First "Elevated" Severe Thunderstorm Risk of 2023 Incoming to Southern Ontario (Wed, Apr 5, 2023)

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Forecaster: Brennen Perry & Adam Skinner

Published: Tuesday, April 4, 2023

A line of severe thunderstorms is possible across Southwestern Ontario on Wednesday and the risk will extend into isolated parts of Central, Niagara and the GTHA. The morning will bring heavy rain, hail and thunderstorms but the afternoon and evening will bring the strongest risk for damaging wind gusts (120km/h+), large hail (2-4cm), isolated flooding (50mm+) and frequent lightning. While the strongest risk remains stateside, the possibility of intense storms crossing continues to increase with each model run.

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We’ve also identified an isolated tornado risk for much of Southwestern Ontario, stretching into parts of the GTHA and Niagara. There is a slightly more enhanced risk in deep southwestern Ontario closer to the US border and Lake Erie as well. However, we’ve seen models suggesting the risk could be a bit more widespread and further to the north. We may upgrade this risk but for now, we feel an isolated tornado region covers the chance of isolated tornado spin-ups tomorrow.

Be sure to stay informed and monitor weather updates as this potent storm system approaches. The impact of freezing rain, heavy rainfall, and possible severe thunderstorms, combined with significant ice accretion and potential power outages, could cause some disruptions to daily routines and travel plans.

Make sure to check out our freezing rain and flood risk forecast.

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Potent Storm Brings Freezing Rain, Heavy Rainfall, and Severe Thunderstorm Risk to Southern Ontario on Wednesday

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Forecaster: Brennen Perry

Published: Tuesday, April 4, 2023

A powerful system arriving from the west is expected to deliver a variety of precipitation types and potential travel disruptions starting early Wednesday morning and lasting throughout the day in Southern Ontario. The strong storm system is expected to reach the region just after midnight, beginning around the Bruce Peninsula and Georgian Bay, before moving further eastward.

As the system encounters colder air over Central and Eastern Ontario, it will lead to the development of a widespread band of freezing rain during the morning hours. In the Ottawa Valley and Algonquin Park, precipitation may initially begin as ice pellets before transitioning to freezing rain. Heavy icing will impact regions such as Simcoe County, Muskoka, Kawartha Lakes, Haliburton, Peterborough, Bancroft, Brockville, Ottawa, Renfrew, Cornwall, and Pembroke.

Ice accretion in the hardest-hit regions could range from 10 to 20mm, and localized power outages cannot be ruled out. Travel conditions in the affected areas are expected to be hazardous due to ice accumulation on untreated surfaces. Consider postponing non-essential travel until late Wednesday and prepare for the likelihood of school bus cancellations throughout Central and Eastern Ontario.

Temperatures are forecast to rise gradually during the mid to late afternoon on Wednesday, which will change freezing rain to rain and help melt any ice accumulation. However, freezing rain may linger into the evening for the Ottawa Valley near the Quebec border.

In the meantime, the rest of Southern Ontario is expected to receive a soaking with 20 to 40mm of rainfall possible by the end of Wednesday. In some areas, particularly where thunderstorm activity occurs, rainfall amounts could be even higher, ranging from 50 to 75mm. This heavy rainfall may lead to localized flooding and ponding on roadways.

Additionally, there is potential for severe thunderstorms in Southwestern Ontario on Wednesday afternoon and early evening. While the strongest risk remains stateside, the possibility of storms crossing the border should not be overlooked, especially in areas like Windsor and Sarnia where the lakes have less influence. The main risks associated with these storms are strong wind gusts and even the chance of an isolated tornado can’t be ruled out. A thunderstorm risk map will be released later tonight and updated tomorrow as needed.

Be sure to stay informed and monitor weather updates as this potent storm system approaches. The impact of freezing rain, heavy rainfall, and possible severe thunderstorms, combined with significant ice accretion and potential power outages, could cause some disruptions to daily routines and travel plans.

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Spring on Pause: Wintry Blast Brings Snow, Ice, and Heavy Rain to Ontario This Weekend

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Forecaster: Brennen Perry

Published: Friday, March 24, 2023

As spring arrives on the calendar, it seems Mother Nature has a different plan for Ontario this weekend. An approaching low-pressure system from the US Midwest is set to bring a mix of wintry precipitation, starting Saturday morning and lingering into Sunday.

Early Saturday morning, rain will begin in Deep Southwestern Ontario, affecting areas like Windsor, Leamington, and Chatham. As the system moves northeastward, colder air will create freezing rain across much of Southwestern Ontario. The worst conditions are expected in elevated regions such as the Dundalk Highlands, along the Niagara Escarpment, and the Hamilton Mountains, including areas like Orangeville, Shelburne, Guelph, Kitchener, and Halton Hills. Freezing rain will last for several hours on Saturday morning and early afternoon. Some minor freezing rain could also be an issue across the GTA and the Niagara region, but areas closer to the lakeshore will see less ice due to slightly warmer temperatures.

By noon, many areas will transition from freezing rain to rain, but higher elevations may experience freezing rain for a few more hours. Central and Eastern Ontario will see snow starting in the early afternoon, with ice pellets mixing in later in the day. The extent of ice pellets is uncertain and may affect overall snowfall totals. As temperatures drop in the evening, any remaining precipitation will transition to flurries or light snow across Southern Ontario.

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Northeastern Ontario is in for a classic snowstorm, starting Saturday afternoon around Sudbury and North Bay. Heavy snow will continue into the evening and overnight, creating poor travel conditions across most of the southern portion of Northeastern Ontario, including Elliot Lake, Sudbury, North Bay, and Temiskaming Shores.

Overall accumulation will vary greatly, depending on the exact precipitation type and temperature. The highest snowfall totals will be in Northeastern Ontario, with up to 15-25cm possible. Central and Eastern Ontario can expect a quick 5-10cm of snow on Saturday afternoon before transitioning to ice pellets. Around 2-5cm of ice pellet accumulation is expected across Central and Eastern Ontario.

The worst icing is expected around Orangeville, Kitchener, Woodstock, Guelph, and York Region, with several millimetres of ice accretion possible. Some higher elevations could see 8-10mm of accretion, leading to ice damage and localized power outages. Heavy rainfall will also be a concern for Southwestern Ontario and the Golden Horseshoe, with up to 25-50mm of rainfall expected in Deep Southwestern Ontario, potentially causing flooding.

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Strong wind gusts will accompany the system, with the strongest gusts expected during the late morning and early afternoon hours on Saturday. Damaging gusts up to 90-100km/h are possible along the northeastern shoreline of Lake Erie, including Port Colborne and Welland. Occasional 90km/h gusts may also affect the Lake Ontario shoreline and Southwestern Ontario. Winds in Central and Eastern Ontario will range from 60-80km/h.

The combination of wintry weather and strong winds will likely lead to poor travel conditions, especially in areas experiencing freezing rain, ice pellets, and snow. It's advisable to avoid travel during the early part of Saturday. Conditions may improve slightly later in the day, but travel will likely remain difficult into Sunday.

Please note that this is a preliminary forecast and is subject to change. While confidence in the exact track is high, there could still be changes in precipitation type and timing. Stay tuned for an updated forecast by late Friday, including a detailed timeline for each region.

