The streets of the nation's largest city were met with a literal wall of winter on Wednesday when a snow squall brought blinding wintry conditions to New York City, hours after triggering a deadly pileup on an interstate in Pennsylvania.
The National Weather Service office in Upton, N.Y. issued a snow squall warning around 3:23 p.m. on Wednesday for the greater New York City area, which warned of "white out conditions" in heavy, blowing snow for a 45-minute period. The wall of white arrived in the city around 4 p.m.
"You need arctic air, and it is like a thunderstorm, except in the form of a snowstorm. It lasts very quickly - or relatively speaking - and it causes a lot of problems if you're on the roads," Dean added.
According to the National Weather Service, a snow squall is an intense short-lived burst of heavy snowfall that suddenly limits visibility and is accompanied by gusty winds.
"They may be characterized by one main squall or multiple squalls," according to the agency.
Snow squalls restrict visibility "in a matter of seconds," and severely impact travel.
"The combination of quick reductions in visibilities and sudden slick conditions on roadways can often lead to high speed wrecks, pileups, and subsequently injuries and fatalities," according to the NWS Wilmington office in Ohio. "There is also a high economic impact as interstates can be shut down for hours."
The very same scenario played out Wednesday into Thursday in central Pennsylvania, after a multi-vehicle wreck along Interstate 80 left two people dead and dozens injured.
The crash involving around 30 cars and trucks was reported at about 1 p.m. on I-80 in White Deer Township as blinding snow made the highway slick, state transportation officials said.
"It's one of those things where first you see a few snowflakes and you think, 'oh, this isn't anything' and then you see just suddenly a blanket of white," State College resident Dawn Rosenbaum told FOX56.
Visibility dropped, leading to a chain-reaction crash on the stretch of the highway between the Lock Haven and Williamsport exits.
"When we all put on our brakes, some people (drove) off the side of the road, just to not hit the other person in front of them, and then we came to a complete standstill," Rosenbaum told the television station.
Ted Vaught, who was on his way to Ohio when the crash happened, called his family "lucky."
"We just prayed that they wouldn't run into us," Vaught told FOX56. "The fellow behind us stopped well behind us but then he got run into by a tractor-trailer from behind him. Then another one."
Evangelical Community Hospital in Lewisburg reported receiving 37 patients from the crash. At least three were transferred to other facilities. Another 21 people who weren’t patients were housed at the hospital and a family center set up at a hotel.
Geisinger Medical Center said it treated nine patients, including three from other facilities, but no medical updates were immediately available.
The Union County coroner's said that one man died in the crash, and the Montour County coroner said around 11 p.m. a second person had died at a hospital. Officials told FOX56 the state of the vehicles was so bad that crews had not been able to get the man's body out, hours later.
The interstate was closed for 34 miles in both directions until eastbound lanes reopened five hours later. Westbound traffic still was being detoured Thursday morning along I-180 and Route 220 while tow trucks worked to remove the mangled cars and trucks in the wreck.
In the wake of the snow showers and snow squalls, arctic air has left the region in a deep freeze Thursday.
Temperatures in the teens and single digits were reported around much of New England, while the NWS New York office reported a "quite chilly" start to a day that will see highs reach only into the 20s with "crystal clear" skies.
The NWS's Weather Prediction Center said the cold will stay a few days before eventually moderating in time for Christmas.
"Much of New England will remain in the deep freeze as we head into the weekend," forecasters said. "In contrast, warmer than normal temperatures across the northern and central Plains are expected to expand eastward into the Great Lakes, Ohio Valley, and the Southeast by the weekend."
The Associated Press contributed to this report.