What is the ‘Arctic blast’ deep-freezing the US and Canada?

Recent temperatures of minus 78 degrees Celsius (-108 degrees Fahrenheit) are reportedly the lowest ever recorded in the United States.

A dangerous combination of record-setting cold temperatures and powerful winds buffeted the northeastern United States and Canada over the weekend, creating life-threatening conditions and wind-chills from the Arctic blast.

New Hampshire’s Mount Washington overnight on Saturday recorded a wind-chill – a measure of how the combined effect of air and wind feels to the skin – of minus 78 Celsius (-108 degrees Fahrenheit), which appeared to be the lowest ever in the United States.

The air temperature at the peak reached -44C (-47F) with winds gusting near 160 kilometres per hour (100 miles per hour), according to the Mount Washington Observatory.

What is an Arctic blast?

The bitter weather all started farther north as frigid air collected over the snow-covered ground in the Arctic. Then the jet stream — wobbling air currents in the middle and upper parts of the atmosphere — began pushing this cold pool down into Canada and the US.

An Arctic blast is defined by the US National Weather Service as 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”.

As this Arctic air is pushed into the warmer, moister air ahead of it, the system can quickly develop into serious weather — including what’s known as a “bomb cyclone” – a fast-developing storm in which atmospheric pressure falls quickly over 24 hours.

These severe weather events usually form over bodies of water, which have lots of warmth and moisture to feed the storm.

The Arctic air reached the region just as a rapid cyclogenesis developed over Labrador and Newfoundland, churning up powerful winds. A cyclogenesis refers to an intensification of a cyclone or low-pressure storm system.

Homeless people
Homeless people stay warm at South Station, set up as warming centre, in Boston, Massachusetts, the US [Joseph Prezioso/AFP]

Which areas were affected?

Wind and extreme cold warnings were in place across large sections of Atlantic Canada – including Nova Scotia, New Brunswick, Newfoundland and Labrador – and the major cities of Montreal and Toronto were also under extreme cold advisories, according to Environment Canada.

The Arctic blast flowing into the US from eastern Canada brought record lows to Albany, New York; Augusta, Maine; Rochester, New York; and Worcester, Massachusetts, among other places.

In Caribou, Maine, there were reports of “frostquakes” – tremors that feel like earthquakes but are caused by the soil cracking suddenly in the cold – as well as trees splitting open, likely caused by sap freezing inside the trunks.

In Boston, where officials closed down the public school system on Friday, the low temperature hit -23C (-10F), shattering the day’s record set more than a century ago. In Providence, Rhode Island, the mercury dropped to -23C (-9F), well below the previous all-time low of -19C (-2F), set in 1918.

People walk over the Brooklyn Bridge
The northeastern US and Canada are experiencing an Arctic blast that could see some areas record their lowest-ever wind-chill temperatures [File: Yuki Iwamura/AFP]

What measures have been taken?

Several cities took emergency measures to aid residents, including opening warming centres and conducting outreach to ensure homeless people were sheltered from the brutal cold.

In Boston, Pine Street Inn, the largest provider of homeless services in New England, doubled the number of vans canvassing the city’s streets on Friday and Saturday, said Barbara Trevisan, a spokeswoman.

“They started going out early this week to warn people that the weather was going to be very extreme,” she said. “The goal last night was just to keep people alive and safe.”

Massachusetts Governor Maura Healey ordered South Station, the city’s main rail terminal, to remain open overnight to serve as an emergency shelter. About 50 to 60 homeless people stayed in the station overnight, Trevisan estimated.

Among them was Paul Butler, 45, who has been homeless since he was evicted in December 2021. “This is the coldest I ever, ever remember, and I worked the door at a bunch of clubs for 15 years,” said the former US Marine, who carried two bags with extra clothes and blankets.

Source: News Agencies