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Weekend Snow Squalls: Lake Effect Snow Brings Wintry Blast to Southern Ontario

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Forecaster: Brennen Perry

Published: Thursday, March 16, 2023

Prepare for a snowy and blustery weekend as snow squalls are set to develop east of Lake Huron and Georgian Bay. Early Saturday morning, strong southwesterly winds will form two snow squall bands – one off Lake Huron, stretching from Kincardine to Meaford, and another impacting areas northwest of Georgian Bay, such as Parry Sound, Britt, Sundridge, and surrounding communities.

As the day progresses, watch for these bands to shift southward, thanks to northwesterly winds. Grey-Bruce and Simcoe counties will find themselves in the crosshairs, with brief but intense pockets of heavy snow potentially drifting into the Greater Toronto Area (GTA) and Eastern Ontario during the afternoon and evening. Expect poor driving conditions in traditional snowbelt regions.

Snowfall totals will vary across the region. Hard-hit areas, including Grey-Bruce counties, Midland, Wasaga Beach, Orillia, Parry Sound, Britt, Sundridge, and nearby communities, can expect 10-20cm, with local accumulations up to 25cm. Central and Southwestern Ontario, as well as the western GTA, such as Kitchener-Waterloo, Guelph, and Mississauga, will likely see 5-10cm. The City of Toronto, Eastern Ontario, and Deep Southwestern Ontario are predicted to receive less than 5cm.

By Sunday morning, warmer temperatures will help ease the snow squalls, but not before they leave their mark.

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Snowstorm Takes Aim at Northern Ontario Starting Thursday With Up to 30-50cm of Snow Possible

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Forecaster: Brennen Perry

Published: Thursday, March 16, 2023

March has been relatively calm when it comes to the weather in Northern Ontario while Southern Ontario has experienced several winter storms. However, this pattern will change soon as a powerful system is expected to bring heavy snow to parts of Northern Ontario over the next few days. Some areas near Lake Superior, like Geraldton, Marathon, and Kapuskasing, could receive up to 50cm of snow.

The first bands of precipitation from this system will move in around Lake Superior on Thursday morning and afternoon. Most places will see heavy snow, but some rain might mix in around Sault Ste. Marie before turning into snow by evening. The snow will intensify late Thursday and continue overnight into Friday morning, with snowfall rates reaching 3-6cm per hour during the heaviest periods.

Strong winds, ranging from 50 to 70km/h, will combine with the snow to create extremely low visibility on roads. Some areas might even experience blizzard conditions, making travel nearly impossible and potentially causing road closures late Thursday and early Friday.

The snow will persist throughout Friday, though it will be less intense, with a few centimetres falling per hour. This will last until Saturday when the system is expected to leave the region by the afternoon.

The most severe conditions will impact areas from Thunder Bay to Timmins and Cochrane, with snowfall totals exceeding 20cm over two days and possibly reaching 50cm in some locations. Less snow is expected near the Manitoba border and further north, with less than 10cm forecasted.

To the south, along the Georgian Bay shoreline in areas like Elliot Lake, Sudbury, and North Bay, precipitation will be a mix of rain and snow or fully transition to rain. Snowfall accumulation will vary from trace amounts to 15cm. Southern Ontario will be affected primarily on Friday and Saturday, but it will experience heavy rain instead of snow. Rainfall totals will range from 15 to 30mm across Southern Ontario. A separate rainfall forecast will be posted on Thursday.

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UPDATE: Friday’s Snowmaker Stronger Than Expected and Could Deliver Up to 20cm of Snow to Parts of Southwestern Ontario and Golden Horseshoe

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Forecaster: Brennen Perry

Published: Thursday, March 9, 2023

As we end yet another week with some active weather, the latest data is indicating increased snowfall totals courtesy of a system that is expected to affect Southern Ontario on Friday.

The heaviest snow will be found in Deep Southwestern Ontario including Windsor, Chatham, Sarnia and London. These areas could see between 10 and 20cm starting early Friday morning and lasting through the afternoon.

Another zone southwest of Lake Ontario including Burlington, Hamilton and Grimsby could see some lake enhancement leading to snowfall totals near 20cm.

SNOWFALL TIMING

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The timing of this event is roughly unchanged from our initial forecast. We expect that the snow will begin starting in the far southwestern portion of our region during the early morning hours on Friday. Locations including Windsor and Sarnia will be the first to feel the impact of this system as it moves in from Michigan.

The heaviest snow will arrive just in time for the morning rush-hour throughout Southwestern Ontario with poor travel conditions from Windsor, Chatham, Sarnia and into London. Expect some delays and even some school bus cancellations can’t be ruled out so some children could get an early start to the March Break! More details on the chance of a ‘snow day’ will be covered in our nightly school bus cancellation forecast shortly.

By the late morning, we will start to see the initial bands of snow moving into the Golden Horseshoe bringing steady snowfall with a focus on the more western part of the region. This will continue throughout the morning and into the afternoon.

As mentioned, some locally heavier pockets of snow could develop over the higher elevations of the Niagara and Hamilton region southwest of Lake Ontario. This includes the Hamilton Mountain and Grimsby area with lake enhancement off Lake Ontario developing during the afternoon on Friday.

The snow is expected to taper off from west to east by the late afternoon and fully clear out of Southern Ontario just before the end of Friday.

SNOWFALL totals

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Total snowfall accumulation will be the highest in Southwestern Ontario with a general 10 to 20cm in locations including Windsor, Leamington, Chatham, Sarnia, London and St. Thomas. Parts of the Hamilton and Niagara region could also see up to 20cm thanks to the lake enhancement off Lake Ontario. It’s even possible that some localized pockets pick up over 20cm.

The rest of Southwestern Ontario from Goderich, K/W and into the Western GTA can expect around 8-16cm of snow. There will be a very tight gradient between the higher snowfall totals and trace accumulation so confidence is a little lower in the 2-6cm and 4-8cm zones including Toronto, York Region and Barrie.

We currently think Toronto will get around 5-7cm give or take a few centimetres while totals decrease to the north. Although there is the potential for some overachieving totals depending on where the lake enhancement sets up in the GTA. Little to no accumulation will be found in Central and Eastern Ontario.

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Yet Another End of the Week Snowstorm Could Bring Up to 10-20cm of Snow to Parts of Southern Ontario

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Forecaster: Brennen Perry

Published: Wednesday, March 8, 2023

Last week at this time we were monitoring what would be an impactful snowstorm that brought blizzard conditions and up to 20-30cm of snow between Friday and Saturday. Fast forward to this week, there’s a strong feeling of déjà vu in the air as yet another snowstorm is on the horizon for Friday. Fortunately, this system isn’t expected to be anywhere near as impactful as last week’s storm and won’t be as widespread.

Current indications suggest that the heaviest snow will be found in Deep Southwestern Ontario including Windsor, Chatham, Sarnia and London. These areas could see between 10 and 20cm starting early Friday morning and lasting through the afternoon. Lake enhancement off Lake Ontario may lead to higher snowfall totals around Hamilton and Grimsby.

SNOWFALL TIMING

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We expect that the snow will begin starting in the far southwestern portion of our region just after midnight. This means locations including Windsor and Sarnia will be the first to feel the impact of this system as it moves in from Michigan. There is some disagreement on the exact timing with some models suggesting a slightly later morning start although most models agree on it beginning sometime in the pre-dawn hours on Friday.

