High Uncertainty With a Potential Snowmaker to Impact Southwestern Ontario on Monday
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NOTE: You can click on the map to open a zoomable image which will be easier to read.
Data from pivotal weather
Forecaster: Brennen Perry
Published: Sunday, March 5, 2023
As the clean-up continues from the impactful blizzard that brought up to 30cm to parts of Southern Ontario on Friday, we are monitoring another system that has its sights set on our region to start the week. However, there is significant disagreement among the weather models with them split into two camps on how much snow it will deliver to Southwestern Ontario.
One group of models suggests this system could bring widespread accumulating snowfall with totals near 15cm in some areas between Monday evening and Tuesday morning. On the other hand, another group of models shows the system fizzling out as it enters our region leading to a few centimetres of accumulation at most in the hardest-hit regions. Models usually have a good handle on the expected snowfall accumulation within the next 24 hours, but they are struggling with this upcoming system.
Starting with the snowier group of models including the HRRR and GFS which are American weather models. They show some light snow starting to move into Southwestern Ontario near the Lake Huron shoreline by the afternoon on Monday. By the evening, heavier precipitation will move into Deep Southwestern Ontario leading to a brief heavy blast of snow from Sarnia through London and into the Niagara region. The Windsor area should stay above the freezing mark with rain being the main precipitation type so very little snowfall accumulation is expected there. Snow will continue into the overnight and pre-dawn hours on Tuesday. Although the bulk of the accumulation will come during the evening hours on Monday making for a potentially messy evening commute.
As for the overall snowfall accumulation, if this scenario verifies then we could be looking at widespread totals ranging from 10 to 15cm in the Sarnia, London, Hamilton and Niagara regions. Accumulation will drop off quite fast to the north with locations such as Barrie and Toronto picking up a few centimetres of fresh snow by Tuesday morning.
NOTE: You can click on the map to open a zoomable image which will be easier to read.
Data from pivotal weather
The other group of models which includes the NAM (American), European and Canadian models show significantly less snow. All the models agree on the general location and afternoon snowfall. However, this group shows the heaviest bands of precipitation shifting south of our region over Ohio and Pennsylvania. As a result, snow will end by the dinner hour instead of early Tuesday morning leading to a lesser impact on the evening commute.
Total snowfall accumulation will range from 2-5cm at most with Sarnia and London seeing the highest totals. For most of Southwestern Ontario, they would only see a dusting of snow compared to the widespread 10-15cm of snow suggested by the other models.
What scenario is most likely? We would lean towards the models showing less snow as they include the more high-resolution models and is the solution favoured by a slight majority of the models. However, the snowier solution can’t be completely ruled out as several models have consistently shown it and it isn’t just one outlier. We will continue to monitor the latest data and hopefully, the models can settle on one consensus with this evening's model run and then we can put together a forecast with more confidence. Stay tuned!
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