We are watching an increasing strength winter storm which is expected to move into Southern Ontario early Monday morning. The snowstorm is expected to continue throughout the day on Monday with increasing range. Lake enhancement from Lake Ontario, Lake Huron and Georgian Bay is expected. Into the night (Monday night), the flood of cold air into the province will lead to increased snowfall ratios between 12-16:1 (12-16 inches of snow for 1 inch of liquid).
Following the system, strong snow squalls are likely off of Lake Ontario and Georgian Bay producing snowfall totals between 30 and 50cm, by Tuesday afternoon. Throughout the day on Tuesday, the winds will shift direction and impact areas east and southeast of Lake Huron and southeast of Georgian Bay. More information on this squall direction change including snowfall totals will be posted.
Areas in pink and marked with a '6' can expect snowfall totals between 25 and 50cm. This extends south of Lake Huron where system snow (5-15cm) and lake enhancement/snow squalls (20-40cm) will produce significant snowfall totals. This region includes Port Franks, Kettle Point, Forest, Warwick, and Warwick. Hazardous travel conditions are expected with road closures possible, especially along Highway 402 and Highway 21. Local snowfall totals in this region could reach as high as 60-65cm depending on how long the squall remains stationary and the system pulls away. Depending on the exact location of the snow squall, this region may shift up to 20 kilometres to the west.
Areas in red and marked with a '5' can expect snowfall totals between 20 and 40cm. This extends south of Lake Huron where system snow (5-15cm) and lake enhancement/snow squalls (15-25cm) will produce significant snowfall totals. This region includes Grand Bend extending inland to Parkhill, Adelaide, Watford, Wyoming, and Brights Grove. Hazardous travel conditions are expected with road closures possible, especially along Highway 402 and Highway 81. Areas such as Watford and Wyoming are just on the border of the pink (6) and red (5) regions. Snowfall totals in these areas may be in between the scale in the range of 30-40cm with locally higher and lower totals. This is due to the unknown nature of snow squalls and the length of time they will sit over a region as well as how far inland they will reach. Depending on the exact location of the snow squall, this region may shift up to 20 kilometres to the west. Another area in the red region includes much of the Niagara Peninsula. In this region, lake enhancement from Lake Ontario (10-20cm) is likely alongside the system snow (10-20cm). This region extends from the New York border near Niagara Falls and Niagara-on-the-Lake extending into St. Catharines, Grimsby, Smithville, Mount Hope, and Eastern Hamilton. Snowfall totals will be greatest between Mount Hope through to Vineland, including Beamsville due to the nature of these areas sitting just inland from Lake Ontario. Hazardous travel conditions are likely on the QEW and Highway 8/81.
Areas in orange and marked with a '4' can expect snowfall totals between 15 and 30cm. This includes multiple different areas in the region. The first region is south of Lake Huron where lake-effect snow will combine with system snow to produce snowfall totals between 15 and 20cm, locally 25cm. This includes Sarnia, Newbury, and Strathroy. The next region is south of Georgian Bay. This region can expect lake enhancement off of Georgian Bay alongside system snow. Snowfall totals between 20 and 30cm are likely with local readings between 30 and 40cm being possible, although overall unlikely. This region includes areas just south of Meaford and Collingwood such as Walters Falls, Singhampton, and Mansfield. In Eastern Ontario, a pocket of 15-25cm is likely along the New York-Quebec-Ontario borders extending from Alexandria and Lancaster to the west towards Maxville, Cornwall, Prescott, and Brockville. Travel will likely be impacted along Highway 401. Finally, areas around Lake Ontario can expect between 15 and 20cm with amounts up to 25cm being possible. This extends along Highway 401 from Kingston over to Belleville, Cobourg, Oshawa, Toronto, Mississauga, Oakville, and Burlington. This also includes all of Prince Edward County and areas along the shores of Lake Erie near Fort Erie, Dunnville, and Port Dover. Local amounts of 25 and even 30cm are possible towards Hamilton extending inland towards Millgrove and Waterdown as well as Caledonia.
Areas in yellow and marked with a '3' can expect snowfall totals between 10 and 20cm. This includes much of Southern Ontario. In Eastern Ontario near Ottawa, Perth, Sharbot Lake, Renfrew, Tamworth, Madoc, and Hawkesbury, snowfall total between 10 and 15cm is likely. Further west to include Peterborough, Lindsay, Newmarket, and Vaughan can expect snowfall totals between 12 to 17cm. Towards the extreme south near Windsor, Chatham, London and Woodstock, snowfall totals between 10 and 15cm are likely. In Southwestern Ontario including Owen Sound, Wingham, Kitchener, Barrie, Orangeville, and Markdale, snowfall totals between 10 and 15cm are likely. Isolated pockets of 15 to 20cm are possible, especially near the Dundalk Highlands towards Orangeville and Guelph. Along the shores of Lake Huron including Goderich, Amberley, Kincardine, Tiverton, Saugeen Shores and Bayfield, snowfall totals may be reduced due to Lake Huron having above zero temperatures. Snowfall totals could be reduced to 6-12cm.
Areas in green and marked with a '2' can expect snowfall totals between 5 and 10cm. This includes Tobermory and Lion's Head extending towards Midland and Orillia as well as portions of Eastern Ontario such as Apsley, Bancroft, Pembroke and Deep River.
Areas in blue and marked with a '1' can expect snowfall totals less than 5cm. This includes Algonquin Park, Parry Sound, Haliburton, and Manitoulin Island. Areas in Northeastern Ontario such as Espanola, Sudbury, North Bay, and Britt are likely to see 0-2cm of snow.
Widespread weather alerts have been issued by Environment Canada for this system. We will be monitoring this complete system and will update as needed.
Throughout this event, snow days are likely across multiple school days. We will have snow day forecasts and school closures posted each evening/morning on our website found here: https://www.weatherwatcher.space/oww-weather-day
As snow squalls and lake-enhancement develop, road closures are possible and likely, especially for areas around Lake Huron during this event. These can be found on our website here: https://www.weatherwatcher.space/oww-road-closures
In case you missed it, we published a forecast for the significant snowfall around Lake Nipigon from those snow squalls to begin the work week. This forecast can be found here: https://www.weatherwatcher.space/post/long-duration-snow-squall-event-around-lake-nipigon-to-start-the-work-week
Finally, we will have an updated forecast for the snow squalls east Lake Huron and southeast of Lake Huron and Georgian Bay later in the day on Monday or in the day on Tuesday.