The heaviest snow will arrive just in time for the morning rush-hour throughout Southwestern Ontario with poor travel conditions from Windsor, Chatham, Sarnia and into London. Expect some delays and even some school bus cancellations can’t be ruled out so some children could get an early start to the March Break!

By the late morning, we will start to see the initial bands of snow moving into the Golden Horseshoe bringing steady snowfall with a focus on the more western part of the region. This will continue throughout the morning and into the afternoon. As mentioned, some locally heavier pockets of snow could develop over the higher elevations of the Niagara and Hamilton region southwest of Lake Ontario. This includes the Hamilton Mountain and Grimsby area with lake enhancement off Lake Ontario developing during the afternoon on Friday.

The snow is expected to taper off from west to east by the late afternoon and fully clear out of Southern Ontario just before the end of Friday.

SNOWFALL totals

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Total snowfall accumulation will be the highest in Southwestern Ontario with a general 10 to 15cm in locations including Windsor, Leamington, Chatham, Sarnia, London and St. Thomas. Some models suggest even higher totals exceeding 15cm, so we’ve used a more comprehensive range of 10-20cm for our forecast map in this area.

The rest of Southwestern Ontario from Goderich, K/W, Hamilton and Niagara region can expect around 8-16cm of snow. Although the higher numbers (12-16cm) will be mostly found southwest of Lake Ontario where lake enhancement will boost totals.

Less snow is expected to the north with between 2-6cm across much of the GTA and northern parts of Southwestern Ontario. Little to no accumulation will be found in Central and Eastern Ontario.

Keep in mind that this forecast has a moderate level of confidence as there is some disagreement on the models on how far north the heavier snow will extend into our region. We may need to shift the totals up in the more northern part of our forecast zones on Thursday if models start to show a more northern track.

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High Uncertainty With a Potential Snowmaker to Impact Southwestern Ontario on Monday

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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.

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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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UPDATED: Significant Blizzard to Hit Southern Ontario on Friday and Saturday; Up to 25-40cm of Snow Possible

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UPDATED fORECAST

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Forecaster: Brennen Perry

Published: Friday, March 3, 2023

Based on the latest data, we have made some slight adjustments to our snowfall forecast for Friday into Saturday. For most regions, this means that the expected snowfall totals have increased compared to our previous forecast. With intense snowfall rates approaching 5-10cm/hour at the height of this storm by Friday night, it’s almost guaranteed to have a crippling impact on travel across much of Southern Ontario. Strong wind gusts developing tonight and lasting into Saturday morning could reach up to 60-90km/h leading to blizzard conditions and near-zero visibility.

It can’t be repeated enough: DO NOT TRAVEL TONIGHT OTHER THAN FOR ESSENTIAL PURPOSES!! Please let road crews and emergency officials do their job tonight and stay off the roads. Highway closures even in urban areas including the GTA can’t be ruled out similar to what we saw during the blizzard in January 2022.

From Environment Canada’s latest updated Winter Storm Warning for the GTA;

“Significant winter storm with dangerous travel conditions expected tonight. Non-essential travel strongly discouraged.”

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High-resolution models consistently show a fairly expansive zone encompassing much of the Golden Horseshoe from Hamilton through the GTA and into Kingston getting the worst of this storm. Snow will quickly pile up starting in the early evening with heavier bands of snow affecting the region by midnight. While 25-40cm may seem like an average to slightly above average snowstorm for most, the important aspect of this event is that it will come within such a short timeframe. If we get the 5-10cm hourly snowfall rates some models are suggesting, it would only take a few hours to get the forecasted amount. This isn’t a multi-day or even 24-hour snowfall event which would give road crews time to keep the main roads cleared. This will be impossible to keep up with the rapid snowfall accumulation.

There are strong indications of this storm ‘overachieving’ based on the latest data hence why we’ve increased the maximum expected snowfall accumulation from 20-35cm to 25-40cm. This may even still be too low so some areas could approach our ‘local max’ as indicated on the legend. Especially considering that this system will be further enhanced by Lake Ontario which can be hard to nail down in advance. Thundersnow is also quite possible so don’t be surprised to see some lightning with the snow tonight!

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The forecast gets tricky further south along the Lake Erie shoreline. Models are having a hard time handling the potential for mixed precipitation in Deep Southwestern Ontario. Depending on how much mixing with ice pellets and rain occurs, it could lead to substantially less snowfall accumulation. But on the other hand, if it stays all snow then we could be looking at 20+cm for locations such as Windsor, Chatham and Port Colborne. We’ve lowered the expected accumulation to 5-10cm directly along the Lake Erie shoreline with closer to 10-15cm further north in Windsor and Chatham.

In Eastern and Central Ontario, we’ve increased the snowfall totals there as well because the system is expected to have more moisture to work with on its northern flank. This will allow for widespread snowfall accumulation of 10-25cm across Muskoka, Bancroft and into the Ottawa Valley. Less snow is still expected the further north you go, with less than 5cm of snow in Northeastern Ontario.

PREVIOUS fORECAST

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Forecaster: Brennen Perry

Published: Thursday, March 2, 2023

The concern is growing for what could be the most impactful system we’ve seen in Southern Ontario since last January when a potent blizzard left many stuck in widespread snowfall totals of 30-50cm. This upcoming storm has some similarities in terms of intensity and impacted areas compared to the January 2022 storm, but will likely fail to reach the 50+cm snowfall totals we saw last year. As we end off the first (partial) week of ‘meteorological spring’, it certainly won’t feel like that across Southern Ontario with an approaching system from the southwest expected to move into our region starting Friday afternoon.

Current indications suggest that this system will deliver a significant dumping of snow across a wide swath of Southern Ontario including Southwestern Ontario, the Golden Horseshoe and into Eastern Ontario. Combined with strong wind gusts near 60-80km/h and intense snowfall rates, conditions will quickly deteriorate during the evening on Friday and continue overnight, into Saturday morning.

Travel will be near impossible in the affected region from 6 PM on Friday and into pre-dawn on Saturday due to near-zero visibility and rapid snow accumulation. This may even lead to several highway and road closures around the Golden Horseshoe and into Southwestern Ontario where the worst conditions are expected. If you can, please stay off the roads starting Friday evening!

There is some disagreement amongst the models on the exact snowfall totals with some differing on the track which could lead to more ice pellets mixing in along the Lake Erie and Lake Ontario shorelines. As a result, we may need to make some adjustments to the forecast by Friday afternoon based on the latest data. Either way, we are looking at a very impactful storm across Southern Ontario.

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The first effects of this storm will be felt in Deep Southwestern Ontario with bands of light to moderate snowfall moving into the region just after the noon hour. Heavier snow will begin to build into Southwestern Ontario by the mid to late afternoon which is when we also expect to see the wind start to pick up.

Blowing snow and localized blizzard conditions are expected by the late afternoon in Southwestern Ontario. The temperature gradient will be extremely tight meaning some areas near the Lake Erie shoreline could mix in some ice pellets and rain later on Friday which would reduce the overall snowfall totals in the Windsor, Leamington and Chatham regions.

