Snow Squalls Could Bring a Frightening 15-25cm of Snow to Parts of Southern Ontario on Halloween Night
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Many across Southern Ontario received a chilling surprise this morning: a blanket of snow. Notably, areas around Lake Huron and Georgian Bay saw accumulations thanks to the active lake effect snow from the past 24 hours.
However, Mother Nature isn’t done playing her snowy tricks, as snow squalls are predicted to make a comeback later today. In fact, lake-effect snow off Georgian Bay is already affecting the Parry Sound region this afternoon.
These snow bands will persist into the evening off Georgian Bay, but a wind shift around midnight will divert this lake effect activity southward. This means a brief but intense bout of snowfall for Muskoka and Simcoe County between 10 PM and 1 AM.
If you're travelling in this area tonight, exercise caution: these squalls can dramatically reduce visibility within seconds!
Another round of lake effect snow from Lake Huron may result in heavy snowfall from Goderich through Kincardine to the Owen Sound region, primarily in the evening and early hours, shifting south after midnight.
As the night progresses, the snow activity off Georgian Bay appears to weaken, leaving some lingering flurries near Meaford and Collingwood. On the other hand, the squalls from Lake Huron may intensify before dawn on Wednesday.
Current data suggests this main band will target the southeastern shoreline of Lake Huron, especially from east of Sarnia through Lambton Shores to Grand Bend. This region may bear the brunt of the lake effect activity from late night to Wednesday morning.
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There is some uncertainty about the exact location and intensity of the lake-effect snow. It could potentially be strong leading to heavy snowfall rates lasting several hours between Sarnia and Grand Bend. Wednesday morning might pose challenging driving conditions, with a possibility of localized school bus cancellations.
By Wednesday noon, the organized lake effect snow should dissipate. Some residual flurries east of Lake Huron might linger, but no significant accumulation is anticipated.
As typical with lake effect events, the heaviest snowfall will be localized. Current model data shows a pocket between Sarnia and Lambton Shores could see up to 25cm by Wednesday afternoon.
We're forecasting 15-25cm, but it’s crucial to understand the unpredictable nature of lake-effect snow. We’re confident someone in this zone will approach 25cm, depending on the squall’s precise path. But not everyone will see that much snow and even some may see only a few centimetres as the squall will be very narrow.
For areas northeast of Georgian Bay, up to 10-20cm is expected around Parry Sound and Sundridge, mostly falling this afternoon and evening. Surrounding regions east of Lake Huron and south of Georgian Bay might see 6-12cm, depending on the location of the lake effect activity
Central Ontario regions like Muskoka and Simcoe County could receive about 4-8cm, primarily over the period of a few hours late tonight as the squalls move south.
For the rest of Southern Ontario, significant accumulation is unlikely. However, some scattered lake effect flurries tonight and early tomorrow are possible, but it won't be widespread and more likely the closer you are to Lake Huron or Georgian Bay.
