Saturday, too, with gusts reaching 60 to 65 mph by midday. Snow totals by Sunday morning are expected to be anywhere from 6" to 12" of snow for many, with those in the northern hills and other isolated locations seeing up to 24" or more. The wind will make it difficult to get accurate snow totals, but drifts will likely exceed 36" for many.
Blowing and drifting snow will create significant impacts to travel and likely make it impossible across much of western South Dakota and northeast Wyoming. Many, if not all flights in and out of Rapid City Regional Airport will be cancelled on Saturday and potentially into Sunday, especially during the morning hours.
Expect roads to remain snow covered and slippery through much of Sunday. Travel will be very difficult Sunday, but probably not impossible. If you must travel, prepare an emergency kit for your vehicle. Pack water, food, warm clothing/blankets, kitty litter or sand for traction, a way to charge cellular devices and always have a full tank of gas. It is highly suggested to not even attempt to travel Tonight through Sunday morning at least.
A thin coating of ice and snow may add weight to tree branches and power lines. The significant winds on Saturday could snap branches or knock down power lines, which would create power outages for some. Prepare accordingly. Be safe and stay warm this weekend.