The National Weather Service (NWS) is predicting a storm with severe blizzard conditions and winds from 50 to 70 miles per hour.
According to the Weather Channel, the winter storm is expected to increase in strength throughout Wednesday, with heavy winds and snow continuing into Thursday.
A large swath of the USA was under a variety of warnings, advisories, and warnings.
Amid the expected severe weather, more than 1,200 flights within, into or out of the United States were canceled as of Wednesday morning, according to the website FlightAware. The majority of those cancellations were flights destined for or originating at Denver International Airport (DIA), where a blizzard warning is in effect.
"Snow and gusty winds from Ulmer continue from the Colorado Rockies to western South Dakota and much of Wyoming". Wind gusts of 50mph to 70mph are expected across Colorado, New Mexico, Oklahoma, and Texas, while some areas could see hurricane-force gusts of 100mph. It's called a "Bomb Cyclone" which is a rapid drop in pressure over 24-hours. Strong wind gusts are forecast, possibly reaching 55 miles per hour.
"It's a powerful storm system that when it starts to come together, strengthens very quickly", Accuweather meteorologist Matt Rinde told TIME. "With severe weather on the southern side, blizzard conditions on the northern side, the concern for flooding, and then, the winds that are outside of the thunderstorms. It's an impressive event from top to bottom".
Southwest Airlines cancelled 411 flights, while SkyWest Airlines, headquartered in Utah, had cancelled 259 flights by Wednesday morning. It will move through the Upper Mississippi Valley and Upper Great Lakes region on Thursday, NWS said.
In the Denver area, blowing snow could cause risky blizzard conditions.
"Southwest has proactively canceled almost all operations" out of DIA, the airline said Tuesday in a statement.
The National Weather Service warned residents of Boulder, Colo. against traveling on Wednesday afternoon and evening, citing the possibility of icy roads, whiteout conditions, and strong winds, according to CNN.
"It's better to be out of it", he says.