The arctic blast that brought record low temperatures across the United States in the past few days appeared to be easing on Thursday as air travel conditions improved and wide sections were forecast to warm up.
The National Weather Service said “a much anticipated warm up” was expected over the eastern two-thirds of the United States which had shivered through a week of record-breaking cold and two massive snowstorms.
Carriers cancelled more than 1,100 flights on Wednesday, according to FlightAware.com, down from 3,200 on Tuesday. Since January 1, carriers have cancelled more than 19,300 flights, FlightAware showed.
Record cold temperatures in the United States in recent days had disabled equipment used to fuel airplanes and posed hazards for airline ramp workers. Experts at Accuweather.com forecast warmer weather around much of the country as an arctic air blast eases in the second half of this week.
"It's looking really good today," JetBlue spokesman Anders Lindstrom said in an email. "Operations are back to being close to fully 100% operable."
But weather officials warned many areas would remain below freezing despite the warm-up. The weather service predicts temperatures will be 15 to 25 Fahrenheit below average in parts of the upper Midwest. Every US state except sunny Florida and tropical Hawaii were forecast to dip below freezing either during the day or overnight on Thursday.
The slight warming comes after some truly stunning temperatures — in some cases lower than the surface of Mars. Chicago was colder than the South Pole when officials at the Lincoln Park zoo decided to keep Anana the polar bear inside on Monday. Unlike her wild cousins she hadn't built up the protective fat stores to insulate herself against the chill.
The most dangerous cold — cold that can cause frostbite in minutes and death in a matter of hours — hit the Midwest, as a weather phenomenon called the 'polar vortex' brought frigid air from the Arctic.
At least 21 deaths were reported across the US since Sunday due to the extreme cold, including several people who collapsed while shovelling snow and others, including a one-year-old boy in Missouri, killed in vehicle accidents.
Schools, businesses and government offices were closed. Water mains and household pipes froze. Airplanes were grounded, trains were halted and roads and sidewalks became ice rinks. The National Guard was called in to help rescue hundreds of stranded motorists.
Then there was the wind chill: a calculation that represents how much colder it feels when the blinding gusts hit you in the face. That dipped as low as -52 Celsius (-61 Fahrenheit) in Montana and was in the -40 to -50 Celsius (-40 to -58 Fahrenheit) range in parts of Illinois, Indiana, Iowa, Maryland, Michigan, Minnesota, Nebraska, North Dakota, Ohio, Pennsylvania, South Dakota, Virginia, West Virginia and Wisconsin on Monday and Tuesday.
That's cold enough to toss a cup of boiling water into the air and watch it turn into snow before it hits the ground. The Mars Rover has been sending back daily temperature readings from its tour of the Red Planet ranging from -25 to -31 degrees Celsius (-13 and -24 degrees Fahrenheit).