The missing individual had not been found by midday Thursday. The National Weather Service in an updated outlook Friday said "significant" snowmelt flooding is likely in the valley.
Thirteen tornados were reported on Thursday in Kentucky, Indiana and MI, said Bob Oravec, a meteorologist with the National Weather Service's Weather Prediction Center in College Park, Maryland, but there were no immediate reports of serious damage. It said the plant continued to operate safely and there was no threat to plant employees or to the public. Residents of Avoca, Iowa, were filling sandbags to keep floodwaters from spreading, and the American Red Cross set up a shelter for anyone who was displaced.
South Dakota's governor closed all state offices Thursday as the blizzard conditions moved in, while wind, blowing snow and snow-packed roadways made travel treacherous in western Nebraska.
In Wolf Creek Pass, near the New Mexico border, has recorded 45 inches of snow.
The storm left quickly rising floods in its wake in parts of eastern Nebraska and Iowa that saw residents evacuated from their homes, roads washed out in communities, and farmers anxious all the water would drown livestock. Colorado Gov. Jared Polis declared a state of emergency, and more than 74,000 customers in Colorado remained without electricity on Thursday afternoon.
Lennox, South Dakota, Mayor Tracy West says there's a lot of water around and "it's got to find a way to get out of here".
The blizzard, bringing severe snowfall, poor visibility and powerful winds, caused hundreds of flight cancellations and thousands of power outages in Colorado and Texas.
A wind gust of 92 miles per hour (148 kph) was recorded in the mountains northwest of Denver.
Parts of seven states were under blizzard warnings, and 20 states were under some level of high wind alert, Carbin said. The president also praised first responders and emergency response teams for doing "a great job dealing" with flooding, high winds and road closures.
Wednesday's explosive development of a late winter storm over eastern Colorado created rough times for people both on land and in the air. And in New Mexico, 36 miners at a nuclear waste repository were trapped underground in an elevator for about three hours because of a power outage caused by the extreme weather.
The storm also contributed to the death of Corporal Daniel Groves, a Colorado State Patrol officer who was hit and killed by a auto as he helped another driver who had slid off Interstate 76 near Denver. A tornado also touched down Thursday in western Kentucky, damaging utility lines and trees. No deaths or injuries have been reported as yet.
Air rushed into the low-pressure area and then rose into the atmosphere. Groves had gotten out of his patrol auto to check on another vehicle that had slid off the road, police said.
Although the term "bomb cyclone" dates back to the year of 1980, it has only been used recently by meteorologists.
The storm gained "bomb cyclogenesis" or "bombogenesis" status earlier in the week after its air pressure dropped precipitously within 24 hours, causing wind gusts of almost 100 mph while simultaneously dropping several inches of snow and rain.