Slick sidewalks and slushy crosswalks are the most obvious menaces after this week’s storm, but New York City officials have another warning: Watch your head.
The same wet, packable snow that made for easy snowmen and snowball fights is also clinging stubbornly to rooftops, window ledges and scaffolding across the five boroughs. As temperatures hover around or above freezing by day (it’ll be in the mid-40s Wednesday) and dip into the 20s at night, that snow can melt, shift and refreeze into slabs of ice.
“It was more of a wet character than the previous storm,” said Bill Goodman, a meteorologist with the National Weather Service. “So it was sticking better on things.”
In New York’s canyon of high-rises, where buildings stretch hundreds of feet into the sky, even a relatively small chunk of ice can pick up speed quickly.
Frank Moscatelli, a clinical professor of physics at NYU, ran the numbers for Gothamist. If a 10-pound sphere of ice about 10 centimeters in diameter were to fall, he said, “very quickly" — in about three seconds — "it would reach a terminal velocity of close to 50 or 60 mph.”
“You’re talking about being potentially hit by something 10 pounds going 50 miles an hour. Uh, not pleasant.”
And it wouldn’t have to fall far to get there.
“I would judge about 40 feet maybe,” Moscatelli said — roughly four or five stories. “Not much.”
That means even mid-rise buildings can pose a risk if ice accumulates along parapets or ledges.
The speed, Moscatelli, is also “highly determined by shape.” Something pointy will fall faster. “It’s all about plowing through the air.”
Snow covered roofs in Manhattan sit below the One World Observatory in 2018. Rooftops are once again covered in snow after this weekend's storm.
New Yorkers have seen what can happen when ice falls from buildings. In 2018, a chunk of falling ice totaled a Chevy Equinox. In 2014, frozen piles of snow slipped from the sloped surfaces of One World Trade Center, forcing the closure of the PATH entrance below. That same year, a man sued a Midtown building’s owner after he was hit by a falling piece of snow.
Moscatelli, who lives in the city, said he’s mindful when buildings rope off sections of sidewalk after storms — as one building on his block recently did.
“You could walk more toward the curb,” he suggested, for anyone who is worried.
Buildings Commissioner Ahmed Tigani said the city is now in the “snow melt” phase of storm response, which depends largely on property owners.
That includes clearing sidewalks, but also “making sure that you’re clearing icicles and snow masses from above your head … anything that can tilt down or fall on top of people.”
So far, Tigani said, complaint levels appear consistent with past heavy snowfalls.
Tigani said it’s not something the city is overly worried about, “but we are trying to make sure that people are doing the things that I just laid out so that we don't have a problem in the first place.”
Tigani encourages anybody who spots a dangerous overhang or falling ice to call 311.
As Goodman, the meteorologist, put it: “Especially in the city, you gotta be looking up and making sure nothing's coming down.”