As we head into the dinner hour on Friday, this storm will encompass much of Southwestern Ontario as it approaches the Golden Horseshoe. Conditions are expected to quickly deteriorate just after 6 PM across the Golden Horseshoe as the snowfall rate rapidly increases from a few centimetres per hour in the late afternoon to 3-6cm/hour by the early evening.

Treacherous conditions will continue throughout the evening and into the early overnight hours with the most intense snowfall rates just before midnight. Most of the snow from this storm will come during a 6-12 hour timeframe which is expected to further enhance the impact due to blowing snow as road crews are unable to keep up with the intense snowfall rates.

For Central and Eastern Ontario, there is some disagreement on exactly how far north the bands of snow will make it into our region. Some models show a tighter gradient with the heavy snow which would lead to lighter snow for the more northern parts of Southern Ontario. The snow is expected to start by the early evening (late evening in the Ottawa Valley) and continue steadily overnight into Saturday morning.

Conditions should begin to improve by the mid to late morning on Saturday as the system exits our region. Although keep in mind that many roads will likely still be snow-covered and it could take a good portion of the weekend before everything is fully cleaned up so expect some lingering impacts throughout Saturday.

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In terms of the worst impact, we expect blizzard conditions to be quite widespread affecting Sarnia, London, Hamilton, K/W, GTA, Barrie, Peterborough and Kingston. Wind gusts ranging from 50-80km/h combined with the heavy snow will lead to whiteout conditions mainly between 5 PM and 2 AM on Friday. Those near the Lake Erie shoreline and into the Niagara region could mix in some ice pellets leading to lower snowfall accumulation although a moderate impact is still expected.

While the focus of this event won’t necessarily be on the total accumulation, it will certainly be an important component. Current data suggests the highest totals will be found right around the Golden Horseshoe thanks to potential lake enhancement off the western shoreline. As such, much of the GTA and into Southeastern Ontario is on track to see between 20-30cm with maybe as much as 35-40cm in some pockets.

The more extreme totals will likely be found in the higher elevations away from the shoreline including the Dundalk Highlands (Orangeville, Guelph etc.) and just north of the GTA around Vaughan and Richmond Hill. Those near the shorelines including Toronto, Hamilton, Burlington and Oshawa will pick up closer to 20cm (or even less if we see some mixing occur).

General snowfall totals in Southwestern Ontario will range from 15 to 25cm including Sarnia, London and Goderich. The slightly lower totals are due to the potential for ice pellets along with the snow expected to be denser as temperatures will be close to the freezing mark leading to lower liquid-to-snow ratios. Between 10 to 20cm is expected along the Lake Erie shoreline in Deep Southwestern Ontario and could even end up lower than 10cm should temperatures end up warmer than expected and result in a switchover to rain.

As we have mentioned, there is a significant disagreement on the totals through Central and Eastern Ontario. Some models suggest that the Ottawa region could pick up close to 20-25cm while others show less than 10cm so there is a lot of variance in the numbers. At this point, we’re going with a widespread 10-20cm although the potential is there for up to locally 25cm. Once you get into the more northern sections of Southern Ontario including Muskoka, Bancroft and Pembroke, we are looking at around 6-12cm of snow possible although this area may fail to see much snow should the precipitation stay further south.

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Potential Late-Week Snowstorm Could Bring Over 20cm of Snow and Blizzard Conditions to Southern Ontario

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Forecaster: Brennen Perry

Published: Tuesday, February 28, 2023

While Wednesday marks the first day of meteorological spring, Mother Nature has other plans with yet another impactful storm on the way. Our concern for this system has continued to grow over the past few days as models consistently point towards a potential significant snowfall across a wide swath of Southern Ontario. It appears the snow will start midday on Friday and continue overnight into Saturday. Strong wind gusts approaching 50-80km/h could lead to blowing snow and even blizzard conditions in some areas.

The tricky part with this system is narrowing down the exact path which dictates who gets the highest snowfall totals. We are still several days away and models have been split into two scenarios. So far the most consistent scenario currently shared by the American and Canadian models (with the Canadian slightly more south) has the centre of the low-pressure tracking south of Lake Erie. This would mostly keep our region on the colder side of the system, leading to predominantly a heavy snowfall event. 

As shown on our first map above for Scenario #1, the highest snowfall totals would extend from Lake Huron through the GTA and into Southeastern Ontario. While we aren’t going to get too specific about snowfall totals as it’s too early, we can say there is a good chance those regions will see well over 20cm of accumulation in this scenario. The American model (GFS) has been particularly aggressive regarding snowfall totals showing widespread 30-40cm which would be very significant. This is more of the worst-case scenario, but it’s important to mention, as it can become a reality which we saw last winter.

For Deep Southwestern Ontario and the Niagara region, they will see a mix of mainly ice pellets and snow along with some freezing rain. They could also see significant snowfall accumulation, but confidence is lower due to the potential for ice pellets reducing the overall totals. Less snow will be found to the north across Central and Eastern Ontario. Although there is some disagreement on the exact location of the cut-off of the extreme northern edge of this system. Expect up to 10-15cm in the more southern sections of Central and Eastern Ontario, slowly dropping off closer to 5cm as you get further north.

NOTE: You can click on the map to open a zoomable image which will be easier to read.

On the other hand, the European model has been suggesting a different scenario that has the system further to the north. A more northern track takes the centre of the low pressure to the north of Lake Erie. As a result, this would put the heaviest bands of snow over Central and Eastern Ontario which we’ve outlined in our map for Scenario #2. While those in Southwestern Ontario and along the Golden Horseshoe see a messy mix of snow, ice pellets, freezing rain and rain as they end up right on the line between the cold and warm air.

This would be quite similar to the last few events we have seen across Southern Ontario, however, it does appear there will be less of a freezing rain component to this storm. The main precipitation types will be snow, ice pellets and even rain depending on which scenario wins out. There will be more moisture for this system to work with as it taps into the Gulf of Mexico and will be overall stronger based on the pressure. So the impacts of this storm will likely differ compared to the past few storms and likely not in a good way.

Strong wind gusts combined with intense snowfall rates will lead to blinding whiteouts at the height of this event and may even result in some road/highway closures late Friday into Saturday. There could be a significant impact on the evening commute on Friday depending on the exact timing. It’s right on the fence and hopefully is delayed by a few hours to push the worst impact into the overnight hours when fewer people are on the roads.

Again, lots can change between now and Friday, but the confidence is slowly growing in some form of an impactful winter storm across Southern Ontario to end the weekend. Somewhere in Southern Ontario is going to likely see over 20cm between Friday and Saturday. This isn’t a guarantee that a specific location will see a major snowfall. The potential is there which is our focus - we want you to be prepared for the worst, but hope for the best! We will continue to monitor each new set of model data and provide more precise details throughout the week. Stay tuned!

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February Set to Go Out Like a Lion as Southern Ontario Is Targeted by Another Winter Storm on Monday

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Updated forecast

NOTE: You can click on the map to open a zoomable image which will be easier to read.

Forecaster: Brennen Perry

Published: Sunday, February 26, 2023

Déjà vu, anyone? After reviewing the latest model data on the upcoming system for Southern Ontario, it looks like the colder air will win over across much of the region. We have adjusted our forecast moving the heavy snow zone further south into Central and Eastern Ontario. The freezing rain risk now covers an almost identical area as last week's storm with the heaviest icing expected across Sarnia through London and into the Hamilton/Niagara region. For the rest of Southwestern Ontario and into the GTA, we are looking at a mixed bag of precipitation including brief freezing rain, ice pellets and snow.

