Skip to main content

A chain link fence is coated with ice at Mount Hamilton Cemetery in Hamilton on Dec. 22, 2013.

Peter Power/The Globe and Mail

An unusual brew of meteorological factors conspired to make the weekend ice storm that swept across Southern Ontario, Quebec and the Maritimes one of the most hazardous and damaging in recent memory.

Ice storms can arise whenever warm air forms a wedge between two layers of cold air – one high up in the atmosphere and one at the surface. Precipitation that begins as snow quickly turns to rain as it falls through the warm air. Then, as the raindrops re-enter the cold, they become supercooled, dipping below the freezing point even though they remain liquid. In such a state, droplets of water freeze on contact when they touch a surface, forming an icy glaze on roads, sidewalks and everything else.

That's what typically happens, said Marie-Eve Giguere, a warning preparedness meteorologist based at the Environment Canada's Downsview office in Toronto.

Story continues below advertisement

In this case, though, two back-to-back weather systems brought large amounts of precipitation into the region between Friday and Sunday morning, while the slow movement of the combined storm allowed for ice accumulations of as much as three centimetres in some of the worst hit locations from Niagara to Kingston.

"That's what made this storm so unusual," said Ms. Giguere.

The sheer weight of accumulating ice is often enough to bring down vulnerable trees and power lines.

Ice can also short out transformers, wreaking further havoc on the power grid.

The storm unfolded along a line from northern Texas to Nova Scotia.

The line roughly defines the boundary between a mass of cold air that has lately been stationed over the Prairies and a region of much warmer air that has brought unseasonably mild temperatures to the mid-Atlantic states.

New York's Sunday high topped 20 C. As some of that warm air was drawn northward on Saturday, the conditions for a classic ice storm were realized.

Story continues below advertisement

Although the system is now moving east, conditions will continue to be treacherous as temperatures plummet behind the storm front.

"This ice is not going anywhere.

"It's staying with us." Ms. Giguere said.

Although no single weather event can be attributed to climate change, researchers have projected more rain during the winter months in southern Ontario as global temperatures continue to rise. That means there will more opportunities for the kinds of conditions that led to the weekend ice storm, or the more severe ice storm of January 1998 which saw ice accumulations in the range of 7.5 centimetres and left more than 30 people dead.

Report an error Editorial code of conduct
Tickers mentioned in this story
Unchecking box will stop auto data updates
Comments

Welcome to The Globe and Mail’s comment community. This is a space where subscribers can engage with each other and Globe staff. Non-subscribers can read and sort comments but will not be able to engage with them in any way. Click here to subscribe.

If you would like to write a letter to the editor, please forward it to letters@globeandmail.com. Readers can also interact with The Globe on Facebook and Twitter .

Welcome to The Globe and Mail’s comment community. This is a space where subscribers can engage with each other and Globe staff. Non-subscribers can read and sort comments but will not be able to engage with them in any way. Click here to subscribe.

If you would like to write a letter to the editor, please forward it to letters@globeandmail.com. Readers can also interact with The Globe on Facebook and Twitter .

Welcome to The Globe and Mail’s comment community. This is a space where subscribers can engage with each other and Globe staff.

We aim to create a safe and valuable space for discussion and debate. That means:

  • All comments will be reviewed by one or more moderators before being posted to the site. This should only take a few moments.
  • Treat others as you wish to be treated
  • Criticize ideas, not people
  • Stay on topic
  • Avoid the use of toxic and offensive language
  • Flag bad behaviour

Comments that violate our community guidelines will be removed. Commenters who repeatedly violate community guidelines may be suspended, causing them to temporarily lose their ability to engage with comments.

Read our community guidelines here

Discussion loading ...

Due to technical reasons, we have temporarily removed commenting from our articles. We hope to have this fixed soon. Thank you for your patience. If you are looking to give feedback on our new site, please send it along to feedback@globeandmail.com. If you want to write a letter to the editor, please forward to letters@globeandmail.com.
Cannabis pro newsletter