The sound of jingle bells filling the air will briefly give way to the growl of an odd clap of thunder across southern Ontario as an uncommon bout of thunderstorms moves through the region on Saturday evening.
A low-pressure system moving through the Great Lakes pulled some unstable air into the region, giving rise to isolated thunderstorms embedded in showers over southern Ontario.
Beyond this system, we’re looking at cold air wrapping around a major storm that’ll just miss the province to the east. These northwesterly winds will spark lake-effect snow in time for the Monday commutes.
Visit our Complete Guide to Winter for an in-depth look at the Winter Forecast, tips to plan for it and much more!
Rare bout of nighttime thunderstorms possible
Saturday was an unusually warm day across southern Ontario as winds blew moist and mild air across the border. While daytime highs poked into the mid-teens for some areas, the day’s readings fell far short from setting monthly high-temperature records.
This warmer airmass, combined with the lift of a strong jet stream zooming high above the region, will combine to foster a risk for thunderstorms across southern Ontario into Saturday evening.
We already saw some rumbles of thunder in the far southwest earlier Saturday afternoon. One storm that rolled over Sarnia produced gusty winds and pea-size hail just over the border in Michigan.
Even though we’ll miss the bulk of the action here in Ontario, we’ll still feel that storm’s influence in the cold air wrapping into the region on northwesterly winds.
Lake-effect snow squalls are likely to develop over the snowbelts southeast of Lake Huron and Georgian Bay. These squalls could pack wind gusts of 40-50 km/h, leading to severely reduced visibility at times.
Plan ahead for snow-covered roads and dangerous visibility if you’re travelling through areas expecting lake-effect snow on Monday.
As with the last snow squall event, there will be a risk for a couple bursts of snow across the Greater Toronto Area (GTA), but the region is still tapping its foot in anticipation of the first major snowfall of the year.
Going somewhere? Check out the current highway conditions before heading out!
Stay with The Weather Network for all the latest on conditions across Ontario.
WATCH: 3 things to know this weekend about Ontario’s high-impact weather