The timeframe of this winter storm is fairly similar to our initial forecast with precipitation expected to start during the late morning hours in Deep Southwestern Ontario and spreading northward throughout the afternoon. It will likely begin as freezing rain in the Windsor/Chatham region before transitioning over to rain as temperatures rise above the freezing mark by the dinner hour. As mentioned, those in the Sarnia, London and Hamilton corridor will see more prolonged freezing rain during the afternoon and evening where the cold air is expected to hold on.

We are also looking at a big impact on the evening commute as heavy snow and ice pellets affect the Golden Horseshoe starting during the late afternoon and continuing through the evening. There is still some disagreement on the exact temperature in this area, especially closer to the shoreline of Lake Ontario which would dictate the main precipitation type. Current indications suggest it should start as some heavy wet snow before transitioning over to ice pellets and even some freezing rain. Later in the evening and overnight, there is the potential that temperatures climb above the freezing mark around the shoreline leading to a transition over to rain.

For Central and Eastern Ontario, snowfall will start during the early evening hours, continuing throughout the overnight and into Tuesday morning. Strong to damaging wind gusts may also accompany this system with gusts expected to reach 60-80km/h by late Monday and may even come close to 90km/h east of Lake Huron. This could lead to power outages in the areas that received heavy freezing rain earlier in the day and blowing snow for those further north.

Everything will come to an end by Tuesday afternoon as the system moves out of our region. Total snowfall accumulation across Central and Eastern Ontario is expected to range from 10 to 15cm with some localized pockets (especially in the Ottawa Valley) picking up to 20cm. The icing from this event isn't expected to come near what we saw last week, but up to 4-8mm of ice accretion is possible in the hardest-hit region. Those in between the snow and freezing rain including much of Southwestern Ontario into the GTA will see a bit of everything so the exact totals are difficult to predict depending on the exact temperature.

PREVIOUS fORECAST

NOTE: You can click on the map to open a zoomable image which will be easier to read.

Forecaster: Brennen Perry

Published: Saturday, February 25, 2023

It has certainly been an active month across Southern Ontario regarding the weather as we’ve experienced almost all the seasons over the past few weeks. This includes temperatures on both extremes from wind chills in the -30s to spring-like temperatures well into the teens. It shouldn’t be a surprise that February is set to conclude with a bang across our region as yet another messy winter storm is on the horizon for Monday into Tuesday. Impacts will vary across the region from heavy snow in Central and Eastern Ontario to potentially several hours of freezing rain in the south.

There is still some uncertainty regarding the exact intensity and timing of this storm so it’s quite likely there are some changes to the forecast as we get closer to Monday. At this point, it appears precipitation will start during the late morning or early afternoon on Monday in Deep Southwestern Ontario. With temperatures expected to be just above the freezing mark in the Windsor/Chatham area, it should come down in the form of rain. Total rainfall accumulation throughout this event will range from 10-20mm.

As the precipitation spreads further north throughout the afternoon it will encounter some colder temperatures east of Lake Huron and into the Golden Horseshoe. As a result, a fairly expansive zone of freezing rain will develop and impact Sarnia, London, Goderich, K/W and Guelph along with parts of the GTA away from the shoreline throughout the afternoon and early evening. This could lead to icy road conditions just in time for the evening commute on Monday so plan to leave extra time to get to your destination and drive according to the conditions!

The forecast gets tricky for those in the GTA around the Lake Ontario shoreline and into the Niagara region as temperatures will be very close to the freezing mark. Brief freezing rain is possible before it slowly transitions over to rain although if this transition is slower then more icing is possible. The Niagara region will likely see minimal freezing rain as the temperature is expected to rise faster there compared to other areas.

While this system isn’t expected to be as significant as last week’s storm that brought heavy ice accretion from freezing rain, the timeframe will be very similar as we see the worst impacts primarily during the evening across Southwestern Ontario and the Golden Horseshoe. Freezing rain will begin to transition over to rain in Southwestern Ontario as the temperature slowly climbs above the freezing mark during the evening and early overnight.

Total ice accretion could range from 5-10mm in the hardest hit regions, but this should melt away fairly quickly unlikely last week which would limit the overall impact. It may still result in some localized power outages with a thin layer of ice developing on untreated surfaces including trees and power lines.

Further north across Central and Eastern Ontario, we are looking at mostly snowfall with ice pellets mixed in for regions south of Lake Simcoe. Snow will start during the late afternoon and continue throughout the evening and overnight. Total snowfall accumulation is expected to range from 6 to 16cm with the highest totals in the more northern parts of our region. Those in Northeastern Ontario including Elliot Lake, Sudbury and North Bay could see up to 20cm of snow. We expect to see the snow come to an end by the noon hour on Tuesday.

As mentioned, this is a preliminary forecast as there is some uncertainty on how long the cold temperatures will hold on which would affect the overall ice accretion. There is more confidence in the snowfall portion of this event so if we make any changes, it will likely be in Southwestern Ontario and the Golden Horseshoe once we get a better idea of how quickly the switchover will occur. Check back on Sunday for a more detailed forecast.

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Major Ice Storm Targets Southern Ontario Starting Wednesday & Significant Snowstorm for Central and Eastern Ontario

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Forecaster: Brennen Perry

Published: Tuesday, February 21, 2023

While this month has been a roller coaster when it comes to the weather across Southern Ontario, we are heading back to winter as a major winter storm targets our region over the next few days. This will come in the form of prolonged freezing rain for Southwestern Ontario, ice pellets across the GTA and heavy snow in Central and Eastern Ontario. Precipitation is expected to start Wednesday morning lasting into Thursday. The storm will have a significant impact to travel across Southern Ontario and widespread power outages are likely in the region that sees freezing rain.

Initial bands of precipitation associated with this system are expected to reach the Canadian border in Deep Southwestern Ontario from Michigan around the noon hour. It will likely start as some light snow mixed with ice pellets before changing over to ice pellets and freezing rain by the early afternoon. Snow will also spread further to the northeast, reaching Southwestern Ontario and the GTA by the mid-afternoon. This will lead to rapid snowfall accumulation over the afternoon before it transitions over to ice pellets.

Conditions will continue to progressively worsen into the evening with intense icing ongoing from Sarnia through London and into Hamilton right at the height of the rush hour. Heavy ice pellets will be a concern throughout the GTA mixed in with snow and some freezing rain. Snow will start to affect Central and Eastern Ontario by the late evening continuing overnight. Some parts of Deep Southwestern Ontario including Windsor, Chatham and along the Lake Erie shoreline may inch above the freezing mark overnight which would reduce the freezing rain impact.

Conditions will be very treacherous starting from Wednesday late afternoon and into the predawn hours on Thursday. Travel should be avoided if possible until continues to improve later Thursday. Especially in the area expecting significant ice accretion with a thick layer of ice developing on untreated surfaces.

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Strong winds gusting between 60-80km/h are also expected by the evening on Wednesday and continuing overnight. This will further enhance the impact of both the freezing rain leading to power outages and blowing ice pellets/snow or even localized blizzard conditions in areas further north.

