April 10 (Reuters) - Blizzards and windstorms will punish the US Plains and Midwest on Wednesday and into Thursday as a powerful storm threatens more flooding in areas such as South Dakota's Pine Ridge Indian Reservation and farms along the Missouri River.
High spring temperatures will give way to heavy snow, gale-force winds and life-threatening conditions across a swath of the central United States running from the Rockies to the Great Lakes, according to the National Weather Service (NWS).
Pueblo, Colorado, hit 85 degrees Fahrenheit (30 Celsius) on Tuesday, but will drop down to 25F (minus 4C) by early Thursday. Similar temperatures are forecast in Denver.
"This is potentially a life-threatening storm," Patrick Burke, a meteorologist with the NWS's Weather Prediction Center in Maryland, said early on Wednesday.
The storm is expected to bring blinding, heavy wet snow across the region, likely downing trees and causing widespread power outages, widespread road closures and making driving treacherous, Burke said.
"It's slow moving. It won't push farther east until Friday," he said.
The storm has already sparked flood evacuations in Oregon and caused flooding in Washington state.
Some areas of western Minnesota and southeast South Dakota were expected to get up to 30 inches of wet, heavy snow, the NWS said.
The same central US area was hit by a "bomb cyclone" less than a month ago that brought deadly flooding and blizzards that closed roads and paralyzed transportation.
The whiplash in temperatures, from a high in some cities on Tuesday to freezing conditions on Wednesday, was expected to supercharge the storm with cold air.
That was the case on March 13 when a sudden drop in air pressure turned a potent storm into a so-called bomb cyclone.
Areas such as the Pine Ridge Reservation and northwest Missouri's Holt County are still recovering from last month's flooding which caused billions of dollars in damage.
Flooding was not expected to be as bad in Nebraska this time as the ground had thawed and could absorb more water.
Still, the coming storm was expected to exacerbate flooding along the Missouri River in areas where dozens of levees were breached in March, exposing communities to future surges. The river was not expected to crest in areas of Nebraska, Iowa and Missouri until between three to five days after the storm.The storm is expected to weaken and push off into the Great Lakes area and northern Michigan on Friday, bringing more rain and snow, the weather service said.