Southern Ontario: Snow Squall Outlook for Monday, December 6 to Tuesday, December 7, 2021
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Forecast Discussion
After a brief warm-up during the early part of Monday, a cold front will sweep across the region during the afternoon and evening hours which will usher in colder air. This colder air will help restart the lake effect snow machine throughout the typical snowbelt around Lake Huron and Georgian Bay starting late Monday evening. The primary targets of these snow squalls will be the Bruce Penisula through Simcoe County and into parts of Kawartha Lakes.
Current indications suggest a fairly intense squall will set up from just north of Wiarton and come inland across Georgian Bay between Orillia and Barrie and could remain nearly stationary overnight and into Tuesday morning for over 12 hours. This band could stretch quite far inland making it as far east as Peterborough at times. Snow squall activity will continue throughout the day on Tuesday with an additional 5-15cm of snowfall accumulation expected. However, it will likely become a lot less organized as we go throughout the day so the majority of the accumulation will come Monday night into Tuesday morning. The snow squalls will drift northward towards the Parry Sound/Huntsville area late Tuesday as the wind direction shifts to a more southwesterly flow.
With hourly snowfall rates approaching 3-6cm, it will pile up quite quickly and wouldn’t be surprised to see a few locations come near 30-40cm by the end of Tuesday. There is even the potential for very localized totals up to 50cm as some models have shown, but this seems a little overdone in the model data. More general snowfall totals will range from 15-30cm throughout the region. Keep in mind that just because you’re in the heaviest accumulation zone doesn’t mean you will get it as snow squalls are a very localized event. We’ve tried our best to narrow it down as much as possible, but just a slight shift in the wind direction can dramatically change who sees 40cm and 0cm from this squall event. Travel conditions will likely be very hazardous throughout the affected region. If you can, avoid travel until later in the day on Tuesday when conditions will improve somewhat.