Precipitation will slowly taper off from west to east beginning just after midnight. So the worst of the freezing rain will be finished by the early morning hours on Thursday. While snow will continue across Central and Eastern Ontario throughout the morning.

Another round of precipitation will move across our region during the afternoon on Thursday bringing patchy freezing rain throughout Southwestern Ontario and the GTA. Further north, we will see ice pellets or light snow across Central and Eastern Ontario during the afternoon and evening.

As the system finally exits our region by late Thursday, it will usher in much cooler air in time for the weekend. Morning lows on Friday could dip into the -20s for some parts of Southern Ontario!

NOTE: You can click on the map to open a zoomable image which will be easier to read.

When it comes to the overall ice accretion and snowfall accumulation, the forecast becomes tricky as it will depend on the exact surface temperature. Even if the temperature is a fraction of a degree colder or warmer than expected, it could mean the difference between heavy freezing rain and rain or ice pellets. As such, it’s important to focus on the overall impact which is expected to be similar no matter if you see freezing rain, ice pellets or snow.

With that being said, we believe the hardest-hit area when it comes to the freezing rain will extend from Sarnia through London and into Woodstock. This zone could pick up to 15-30mm of ice accretion, but this will depend on the surface. For Windsor and Chatham into the Hamilton/Niagara region, ice accretion is expected to range from 6-12mm and maybe up to 15mm in localized pockets (especially in more elevated regions like the Hamilton Mountain). Less freezing rain is expected the further north you go as we see more ice pellets and snow across the GTA and Central/Eastern Ontario.

NOTE: You can click on the map to open a zoomable image which will be easier to read.

The focus on the snow will be in Eastern Ontario where the Ottawa Valley is likely to see 25-40cm of accumulation by the end of Thursday. It should be noted that some models are showing less moisture making that far north so the potential for this region to underperform the forecast isn’t out of the question. For the rest of Eastern and Central Ontario, snowfall totals will end up somewhere around 15-30cm.

As we go south of Lake Simcoe the snowfall accumulation will become less clear as ice pellets mix in and reduce the overall snow total. We are looking at 10-20cm from Goderich and into the Toronto region although that could end up on the lower end due to the ice pellets. And less than 10cm of snow is expected through Deep Southwestern Ontario and north of Lake Erie where freezing rain is the concern.

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Potential Snow and Ice Storm Threatens to Bring Significant Disruptions Across Southern Ontario Starting Wednesday

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NOTE: You can click on the map to open a zoomable image which will be easier to read.

Forecaster: Brennen Perry

Published: Sunday, February 19, 2023

The concern is growing over a system expected to affect Southern Ontario as early as Wednesday afternoon and continuing into Thursday. The two main stories expected to dominate with this system’s impact on our region will be the heavy snow to the north and prolonged freezing rain to the south. Total snow accumulation could approach 20-30cm in the hardest-hit locations by the end of Thursday. Significant ice accretion is possible in the areas that see freezing rain with up to 10-25mm of accretion.

Where the mixing line is located will dictate who sees what in terms of precipitation. Most of the latest models agree on a rough track that could put much of Southern Ontario on the snow side of the storm north of a line from Goderich and Toronto. Those closest to the mixing line will experience a mix of ice pellets and snow with total accumulation ranging from 10-20cm including both snow and ice pellets. And further to the north including Central and Eastern Ontario, we are expecting snow to be the main concern with up to 15-30cm of accumulation possible. Do note that there is some uncertainty on how far north the moisture associated with this system will get. So it’s possible that if the system tracks further to the south, those in the far north of our forecast region including Sudbury, North Bay, Algonquin Park and Ottawa will see lower snowfall totals.

Meanwhile, those to the south including Windsor, Sarnia, London, K/W, Hamilton and Niagara will see a mix of ice pellets and heavy freezing rain. This freezing rain could be quite persistent lasting from Wednesday evening through to Thursday afternoon. Almost 12-16 hours of freezing rain will surely lead to a significant impact in the affected regions including making travel near impossible and potential power outages! This will also be followed by some strong to damaging winds late Thursday into early Friday which could lead to even more damage from ice-covered surfaces.

As this storm is still several days away, we can’t get into too many details on the exact timing as that will likely shift around as we get closer to Wednesday. However, it appears likely that the worst conditions will occur during the evening and overnight hours on Wednesday continuing into Thursday. As a result, expect bad travel conditions for the evening commute on Wednesday and the morning commute on Thursday. This will almost certainly lead to widespread school bus cancellations for Thursday.

We will be closely following the latest data over the next few days and will have a more detailed forecast including exact timing and accumulations. As mentioned, there is still plenty of time for the models to change so expect to see at least some changes in terms of location and overall accumulation. We hope this does change as the current scenario doesn’t look good on the effects it could have on Southern Ontario.

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Freezing Rain Threat Looms for Southern Ontario on Thursday With a Potential Flash Freeze on Friday

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NOTE: You can click on the map to open a zoomable image which will be easier to read.

The rollercoaster of seasons across Southern Ontario continues as we end another week with a potentially messy winter storm. We’ve been treated with fairly mild weather making many think that spring is here - even the rodent weather prognosticator! But we are in Canada after all and winter is far from done with our region.

And that blast of reality is under 24 hours away as we see the risk of prolonged freezing rain across a large swatch of Southern Ontario along with heavy sleet and snow starting Thursday afternoon. It will be followed by a rapid cooldown on Friday morning bringing temperatures well below the freezing mark in time for the weekend. The fact that the extended freezing rain will be followed by a deep freeze is concerning as usually, we see a rise in temperature allowing for any ice to quickly melt. That won’t be the case this time which could lead to longer-lasting impacts including damage from the ice and power outages.

Precipitation will start just after the lunch hour in Deep Southwestern Ontario. For the most part, it looks like freezing rain will be the predominant precipitation type. However, the temperature could be slightly above the freezing mark, especially along the Lake Erie shoreline leading to less freezing rain. May also see some ice pellets further north for regions east of Lake Huron and even some wet snow for the Grey-Bruce region.

The band of freezing rain will continue to expand to the northeast across the Golden Horseshoe by the late afternoon and Southeastern Ontario by the dinner hour. Again, the temperature will be a big factor in determining the overall impact making this forecast a tricky one. Currently, it looks like the cold air will win over with this system allowing for prolonged freezing rain. Although we could see less icing in areas along the shorelines including Hamilton, Toronto and the Niagara region should the temperature stay just above the freezing mark.

Ice accretion in the hardest hit regions could range from 5-10mm by early Friday morning which is when we expect to see the freezing rain come to an end. Less accretion is expected further north and along the shoreline of Lake Ontario and Erie with between 2-6mm of accretion possible.

For Central and Eastern Ontario (including the Ottawa Valley), the story with this storm will be a mix of ice pellets and snow starting Thursday evening and continuing into Friday morning. Overall accumulation here will range from 8 to 16cm of snow along with up to 2-6cm of ice pellets. Snow will come to an end by late Friday morning so expect some impact on the morning commute including possible school bus cancellations. We will have more information on that in our daily ‘snow day’ forecast here.

