Another Icy Day Ahead for Eastern Ontario; Second Round of Prolonged Freezing Rain on Friday Morning

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After being coated in ice all day Wednesday, Eastern Ontario is bracing for another round of freezing rain on Friday. This upcoming bout of freezing rain is expected to impact many of the same areas that were heavily affected by Wednesday's icing event.

A system moving into Southern Ontario late Thursday will bring mostly rain to Southwestern Ontario and the Golden Horseshoe region.

However, this system will run into the cold air lingering over Eastern Ontario, which was responsible for Wednesday's significant freezing rain. This will lead to the development of more freezing rain, starting early Friday morning along the Dundalk Highlands and extending eastward into the Ottawa Valley.

Freezing rain is forecast to continue across Eastern Ontario throughout the morning and into the afternoon. By late Friday afternoon, we could see an additional 5-10mm of ice accumulation. Considering the existing layer of ice from the previous event, this additional freezing rain poses an increased risk of power outages and hazardous road conditions.

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Regarding ice accumulation, it's important to note that the amounts mentioned are general estimates of freezing rain from the sky. Actual ice accumulation on surfaces will vary depending on the surface type, and local dynamics are difficult to predict in a broad-scale forecast.

The heaviest icing is anticipated around Bancroft, Perth, Ottawa, and Cornwall, with around 5-10mm of ice accumulation possible. It's important to note that some models predict a changeover to regular rain by late morning, particularly in the southern regions, which could limit total ice accumulation.

Elsewhere in Eastern Ontario, ice accretion of 2 to 5mm is expected before transitioning to rain. While the Kingston area was severely impacted by the last event, temperatures are forecast to rise above freezing quickly enough to prevent significant icing along the Lake Ontario shoreline.

Additionally, higher elevations northwest of the Greater Toronto Area, including Orangeville and Shelburne, may experience a few millimetres of ice as the cold air persists for a longer duration.

In Central Ontario, including Muskoka, Simcoe County, and northern parts of the Greater Toronto Area, some freezing drizzle is possible, but less than 2mm of ice accumulation is expected, as the conditions should quickly change over to rain.

Also notable is that parts of Southwestern Ontario could pick up around 15-30mm of rain during the overnight and into Friday morning. The rest of Southern Ontario not seeing the freezing rain can expect 10-20mm of rain, locally up to 25mm. All precipitation will come to an end by the dinner hour.

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Significant Freezing Rain Threat for Eastern Ontario Including Ottawa & Kingston on Wednesday

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An approaching system is set to move across Southern Ontario later on Wednesday, leading to a prolonged risk of freezing rain in much of Eastern Ontario. This system will bring warmer air, resulting in foggy and rainy conditions throughout Southwestern Ontario and the Golden Horseshoe area.

As the system advances northeast, it will encounter temperatures below freezing at the surface in Eastern and Central Ontario. The warm air will overtake the colder air aloft, creating ideal conditions for freezing rain.

Current forecasts indicate that the risk of freezing rain could last between 6 to 12 hours in parts of Eastern Ontario, beginning Wednesday afternoon and continuing through the evening into the early hours of Thursday.

In the hardest-hit regions, significant icing is possible, with more than 10mm of accumulation expected by early Thursday morning. This is likely to lead to icy road conditions and potential power outages as ice builds up on tree branches and power lines.

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Through the morning hours, drizzle and fog have already been affecting Southwestern Ontario and the Greater Toronto Area. This precipitation is expected to spread northward in the afternoon, meeting the colder air and forming a band of freezing rain from Lake Simcoe eastward through Peterborough to Kingston by mid-afternoon.

This freezing rain will persist, causing steady icing throughout the afternoon and evening. However, there is some disagreement among the models about how long the below-freezing temperatures will last. Some models suggest a gradual warm-up by evening in areas around Lake Simcoe and the Lake Ontario shoreline, which could lessen the ice accumulation in the Muskoka, Belleville, and Kingston regions.

Other models, however, indicate that the cold air will remain firmly in place with little temperature fluctuation until Thursday morning. This scenario would result in widespread icing from this afternoon into early Thursday.

