Weather tracker: the disruption of the polar vortex behind Storm Blair | US News

A frigid arctic air mass, which gathered across Canada over the past week, spread south to the United States over the weekend. After already allowing temperatures to drop as low as -40°C in northern Canada, this cold air mass combined with moisture-laden air from the Gulf of Mexico to become a major winter storm named Blair , causing disruptive winter weather across a large region of the United States.

Over the past 24 hours, Blair has brought significant snow accumulations and dangerous ice storms and freezing rain to a wide area, from the central Great Plains in the west, through the Mississippi Valley and from Ohio, and up the east coast.

Up to 2 cm of ice is expected to accumulate on surfaces, leading to power outages and tree damage. The cold Arctic air mass is then expected to continue moving south across much of the country over the coming week, reaching the Gulf Coast.

The underlying cause of Storm Blair and the intrusion of the Arctic air mass is a continuation of the disruption of the polar vortex, a huge three-dimensional ring of powerful winds typically 20 to 50 km in altitude that rotates around from the North Pole. The disruption to its usual pattern means it will move well south across the continent in the coming days, bringing cold air with it.

The powerful and active polar vortex so far this winter in the Northern Hemisphere has been the main cause of temperatures as low as -55°C in Siberia, and now the most intense part of the vortex has moved towards the North America.

In contrast, southeast Australia has suffered an intense heatwave in recent days, with an increased risk of bushfires and fire bans for a growing number of residents in the state of Victoria. . The bushfire season so far has been particularly severe. Last week, the Grampians National Park in Victoria suffered a massive fire that affected farms and homes.

Temperatures reached around 45C in parts of Victoria on Sunday, while Melbourne, the state capital, recorded 38C. Total fire bans were enforced in three districts across the state, where authorities deemed the fire danger “extreme.” Other parts of the country also suffered heatwaves, including New South Wales, Western Australia and Tasmania.

The bushfires are reminiscent of the catastrophic summer of 2019-20, when 33 people were killed in fires that devastated an area the size of Turkey.

Delhi, India, is affected by several days of heavy fog, with zero visibility conditions reported for three consecutive mornings. This led to hundreds of flight cancellations at the city’s two main airports, as well as delays and cancellations of many train services. Visibility was worst early in the morning, but Palam International Airport, southwest of the city center, recorded a nine-hour period without visibility on Saturday. Air quality is said to be “very poor” in the Indian capital.