What is the ‘Arctic blast’ that made wind chill temperatures plunge to -78C in the US?

A ‘once-in-a-generation’ cold combined with powerful winds swept the northeastern United States and Canada on weekend.The Arctic blast caused record-low temperatures and the coldest wind chill ever, with cities and states issuing emergency alerts.The wind chill in New Hampshire’s Mount Washington dropped to minus 78 degrees Celsius on Friday (3 February), the lowest ever in the United States, as per Al Jazeera.What is the Arctic blast and how did it grip northeast America? We explain.Arctic blastAccording to the US National Weather Service, an Arctic blast occurs when “very cold air masses that typically originate in the Siberian Region of Asia, cross over the North Pole into Canada and push south and east into the lower United States”.Ryan Maue, a private meteorologist in the Atlanta area, explained last December that when frigid air assembles over the snow-clad ground in the Arctic, then the jet stream – strong winds in the middle and upper parts of the atmosphere – start pressing this cold pool into Canada and the US, reported Associated Press (AP).As this Arctic air reaches warmer, moister air, it can cause severe weather conditions such as a ‘bomb cyclone’.As per National Oceanic and Atmospheric Administration, a bomb cyclone or bombogenesis is a fast-developing storm that forms when atmospheric pressure falls rapidly.Maue told AP: “These severe weather events usually form over bodies of water, which have lots of warmth and moisture to feed the storm.”Late last December, the US was hit by an Arctic cold snap, leading to extreme cold, heavy snow and intense winds across the country.ALSO READ: Which are the coldest places in the world?How the Arctic blast shivered the US and CanadaAl Jazeera reported citing Environment Canada that Nova Scotia, New Brunswick, Newfoundland and Labrador were under wind and extreme cold warnings, while extreme cold advisories were also notified for the cities of Montreal and Toronto.In the US, wind-chill warnings were issued for New York state and all six New England states – Massachusetts, Connecticut, Rhode Island, New Hampshire, Vermont and Maine in view of the “powerful” Arctic blast.[caption id="attachment_12111982" align="alignnone" width="640"] The Arctic blast gripped northeast US over the weekend. AP[/caption]The spine-chilling Arctic air reached New England just as rapid cyclogenesis formed over Labrador and Newfoundland, triggering powerful winds, meteorologist Donald Dumont at the National Weather Service (NWS) in Gray, Maine, told AP.Cyclogenesis is a development or intensification of a cyclone or low-pressure storm system.The Arctic blast flowing from eastern Canada to the US ushered record-low temperatures in Albany, New York; Augusta, Maine; Rochester, New York; and Worcester, Massachusetts, Reuters reported.

The National Weather Service bureau in Caribou, Maine, called it an “epic, generational arctic outbreak”.

Mercury in Eureka, Canada's northernmost Arctic weather station, was at minus 41 degrees Celsius on Friday morning.Boston recorded minus 14 degrees Celsius on Saturday morning.In Providence, Rhode Island, the mercury dipped to minus 23 degrees Celsius, breaking the previous all-time low of minus 19 degrees Celsius in 1918.Steps to battle cold New York City imposed a code blue weather emergency under which no homeless shelter could refuse anyone.Schools were shut in Boston and Worcester, Massachusetts, and the two largest cities in New England on Friday amid concerns about the risk of hypothermia and frostbite, reported Reuters.Many cities also took measures to protect the homeless from the brutal cold.Massachusetts governor Maura Healey allowed the South Station transit hub open overnight so that around 60 homeless people could sleep safely inside amid life-threatening conditions caused by the Arctic blast."This is the coldest I ever, ever remember, and I worked the door at a bunch of clubs for 15 years," a person taking shelter at the station told AP.Boston’s Pine Street Inn, the largest provider of homeless services in New England, increased the number of vans to transport people to shelters over the weekend.[caption id="attachment_12112002" align="alignnone" width="640"] Many US cities also took measures to protect the homeless from the brutal cold. AFP[/caption]New York’s governor, Kathy Hochul, advised residents to limit their time outdoors and take proper precautions.Frostquakes, splintering trees and moreCaribou’s NWS said it got reports of "frostquakes." "Just like earthquakes, [they] generate tremors, thundering sensations. These are caused by sudden cracks in frozen soil or underground water when it's very cold," the weather office wrote on Twitter elaborating on frostquakes.There were also reports of trees splitting open, possibly due to sap freezing inside the trunks in Caribou, as per Al Jazeera.In Southwick, Massachusetts, strong winds brought down a tree branch on a car, killing an infant.Massachusetts General Hospital said it treated several people for hypothermia and some for frostbite.“The reason people unfortunately end up with severe frostbite in most cases is just because they don’t have anywhere warm and safe to go,” Dr Ali Raja, deputy chair of the emergency department, said, as per AP.By Sunday, the mercury rose in many affected regions as the cold air departed.With inputs from agenciesRead all the Latest News, Trending News, Cricket News, Bollywood News,India News and Entertainment News here. Follow us on Facebook, Twitter and Instagram.