By Michael Hirtzer and Gina Cherelus
CHICAGO/NEW YORK (Reuters) - Bone-chilling cold that paralysed a large swath of the United States this week and caused more than a dozen deaths eased on Friday as an errant Arctic air mass retreated, setting the stage for a warmer weekend in the Midwest and the Northeast.
In Chicago, where the mercury dipped as low as minus 22 Fahrenheit (minus 30 Celsius) earlier this week, temperatures of 19F (minus 7C) on Friday morning felt positively balmy for some in the nation's third-largest city.
"Today's wonderful because it's not below zero," said Mary Crissie, 47, who said she closed her deli franchise in the Loop, Chicago's downtown financial district, on Wednesday.
"I didn't want to put my employees at risk because of the severe weather," she said. "The Loop was a ghost town."
Temperatures from southern New England to the Upper Midwest should reach the mid-40s to low 50s Fahrenheit through the weekend and Monday, forecasters said, after a record-breaking cold snap that stopped mail deliveries in some parts of the Midwest and shuttered schools and businesses.
Meteorologists linked the spell of brutal cold to the polar vortex, a reservoir of icy air that usually swirls over the North Pole. Shifting air currents caused it to slip down through Canada and into the U.S. Midwest this week.
Bryan Jackson, a National Weather Service meteorologist, said on Friday the core of the vortex was pulling back, though residual icy air was still pushing over to the U.S. Northeast.
Temperatures on Friday afternoon ranged from the single digits to teens, but above zero F in most of the Midwest and Northeast, according to the weather service.
DEATH TOLL MAY RISE
More than a dozen deaths in several states were linked to the deep freeze since Saturday, and the number was expected to climb as authorities identified more victims.
On Friday, police in East Moline, Illinois, about 160 miles (260 km) west of Chicago, said the weather may have contributed to the death of a FedEx freight driver whose body was found between two trucks on Thursday outside a company distribution hub.
"The weather is being considered by investigators as a circumstance that may have played a role in the death," East Moline Police Captain Darren Gault said in a statement on Friday. An autopsy was scheduled for next week.
A representative for FedEx did not immediately respond to a request for comment.
Cook County's medical examiner's office said there had been one confirmed cold-related death this week in the Chicago area. A trauma surgeon at the city's largest public hospital had told Reuters on Thursday there were nine cold-related deaths in the city.
Asked about the discrepancy, a spokeswoman for the hospital said they would defer to the medical examiner's office for a definitive tally.
More than 40 cold-temperature records were broken on Thursday, the coldest morning since the polar vortex moved in late on Tuesday. The mass of Arctic air had clung to a swath of the United States from Iowa and the Dakotas across the Great Lakes region and into Maine for days.
Amtrak restored rail service to and from Chicago on Friday, and the U.S. Postal Services resumed mail delivery in six Midwest states after suspending it for days.
(Reporting by Rich McKay in Atlanta and Gina Cherelus in New York; Additional reporting by Peter Szekely and Gabriella Borter in New York and Michael Hirtzer in Chicago; Editing by Frances Kerry and Jonathan Oatis)