Winter Storm Takes Aim at Parts of Southern & Northern Ontario With Up to 15–25cm of Snow & Freezing Rain Between Sunday and Monday
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A tricky system is set to bring a wide range of wintery precipitation to Southern Ontario starting Sunday afternoon and lasting into Monday. The exact impacts from this winter storm will vary greatly depending on your location so while some will need their snow shovels, others will just need an umbrella. We’re looking at accumulating snowfall with as much as 15-25cm possible in parts of Central/Eastern Ontario and stretching up into much of Northern Ontario. Further south, the story will be a few hours of ice pellets and freezing rain during the late part of Sunday then switching over to regular rain by Monday morning. In some areas, this freezing rain could lead to a thin layer of ice accretion and lead to icy road conditions, but at this point, we don’t expect anything significantly impactful. Those in Southwestern Ontario and around the Golden Horseshoe will come out of the ‘storm’ with barely anything but some heavy rainfall.
TIMELINE FOR SOUTHWESTERN ONTARIO & GTHA
TIMELINE FOR EASTERN & CENTRAL ONTARIO
The storm will begin to affect our region sometime during the afternoon on Sunday as an initial band of precipitation slides across Southern Ontario. It looks like most areas will still be near the freezing mark at this time so it will likely come down in the form of light snow. This is only the start of the system as the main wave of precipitation enters the province from Michigan a few hours later. It will be mainly in the form of rain for the Windsor and Sarnia area, but the system will encounter some colder air further north through Grey-Bruce and east of Lake Huron so here we will see a messy mix of precipitation ranging from snow to freezing rain.
The heavier precipitation will continue to the northeast with heavy snow encompassing most areas around Georgian Bay during the dinner hour and into the evening. For areas to the south, we will begin to see a slow transition over to rain although this will take a few hours. And there might be some sleet and freezing rain that mixes in during this transition period late Sunday into early Monday morning. Higher elevations that include the Dundalk Highlands (Orangeville, Shelburne etc.) into the Kitchener-Waterloo area could see some more sustained freezing rain during the evening hours. Those south of Lake Simcoe should have switched over to rain around midnight while the mixing line will slowly continue northward.
For Eastern Ontario, the precipitation won’t reach that area until the evening with snow to start and the risk of a few hours of freezing rain during the overnight particularly through the Ottawa Valley and Bancroft area. The Kingston and Brockville region will escape the worse with a faster transition over to rain just after midnight which will limit any impact from snow or freezing rain. All areas through Eastern Ontario will have transitioned over to rain by mid-morning, but a slick morning commute is still expected due to the previous snow and freezing rain combined with more moisture.
Conditions for all areas of Southern Ontario will begin to improve later in the morning on Monday as warmer air causes a brief rise in temperature for at least the early part of Monday. The cold air will return later in the day which may pose a flash freeze risk depending on how fast the temperature drop occurs.
Refer to the timeline graphics above for more specific details on timing and impact for your region.
In terms of snowfall accumulation, the heaviest snowfall totals will be found in the more northern part of our region. This zone where there is the potential for 15-25cm of snowfall accumulation extends north of a line from Parry Sound through Huntsville and into the Renfrew area. Just to the south, there is some tremendous uncertainty regarding exactly how much snowfall accumulation be expected. This includes Southern Muskoka and into the Ottawa Valley where anywhere from 5-15cm of snowfall accumulation is possible. This uncertainty is due to some sleet and freezing rain mixing in which would reduce snowfall totals. However, it’s unclear how fast the transition to sleet or freezing rain will happen. Lower amounts are expected to further south you go with most of the accumulation being contained to regions north of Lake Simcoe.
As we’ve mentioned, the areas with the highest risk of freezing rain will include the Dundalk Highlands and parts of the Ottawa Valley and Algonquin Park. The freezing rain will be highly elevation-dependent so it should be mostly contained to these areas where it could be noticeable on untreated roads and may even accrete on surfaces to an extent. Outside of this, very limited accretion is expected as the transition will be quite quick, but could still lead to some isolated icy road conditions until the switch-over happens.
Those in Southwestern Ontario and around the Golden Horseshoe will see primarily rain with totals ranging from 10-25mm. A few localized areas may pick up over 25mm especially as it’s not out of the question that we see some non-severe thunderstorm activity in Deep Southwestern Ontario which would boost totals. Wind gusts appear less strong than earlier data indicated so we’re going with widespread gusts between 60-80km/h with the potential for gusts near 90-100km/h for those in the Niagara Region to the northeast of Lake Erie. Blowing snow may also be an issue with these strong wind gusts.
The effects of this system won’t be just felt in Southern Ontario, but Northern Ontario will be on the cold side of this storm so they’re looking at heavy snowfall. Snow will start late Sunday morning and continue throughout the day and into early Monday. Accumulation will range from 15-25cm including most of Northeastern Ontario and into the Thunder Bay region. Lower amounts are expected as you go further to the northwest where there will be less moisture. The snow will taper off by early Monday afternoon as the system moves out over Quebec.
