Close Call With Potential Late-Season Snowstorm for Parts of Southern Ontario; Up to 10–20cm of Accumulation With Northern Storm Track

At the beginning of the weekend, we noticed the potential for a late-season snowstorm for Southern Ontario sometime during the middle of this week which had a surprising amount of model agreement that far out. Earlier trends suggested a more northern track that would put the heaviest snowfall accumulation through Central and Northeastern Ontario. Over the last few days, we’ve continued to go over the latest data and there has been a noticeable southern shift in the expected track of this system.

This has caused the models to diverge in the potential scenarios with some models suggesting a track so far to the south that would mean much of Southern Ontario would miss the heaviest snow except for those close to the international border. On the other hand, some models have held with a more northern track which would bring the potential for widespread 12-20cm stretching from Windsor through London and into the GTA and Eastern Ontario. This would certainly be the biggest snowfall many have seen this late into the season in quite a long time if it happens.

Normally we would have a preliminary forecast out by now with the event less than 36 hours away, but the confidence in the track is so low that we don’t think it would be responsible for us to choose one scenario and put that out like it’s the expected outcome. Instead, we have decided to put together two different maps with one showing the more northern track (Scenario #1) and the other one showing the southern track (Scenario #2). We felt it was important enough to put something out given the potential significance of this event instead of waiting until the models started to converge on a track. We do expect some variance in the track and our final map will likely be a combination of both scenarios so keep in mind it’s not one or the other. These are technically the extremes of the two tracks and the actual outcome will probably be somewhere in the middle.

As for the timing of the snowfall, we expect the first bands of precipitation to reach areas around Lake Erie just after midnight Tuesday night with it continuing to spread to the northeast throughout the morning on Wednesday. For those the still need to travel for work, the morning commute on Wednesday will likely be heavily impacted due to the extensive snowfall rates during this timeframe. Please leave plenty of time to get to your destination. The majority of the snowfall will come down during the early part of Wednesday except for Eastern Ontario which will see it linger into the afternoon hours. All of the snow should come to an end by Wednesday evening.

As we’ve said, the total accumulation from this system will depend on the track with the northern track bringing the heaviest impacts to Southern Ontario. The southern track would still have an impact on our region bringing 6-12cm of snowfall accumulation from Windsor through the Niagara region and into Extreme Eastern Ontario. Refer to the two maps above for a rough idea of the potential accumulation for your location for each scenario.

We will be continuing to go over the latest data over the next day and will have our final forecast out sometime Tuesday. Check back for more!