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Heavy Rain, Damaging Wind Gusts and Freezing Rain Risk to Impact Southern Ontario on Thursday

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NOTE: You can click on the map to open a zoomable image which will be easier to read.

As we end the first full week of February, a messy system is on the horizon for Southern Ontario on Thursday. Parts of our region could see up to 20-40mm of rainfall, damaging wind gusts near 90-100km/h for parts of the Lake Erie shoreline and several hours of freezing rain for Eastern Ontario. There is even the risk of non-severe thunderstorms in Deep Southwestern Ontario late Thursday!

This is all expected to start early Thursday morning as we see the first bands of precipitation enter Southwestern Ontario just after midnight. Temperatures for the most part will be above the freezing mark keeping any precipitation in the form of rain. However, we believe a pocket of colder air will lock in over the Dundalk Highlands keeping them just below the freezing mark for a few hours during the mid-morning hours. This means locations such as Hanover, Guelph, Kitchener, Orangeville and Shelburne could experience some freezing rain before temperatures warm up by late morning. Ice accretion of a few millimetres is possible in the hardest hit areas which will be the higher elevations northwest of the GTA.

By the afternoon on Thursday, the freezing rain risk will shift to the Ottawa Valley as we see the potential for prolonged freezing rain. This risk could linger into the evening with persistent freezing rain lasting 4-8 hours before tapering off just after midnight. Expect icy road conditions and even the possibility of localized power outages as total ice accretion could range from 5-10mm. The Algonquin Park region into areas just north of Muskoka will see some freezing rain, but snow and ice pellets will also mix in at times which means less icing is expected there. Snow will be the story in Northeastern Ontario where Sudbury and North Bay could see 10-20cm of snowfall accumulation by the end of Thursday.

NOTE: You can click on the map to open a zoomable image which will be easier to read.

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Another concern with this system will bring strong to damaging wind gusts developing throughout the day on Thursday. The strongest gusts will be found along the northeastern shoreline of Lake Erie including Norfolk County and the Niagara region. These areas could see gusts exceeding 90km/h mainly during the afternoon and evening hours.

For the rest of Deep Southwestern Ontario, through the GTA and Lake Ontario shoreline, we will see strong winds with gusts around 80-90km/h, but it will be just below severe levels. Wind gusts of between 70-80km/h are possible from Southwestern Ontario through Lake Simcoe and into Southeastern Ontario. Central Ontario and the Ottawa Valley will see gusts remain under 70km/h.

NOTE: You can click on the map to open a zoomable image which will be easier to read.

While much of Southern Ontario will escape the freezing rain risk, there is another threat lurking with this system. That is the heavy rainfall with widespread totals ranging from 20-40mm including Southwestern Ontario, the Golden Horseshoe and parts of Eastern Ontario. This amount of rain during winter is quite significant and could lead to localized flooding in some areas.

Rainfall totals of between 15-30mm are expected from the Bruce Peninsula through Central Ontario and the Ottawa Valley. Less rain is expected in the more northern parts of Southern Ontario due to more freezing rain, ice pellets and snow. Although the flooding threat is still a concern as it will lead to the same amount of water once melted.

Be sure to stay safe and dry!

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Snow Squalls Target Parts of Southern Ontario on Friday With Up to 15-30cm Possible

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February is starting on a chilly note across Southern Ontario with the arrival of extremely cold temperatures late Thursday. This is courtesy of a sharp cold front cutting across the region which also sparked an intense snow squall that brought a brief shot of heavy snow across Southern Ontario on Thursday afternoon and evening.

For more information on the upcoming extreme cold, please check out our temperature forecast HERE

At this point in the winter, lake effect snow is usually not a concern considering that the lakes tend to be frozen over by now. That isn’t the case this year as the rather mild winter has led to very little ice coverage on the lakes. The bitterly cold air combined with a strong northwesterly flow will result in the development of snow squall activity off the southeastern shorelines of Lake Huron and Georgian Bay.

Bands of lake effect snow are expected to organize late Thursday evening or early Friday morning in the wake of the cold front passing through. The hardest hit regions appear to be the Grey-Bruce, Huron and Perth counties east of Lake Huron along with the southeastern shoreline of Georgian Bay including Collingwood and Wasaga Beach. Snow squalls will be ongoing throughout the day on Friday leading to locally hazardous conditions due to near-zero visibility and rapid snowfall accumulation. Travel within the affected regions is not recommended and at the bare minimum, be sure to leave plenty of time to get to your destination.

By the end of the day on Friday, we are looking at the highest snowfall totals ranging from 15-30cm including much of the regions east of Lake Huron and the Collingwood/Wasaga Beach area. Surrounding regions including Barrie and London could see some occasional snow squall activity as it shifts around throughout the day. Snowfall totals here could approach 10-20cm although this depends on the exact location of the squalls.

Snow squalls from Georgian Bay may also affect the Northern GTA including York Region and the Hwy 400 corridor between Barrie and Vaughan. We don’t expect anything overly significant in terms of accumulation here with up to 10cm, but the sudden whiteouts would be a big concern when it comes to driving conditions.

The lake effect snow is expected to briefly come to an end late Friday as a weak system moves into the region from the northwest early Saturday morning. Snow squalls may redevelop northeast of Georgian Bay on the weekend leading to accumulating snow around Parry Sound and North Bay. More details on that in a separate forecast to be posted on Friday.

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January Is Ending on a Snowy Note Across Southern Ontario With a System to Dump Up to 15-25cm of Snow on Sunday

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UPDATED FORECAST

ISSUED: Saturday, Jan. 28, 2023 (2:00 PM)

Southern Ontario is bracing for yet another impactful snowstorm this weekend, with the latest data shifting the heaviest snowfall totals further south, extending from Kincardine through Collingwood, Muskoka, Bancroft, and Renfrew. Snowfall totals here will range from 15 to 25cm with locally up to 30cm.

Based on the southern shift, we are now expecting less mixing through the Greater Toronto Area (GTA), boosting potential snowfall totals ranging from 5-10cm along the lakeshore and up to 10-15cm further inland. Eastern Ontario is expecting 10-20cm, with slightly less in Prince Edward County due to rain mixing in near the Lake Ontario shoreline. The heaviest snow is expected to occur during the mid to late morning hours on Sunday.

Wet flurries transitioning to rain are expected by mid-morning in Deep Southwestern Ontario and the Niagara region, with snow tapering off by the afternoon as the system exits the region and moves into Quebec.

ORIGINAL FORECAST

NOTE: You can click on the map to open a zoomable image which will be easier to read.

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While the weather started mild and quiet for most of Southern Ontario to begin the first month of 2023, the same can’t be said as we say goodbye to the remaining days of January. We are monitoring yet another potential storm that could bring significant snow to parts of the region on Sunday. This comes only days after a system dumped up to 20-25cm of snow across Southern Ontario on Wednesday leading to hazardous driving conditions and a lengthy cleanup that lasted throughout the week.

With this upcoming event, it will feel like deja vu as we experience similar totals, but the track appears to be slightly further north. This will mean that higher snowfall totals will be found east of Lake Huron and Georgian Bay as lake enhancement becomes a key component in providing extra moisture. While to the south, we could see some mixing in Deep Southwestern Ontario and around the Golden Horseshoe making for a tricky forecast regarding the overall snowfall totals.

