As people across the country prepare for holiday travel, dangerous wind gusts and heavy snow will produce hazardous conditions and potential infrastructure impacts from the Northwest to the North-Central U.S,the National Weather Service said Wednesday.
Meanwhile, eight million people remain under flood watches in swaths of the northwestern U.S. on Wednesday, as 31 million people are under strong wind alerts in states across more than half the country.
"Powerful winds combined with periods of snow across the Northern Plains are likely to produce whiteout conditions tonight into Thursday," the National Weather Service said.
Snow squalls across the Northern High Plains could cause rapid visibility reductions on Wednesday night.
"This will cause extremely hazardous travel," the NWS said.
Rounds of heavy snow are also expected in the higher terrains of the Cascades and Northern Rockies on Wednesday. The National Weather Service said that "additional power outages and tree damage are possible Thursday and Friday due to a combination of heavy, wet snow causing added strain on trees and power lines."
For the 31 million people under wind alerts stretching from the Pacific Northwest, across the Rockies, into the Plains and parts of the Midwest, widespread damaging winds could cause numerous power outages and more dangerous travel conditions.
Across Colorado, the strong winds combined with low relative humidity will lead to a high fire danger, including along the I-25 corridor. Wind gusts of 60-80 mph, with isolated gusts up to 90 mph in the mountains, will begin early Wednesday afternoon and last into the evening.
Boulder, Colorado, will see peak wind gusts of 80 mph, with Denver potentially reaching 48 mph. Bismarck, North Dakota, is forecast to see peak winds up to 61 mph and Spokane, Washington, is forecast to see winds of 50 mph. Reno, Nevada, will see peak wind gusts of 43 mph.
Flood watches are in effect for parts of western Washington, Oregon, and northern Idaho and Montana on Wednesday.
"Rain at the surface and lower elevations of the Pacific Northwest mountain ranges will intensify over the coming days and exacerbate flooding of rivers, creeks and streams through Friday afternoon, at least," the NWS said.
The flood watches will remain in effect through early Saturday due to the elevated risk for flash flooding and landslides.
Western Washington state has seena deluge this month of "historic" floodingthat prompted officials to askabout 100,000 people to evacuate last week,forced dozens of rescues and caused widespread destruction of roads and other infrastructure.
Another storm will bring heavy rain, drenching Northern California, arriving early Thursday morning and lasting through Friday. This storm will bring an additional 2-8 inches of rainfall, with locally higher amounts possible.
With rivers remaining high and soils saturated, the risk for more levee breaches continues over the next several days.