Snowfall is Possible in a Wide Swath of Southern Ontario Beginning late Wednesday
Southern Ontario has experienced calm weather this week. Unseasonably warm weather lingered long into early November, but now temperatures are more seasonal, which is a welcome change.
Winter in Southern Ontario has been devoid of snow so far this season. Despite the earliest snowfalls in Central Ontario, Ottawa Valley, and the Dundalk Highlands, most of Southern Ontario has yet to see its first snow.
Several weather systems are expected to arrive in the coming days, bringing colder air and the potential for wet flurries by Wednesday evening.
Despite this initial blast of wintry weather, significant accumulation isn’t expected. Since the ground is already wet and relatively warm from earlier rainfall, any snow that falls will likely melt upon contact with the wet and relatively warm ground.
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The Great Lakes region will see its first flurries of the season, as a slow-moving system pulls moisture from New England.
Precipitation will be abundant, with heavy rain predicted into the weekend. Throughout Eastern Ontario, rain totals are expected to range from 25 to 50 mm.
Initially, heavy rain is expected to arrive in Deep Southwest Ontario and areas near Lake Erie by dinnertime on Wednesday.
Wind gusts of 70-80 kilometers per hour may accompany this line of precipitation. Mostly moderate gusts are expected, but isolated gusts near 90 km/h are likely over the Niagara region in the late evening.
Colder air will rush in from the west as this line of rain crosses Southwestern Ontario. The speed of temperature drop and precipitation movement is different among models. The temperatures in Southwestern Ontario might dip as low as freezing by Wednesday.
If this happens, Sarnia, London, Goderich, Kitchener, Guelph, and Orangeville might experience wet snow.
Rain earlier in the day and temperatures above freezing means any snow will melt on contact. Dundalk Highlands may have light accumulations overnight, particularly northwest of the GTA.
By Thursday morning, most moisture will spread to Lake Huron and Central and Eastern Ontario. Further moisture will be provided by a secondary system over New England, enhancing precipitation throughout Eastern Ontario.
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Eastern Ontario will see temperatures around freezing, especially southwest of Ottawa and at higher elevations, bringing the possibility of wet flurries. Further west, heavy rains will continue into the Ottawa region.
The heaviest rain will be in Eastern Ontario overnight Thursday and into Friday. Friday morning and afternoon will be mostly sunny with lingering showers in the west and central parts of the province.
Rainfall totals in Eastern Ontario, including Kingston and Ottawa, will range from 25 to 50 mm. Thunderstorm activity could bring up to 30-40 mm to isolated pockets in Southern Ontario.
By Friday morning, snow showers may persist in higher elevations near Bancroft, resulting in 2-5 cm of accumulation. Snow might stick, but temperatures are close to freezing.
Snow is on the way but not everyone is ready. Earlier models predicted lake-effect snow would trigger a significant cooldown. According to the latest data, Cooldown shouldn’t be as severe as anticipated.
It’s still possible to see lake-effect showers on Saturday, but they won’t be cold enough to snow.
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