With emergency crews rescuing motorists stranded on a snow-covered highway near Sarnia, Ont., we’re hearing the term “lake-effect storm” over and over again.
But what exactly does it mean?
We see lake-effect snow when cold winds sweep across large bodies of warmer lake water, picking up moisture that freezes and is then deposited on the shore as snow.
Unlike a standard snow storm, a lake-effect storm is not a low-pressure system. Also, in a standard storm, snow falls on and off for a few hours or even a few days. In a lake-effect storm, snow falls continuously for up to 48 hours in a specific area.
This effect is enhanced when the moving air mass moves up and across higher elevations on shore. The upward movement often creates bands of precipitation that result in very heavy snowfall.
If the air temperature is too low, the precipitation is rain, not snow, and is referred to as lake-effect rain.
Areas that get a lot of lake-effect snow are called snowbelts – and there are many of them around the Great Lakes, including southwestern and central Ontario.
Lake-effect storms are quite common in that region because the area is surrounded by water on three sides.
Total snowfall around Lake Superior, Lake Huron and Georgian Bay can reach four meters every winter.
From Port Stanley in the west to Niagara-on-the-Lake in the east, from Brantford in the north to Fort Erie in the south, people often endure whiteouts that reduce visibility on the highways to zero.
Lake-effect storms aren’t common in Toronto or Hamilton because winds don’t often sweep north or west from Lake Ontario. But Toronto sometimes gets lake-effect snow from Georgian Bay.
When the wind sweeps south form Lake Huron, London and Sarnia get walloped.
These storms wreak havoc in many people’s lives, none more than meteorologists.
“My workload increases quite a bit during large snow storms,” says Global News meteorologist Anthony Farnell. “Often times I’m asked to do special coverage on the web along with live updates on television in between newscasts.
“I also help out Global National with a small weather segment in their 5:30 p.m. newscast. Preparing an accurate forecast during major storms becomes much more important, and I spend extra time looking over the forecast models and radars to predict exactly [which areas] will see the most snow.”
Though residents of Ontario’s snowbelt have endured many lake-effect storms over the years, but the memory of one in particular still makes the shudder.
During the three-day period in December 1977, lake-effect snow squalls, driven by 100 km per hour winds, dropped over 100 cm of snow on London and surrounding areas.
Farnell says the worst storm he has ever covered was on a Friday the 13th in 2006.
“I had just started at Global Toronto and, at 3 a.m., I left for Fort Erie and Buffalo, which was getting an historic lake-effect snow storm,” recalls Farnell.
“Transformers were exploding in the distance and the sky was filled with green flashes. Because it was so early in the season, leaves were still on the trees and this made the tree damage much worse.
“I did the morning show from there and worked the entire day right through to the 11p.m. news.”
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