Biggest Snowfall of the Season Possible in Parts of Southern Ontario Including Toronto on Friday With Up to 10-20cm of Snow
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Spring may have officially started earlier this week, but the weather across Southern Ontario has been anything but spring-like. We've experienced lake-effect snow over the last few days, along with temperatures near or below the freezing mark. This marks a significant change from the pattern observed throughout the winter, especially towards the end of winter in February and early March, which saw unusually mild conditions.
Now in late March, we're tracking a potential system that could bring the most significant snowfall accumulation of the season for some regions. While this might sound daunting, it's important to remember that some areas have yet to record even 10cm of snow in a single day this season, so the bar for the 'snowiest day of the season' title is relatively low.
This system, starting Friday morning and continuing through the day into early Saturday morning, could result in widespread snowfall totals between 10 to 15cm, with possible accumulations reaching up to 20cm. This swath of heavy snow is expected to stretch from the Lake Huron shoreline through the Golden Horseshoe and into parts of Eastern Ontario along the St. Lawrence River.
The initial bands of snow are expected to move into Southwestern Ontario from Michigan during the late morning hours on Friday, spreading eastwards throughout the early afternoon. By late afternoon, the snow will cover much of the Lake Huron shoreline and extend towards the Greater Toronto Area (GTA), ranging from light to moderately heavy snowfall.
There remains some uncertainty regarding the system's track, with some models predicting the heaviest snow band stretching from Kincardine to around Lake Simcoe, while others suggest a more southern route from Grand Bend through Kitchener and into Toronto. The consensus among the models leans towards the southerly track, which we are adopting for now, but adjustments may be necessary if there are shifts in the track closer to the event.
Lake enhancement could also increase snowfall rates off the southwesterly shoreline of Lake Ontario from Toronto to Hamilton on Friday evening, extending overnight into Saturday morning. Another band of heavy snow is expected to move into the Golden Horseshoe, particularly focusing on the Niagara region just before midnight, which is when the highest snowfall rates are anticipated.
Additionally, there's a potential risk for freezing rain and mixed precipitation along the Lake Erie shoreline and in parts of Deep Southwestern Ontario, including Windsor and Chatham. Currently, the threat of freezing rain seems minimal, but it could change, with some models suggesting more prolonged icing along the shoreline.
The system will progress into Eastern Ontario just after dinner on Friday, with the heaviest snow expected to concentrate along the Hwy 401 corridor from Belleville to Cornwall, persisting into the early hours of Saturday with the most challenging conditions occurring overnight.
Snowfall is expected to taper off from west to east, concluding in Eastern Ontario by early Saturday afternoon.
Based on the current data, snowfall totals are anticipated to range from 10 to 15cm in the hardest-hit regions, including Goderich, Kitchener, Guelph, Hamilton, Toronto, Niagara Falls, Kingston, Brockville, and Cornwall.
Certain areas within this zone could see up to 20cm due to lake enhancement off Lake Ontario, hence the forecast range of 10 to 20cm on our map. If confidence in lake enhancement increases with later model runs, we may need to adjust the forecast up to 15-25cm for parts of the Western GTA.
DATA and chart FROM WEATHERSTATS.CA
With Toronto expected to receive at least 10cm of snow, this event has the potential to be the snowiest day of the winter thus far, which is quite surprising given that it's already late March. The highest daily snowfall total recorded at Toronto Pearson Airport this winter was 6.4cm on February 15th.
Although Southern Ontario has seen several snowmakers this winter, especially in the snowbelt, the Toronto area has largely been spared, with temperatures along the Lake Ontario shoreline quickly transitioning any snow to mixed precipitation.
We do not anticipate mixed precipitation being a factor for the Toronto area with this system, as temperatures are expected to remain below the freezing mark throughout the event.
Lower snowfall totals are expected to the north, with the Barrie, Orillia, Peterborough, Bancroft, and Ottawa areas likely to see between 5 to 10cm of snow. The same is true for Southwestern Ontario, from Sarnia to London, where totals are unlikely to exceed 10cm.
Less than 5cm of snow is expected in northern Central Ontario, including Muskoka, due to the moisture from the system dropping off and along the Lake Erie shoreline, where mixed precipitation could result in lower snowfall totals.
