Polar vortex returns to the country
Monday, February 24, 2014, 9:07 -
After a brief warm up, people across the country are being told to prepare for the oh so beloved return of the polar vortex this week.
"For those who are hoping for an early spring, unfortunately the news is not good," warns meteorologist Doug Gillham in his latest Insider Insight. "We are transitioning back into the pattern that we have already seen several times this winter with air masses that originate in Siberia crossing over the North Pole and tracking into central Canada."
Temperatures will significantly plummet in areas east of the Rockies throughout the week.
"Areas spanning from Calgary to Toronto will be 10 to 15°C below normal this week," says Brian Dillon, another meteorologist at The Weather Network. "Regions east of Toronto will be colder starting on Monday. However, with the lack of moisture through the Prairies and Ontario, there will be no big snow storms for the next five days."
The frigid conditions prompted the City of Toronto to issue an extreme cold weather alert Monday morning, advising homeless people to seek shelter.
This past weekend was already a cold one for the Prairies, and widespread windchill warnings were issued early Monday.
"Northwest winds of 15 to 20 km/h combined with temperatures near the minus 30 mark are creating extreme wind chill values ranging from minus 40 to minus 45," said Environment Canada in the warning.
Cold air is expected to infiltrate Ontario on Monday, while getting progressively cooler throughout the week.
Meanwhile, Atlantic Canada will see a series of lows passing offshore that will have to be monitored throughout the week.
On the contrary, British Columbia's south coast will see a much milder week after a weekend snow storm dumped close to 40 cm of snow across the region Saturday into Sunday.
LOOKING AHEAD TO MARCH
"As we head into March, there are numerous signs that we will continue to see below seasonal temperatures from the central Prairies to Atlantic Canada," Gillham adds. "To develop a long range forecast such as this, we analyze the global weather pattern and seek to anticipate changes in the pattern with the assistance of numerous long range models."
WHAT EXACTLY IS A POLAR VORTEX?
The polar vortex is by no means something new or something rare. It is a permanent atmospheric feature all year round existing at the North and South Poles. They are a circulation (on a planetary scale, not a mesoscale like a tornado, so it’s big) and are located from the middle troposphere to the stratosphere so it is an upper level phenomenon. The polar vortices are strongly reliant on large scale temperature gradients so in the winter, they are at their strongest due to the temperature gradient between the equatorial regions and the poles. The term “polar vortex” has been used in scientific papers since the 1940’s.
Here's a brilliant explanation by Weather Network meteorologist Doug Gillham about what the polar vortex is:
With files from Dayna Vettese