Classic fall storm could bring Ontario's first snowflakes
A blast of Arctic air could turn lake effect rain into a wintry mix by Friday night
Ontario is in for a classic fall storm, with heavy rain, strong winds, and a sharp drop in temperature that could bring the season's first lake-effect snowflakes to southern Ontario.
A large low pressure system is expected to sweep across nearly the entire province beginning Thursday evening, bringing wet and windy weather. Rain will fall in the Greater Toronto Area (GTA) and Ottawa overnight, continuing into early Friday.
There may also be a rumble of thunder along the Lake Erie shoreline Friday morning, adding to the unsettling start to the day. This may increase the rainfall amounts in locations where there is a thunderstorm.
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Rain gives way to a blast of cold air
Rainfall should subside by Friday, though scattered showers may persist as the storm moves away.
Behind the system, much colder air will rush south, bringing wind gusts of around 50 km/h and a rapid drop in temperatures, particularly Friday evening.
Some inland areas may experience temperatures approaching or the below freezing mark.
The strong winds could also cause higher-than-normal wave heights along the Great Lakes, resulting in rougher conditions along the shorelines.
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First flakes possible Friday night
The passage of colder air over the relatively warm Great Lakes could lead to lake-effect precipitation downwind of Lake Huron and Georgian Bay.
The temperature difference between the chilly air and the warmer lake waters can cause bands of showers. As temperatures fall, some of the precipitation may mix with snow overnight Friday.
However, it is still too early to predict whether the rain will turn to snow and how much of southern Ontario will see it.
The setup will be worth watching as the first taste of winter could arrive before the weekend.
Stay with The Weather Network for the latest across Ontario