New York/Washington: A massive winter storm stretching across a 2,000-mile path from the southern Rockies to the East Coast has unleashed widespread snow, sleet and freezing rain across the United States, triggering mass flight cancellations, dangerous road conditions, and widespread power outages in at least 20 states.

More than 15,000 US commercial flights have been cancelled through Monday, with another 8,792 flights delayed, according to FlightAware. Major disruptions were reported at Dallas-Fort Worth International Airport, where more than 1,400 flights were cancelled, while Chicago O'Hare recorded over 400 delays, FOX reported.

By Saturday and Sunday alone, around 13,000 flights were called off nationwide - already marking the highest single-day cancellation levels since the coronavirus pandemic, according to aviation analytics firm Cirium.

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All Saturday flights were cancelled at Will Rogers International Airport in Oklahoma City, and Sunday morning departures were also called off as officials attempted to restart services later in the day. Near-total cancellations were reported at Ronald Reagan Washington National Airport, while disruptions piled up at airports in Chicago, Atlanta, Nashville and Charlotte.

Ice creates treacherous conditions, power outages

The storm has brought widespread heavy snow, sleet and freezing rain, threatening nearly 180 million people, more than half the US population, the National Weather Service said. Ice has created treacherous travel conditions in Arkansas and Louisiana, forcing major road closures.

Power outages reached approximately 120,000 customers, including around 50,000 each in Texas and Louisiana, according to poweroutage.us.

In Shelby County, Texas, ice-laden pine trees snapped, pulling down power lines and leaving a third of the county's 16,000 electric customers without power.

"We have hundreds of trees down and a lot of limbs in the road," Shelby County Commissioner Stevie Smith said from his pickup truck. "I've got my crew out clearing roads as fast as we can. It's a lot to deal with right now."

In DeSoto Parish, Louisiana, more than half of all electric customers lost power.

"We got limbs that are dragging the ground," said Mark Pierce, a spokesperson for the local sheriff's office. "These trees are just completely saturated with ice."

'A storm the likes of which we haven't seen in years'

Forecasters warned the storm's icy mix would continue spreading eastward through the evening, with snow, sleet and ice overspreading much of the East Coast by Sunday morning. Some northeastern areas are expected to receive more than one foot of snow.

"The snow and the ice will be very, very slow to melt and won't be going away anytime soon, and that's going to hinder any recovery efforts," said Allison Santorelli, a meteorologist with the National Weather Service.

Weather experts said the system is unusual in both size and impact.

"I think there are two parts of this storm that make it unique. One is just a broad expanse of spatial coverage of this event ... You've got 2,000 miles of country that's being impacted by the storm with snow, sleet, and freezing rain," said Josh Weiss, a meteorologist at NOAA's Weather Prediction Centre. "The other part of this storm that's really impressive is what's going to happen right afterwards. We're looking at extreme cold, record cold."

The Midwest recorded wind chills as low as minus 40°F (minus 40°C), with frostbite possible in under 10 minutes. Rhinelander, Wisconsin, saw its coldest reading in almost 30 years at minus 36°F (minus 38°C).

Emergency declarations, National Guard deployment

President Donald Trump approved emergency declarations for at least a dozen states, with more expected. FEMA pre-positioned supplies, staff and search-and-rescue teams across multiple states, according to Homeland Security Secretary Kristi Noem.

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