Wednesday, December 27, 2017 – The Polar Vortex is back and it’s delivering some of the coldest air on the planet to Ontario with dangerous windchills and another round of snow to coat the ground as we say goodbye to 2017.
With many cities across southern Ontario under extreme cold warnings on Wednesday, it may be disheartening to know that the coldest air has yet to arrive. In fact, it may be record-breaking cold by New Year’s Eve across parts of Ontario (more on this below).
As we remain locked in this cold regime, the relatively warm Great Lakes will also be in action, producing bands of lake-effect snow that vary in intensity and location, occasionally impacting areas outside the traditional snow belt regions.
Through Thursday morning, snow squalls will target areas generally southeast of Lake Huron and Georgian Bay, with the most intense snowfall occurring along Highway 21 from Goderich to Port Elgin
Watch below: What is lake-effect snow?
Fresh coating of snow
Thursday overnight into Saturday, a weak and disorganized system is forecast to slowly pass through southern Ontario, allowing for widespread light snow to break out. Most will see a minimal coating of snow heading into the weekend, but the system will take advantage of the heat and moisture supplied by the Great Lakes, with bands of lake-enhanced snow developing in response. This set up introduces quite a challenge to forecasters, as these heavier bands of snow meander and cause a few targeted areas to overachieve in snowfall amounts.
The key to nailing the location of these bands is the wind direction, but with a disorganized system, the winds also remain disorganized and it becomes harder to pinpoint where the heaviest snow will fall.
On Friday, a southeast wind may set up off Lake Ontario, which would bring the heavier band of snow into parts of the GTA through the day and leaving a higher amount of snow on the ground.
Into the New Year
A reinforcing blast of Arctic air straight from Siberia may break temperature records across Ontario, including Toronto, Ottawa and Windsor as we head into New Year’s Eve and New Year’s Day. If you have outdoor plans, be sure to bundle up as temperatures to start the first day of 2018 will be in the minus 20’s and windchills in the minus 30’s.
In addition, bands of lake-effect snow will persist much of the time across the snow belt areas with the risk for whiteout conditions for the final days of 2017 and to start the new year.
“The frigid weather will continue into the first several days of 2018, but the pattern is expected to relax as head into the second week of January,” says The Weather Network’s meteorologist Dr. Doug Gillham.