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In the Ottawa Valley, especially south of Ottawa, there is more confidence in the forecast. Conditions are expected to be prime for freezing rain from late afternoon into the overnight hours. Further north, in regions like Pembroke, Renfrew, and Ottawa, ice pellets may mix in, leading to less icing but still severe impacts on travel and power.

The freezing rain is expected to taper off in the early hours of Thursday, but with temperatures remaining low in Eastern Ontario, travel conditions will still be treacherous for the Thursday morning commute. Widespread school bus cancellations are likely in this region on Thursday.

Fog will persist in Southwestern Ontario and the GTA. While it may recede slightly later on Wednesday, it's likely to return overnight in some areas.

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Regarding ice accumulation, it's important to note that the amounts mentioned are general estimates of freezing rain from the sky. Actual ice accumulation on surfaces will vary depending on the surface type, and local dynamics are difficult to predict in a broad-scale forecast.

The heaviest ice accumulation is expected between Ottawa and Kingston, with areas like Brockville, Smiths Falls, Perth, Tweed, and Bancroft potentially seeing up to 10 to 15mm of freezing rain. Other parts of Eastern Ontario, including Ottawa, Kingston, and Peterborough, are likely to experience several hours of freezing rain, with ice accumulations ranging from 5 to 10mm.

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In Central Ontario and parts of the GTA, lesser amounts of freezing rain are forecast, with around 2-5mm of ice possible for Muskoka, Kawartha Lakes, and parts of York and Durham regions. Less than 2mm is expected for Simcoe County and higher elevations northwest of the GTA. However, these areas could see higher amounts depending on how quickly temperatures rise above freezing.

Pre-Holiday Freezing Rain Risk Could Impact Travel in Ontario on Saturday

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As the countdown to Christmas Day continues, many are preparing to hit the roads this weekend for holiday celebrations. Despite expecting a warm Christmas on Monday, the lead-up promises some challenging weather.

Early Saturday morning, parts of Southern and Northern Ontario will encounter a mix of frozen precipitation, including wet snow and freezing rain.

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Southwestern Ontario, following midnight, will experience patchy drizzle originating from Michigan. In some regions, temperatures will hover just below freezing, particularly around the Greater Toronto Area and its north, west, and east.

This will allow for some of that drizzle to freeze on contact with the ground. Areas along the lakeshore of Lake Ontario may see less freezing rain, thanks to marginally warmer lake-adjacent temperatures.

The freezing rain will persist intermittently throughout Saturday morning. However, temperatures are expected to rise later in the morning south and west of Lake Simcoe. The icy conditions will extend northeast, bringing wet flurries and freezing rain to Central and Eastern Ontario late in the morning.

The most ice accumulation is anticipated from Lake Simcoe across the Kawartha Lakes to Peterborough, extending north of Kingston. This is due to an expected 6-12 hours of continuous freezing rain from Saturday morning to late afternoon.

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By Saturday evening, most areas should transition to regular rain, but northern parts of Central and Eastern Ontario might still experience freezing drizzle. The freezing rain threat could even extend overnight into early Sunday morning in the Ottawa Valley.

In Northeastern Ontario, freezing drizzle is expected throughout Saturday, subsiding by evening as temperatures rise above freezing.

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Although the overall impact of ice accretion from this event is predicted to be minimal, untreated surfaces might still develop a thin layer of ice.

The latest models concur that the most affected area will be north of Lake Ontario. This includes Orangeville, Newmarket, Lindsay, Peterborough, Tweed, and Smith’s Falls, with potential local ice accumulation up to a few millimetres—possibly 3-4mm in higher elevations.

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An expansive area encompassing the GTA, Central, and Eastern Ontario may experience minor freezing drizzle, but significant ice accumulation is not expected. Any ice formed is likely to melt quickly once temperatures rise above freezing later on Saturday.

Snowfall from this system will be minimal, with only a few wet flurries. The greatest likelihood for any snow accumulation is in Central Ontario east of Georgian Bay, but even there, it’s anticipated to be just a few centimetres.

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Lastly, minor freezing drizzle is also forecasted for Northeastern Ontario, primarily east of Lake Superior. However, significant ice accumulation is not expected in this region.

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