We debated on even releasing a forecast this evening as models still disagree on where this mixing line will be located. Some models show less mixing around the GTA, allowing for snowfall totals to exceed 10cm. On the other hand, some models show a switchover to rain (especially closer to the shorelines) which would keep snow totals closer to a few centimetres if anything at all. This is why we emphasize that the forecast right now is very preliminary and will likely change once we get more data tonight and on Saturday.

Snow is expected to start late Saturday or pre-dawn Sunday as the system moves in from the west. The bulk of the snow will fall during the morning hours which is when we expect the worst conditions. It will begin to taper off later in the day with just scattered flurries by the late afternoon through the evening. For Southwestern Ontario, the precipitation will start as wet snow or showers and transition over to rain by the late morning. There is the potential for some brief freezing rain during the transition, but the environment isn’t favourable for widespread freezing rain.

Again as mentioned, the exact snowfall totals are still a little uncertain depending on the track and the extent of rain mixing in and reducing the snow accumulation. We do believe that a fairly widespread zone including the Grey-Bruce region, into Muskoka, Parry Sound and Bancroft could pick up between 15 to 25cm. Some models even indicate locally higher totals exceeding 30cm, but we’ve decided to stick to the 15-25cm range due to the uncertainty. An upgrade to the 20-30cm level in some areas isn’t out of the question.

Accumulation will drop off to the south with expected totals ranging from 10 to 20cm in locations such as Goderich, Northern Simcoe County, Peterborough and the Ottawa Valley. Southwestern Ontario and the GTA are currently on the line between very little snowfall accumulation and 10+ cm of accumulation. We will finalize this in our updated forecast on Saturday and provide a more exact accumulation range once we get a better idea of the extent of the mixing.

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Midweek Snowstorm on Track to Bring Up to 15-25cm of Snow Across Southern Ontario

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A Texas low is set to affect Southern Ontario starting Wednesday, bringing something many across the region have been lacking this year, accumulating snow! The upcoming snowfall event will likely be the most significant thus far in the season for many areas excluding the lake effect snow we saw around Christmas. Widespread snowfall totals will range from 10-25cm with the highest amounts around the Golden Horseshoe and into Eastern Ontario. The heaviest snowfall will occur during the late afternoon and evening hours on Wednesday, making for a very tricky evening commute with snow-covered roads and reduced visibility.

There is still some uncertainty on the exact speed and strength of the system which could change the forecast slightly, but confidence is high enough to provide a rough idea in regards to timing and accumulation. Just keep in mind that this is a preliminary forecast and may need to be adjusted as we get closer to Wednesday. An updated forecast will be released late Tuesday based on the latest data.

We expect that the initial bands of snow will start to move into Deep Southwestern Ontario and areas around the Lake Erie shoreline by late Wednesday morning. Light to moderate snow will be ongoing throughout the afternoon and will continue to intensify later in the day as it approaches the Golden Horseshoe and the rest of Southwestern Ontario. As mentioned, we will see the most intense snowfall rates of up to 2-3cm per hour right during the evening rush hour which will add extra time to the commute for anyone travelling home after the work day.

There could also be some lake enhancement off the southwestern shoreline of Lake Ontario boosting the potential snowfall rates over the Hamilton, Oakville and Grimsby regions. For Eastern and Central Ontario, the snow will start by the early afternoon with the heaviest snow occurring during the evening into the early morning hours of Thursday. Snow is expected to taper off by sunrise on Thursday, but flurries could linger into the afternoon, especially in Eastern Ontario.

As we are expected to remain on the cold side of this system, the expected snowfall totals are fairly straightforward compared to previous events where mixing led to inconsistent accumulation. However, there could be some marginal mixing around the Lake Ontario shoreline and into the Niagara region if temperatures can get warm enough.

A fairly large zone encompassing Eastern Ontario and parts of Central Ontario and the Golden Horseshoe is currently expected to see totals ranging from 15 to 25cm by Thursday afternoon. A few locations mainly in Eastern Ontario and around Hamilton with the lake enhancement could locally see up to 30cm, but those totals will be extremely isolated.

The rest of Southern Ontario including Southwestern Ontario and the Niagara region (where some mixing could occur) are currently looking at totals around 10 to 20cm. Believe it or not, the lower snowfall totals will be found in Northern Ontario with North Bay seeing around 5-10cm and Sudbury getting a few centimetres at most!

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Active Weather Continues Across Southern Ontario With Another Winter Storm on the Horizon to End the Week

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It sure appears that Mother Nature is making up for the lack of storms earlier in the season across Southern Ontario with yet another system set to bring messy weather over the next few days. The exact impact of this winter storm will vary depending on your location with those through Central and Eastern Ontario seeing mostly snow and ice pellets. While to the south, our focus will be on a prolonged risk of freezing rain for a wide swath of Southwestern Ontario and the GTA. There is even the risk of a non-severe thunderstorm around the Windsor and Chatham region late Thursday!

Impacts from this system will begin to be felt just after midnight tonight for Deep Southwestern Ontario coming in the form of rain. Rain will continue across this area with the potential for a non-severe thunderstorm in the evening. Total rainfall accumulation will range from 20-40mm although it might be higher should we see a thunderstorm.

As the bands of precipitation slowly spread to the northeast, it will encounter a layer of colder air locked in at the surface making for the perfect environment for freezing rain. An expansive area of freezing rain will develop across Woodstock, K/W, Guelph, Orangeville and parts of the GTA away from the shoreline during the mid to late morning hours on Thursday.

This is very temperature dependent and even just one degree could be the difference between significant freezing rain and normal rain. Those closest to the Lake Ontario and Huron shorelines will see slightly warmer temperatures allowing for a faster switchover to rain by the late morning. Away from the lakeshore, especially in the higher elevations of the Dundalk Highlands, the freezing rain could linger well into the afternoon leading to prolonged icing and potential power outages. The remaining regions throughout Southwestern Ontario and the GTA will see a transition over to rain by the late afternoon.

Total ice accretion is expected to max out at around a few millimetres along the shorelines which will be quickly melted away by the switchover to rain. Those in higher elevations including K/W, Guelph, Orangeville and Newmarket could see upwards of 6-12mm of icing throughout the day on Thursday. This amount of icing would certainly lead to icy road conditions and localized power outages. Travel isn’t recommended here until conditions improve later in the day and we will likely see school bus cancellations for Thursday.

Those in Central and Eastern Ontario will be on the cold side of this storm with ice pellets and heavy snow being the primary concern. Precipitation here will start sometime during the afternoon beginning as an ice pellet and snow mix with more snow further to the north along the Quebec border and Northeastern Ontario.

As the system progresses through the region late Thursday, we expect the southern parts of the aforementioned regions such as Barrie, Peterborough and Kingston to see some freezing rain mixing in with the ice pellets and snow. Freezing rain and drizzle may continue to pose an issue throughout the evening and into the overnight hours.

The highest snowfall totals will be found in Northeastern Ontario including Sudbury and North Bay which could see as much as 10-20cm by the end of Friday. General snowfall totals will range from 5 to 10cm across Central and Eastern Ontario with lower amounts to the south as more ice pellets and freezing rain mix in and reduce the potential accumulation.

As the system exits the region overnight and into Friday morning, we will see colder air flood in behind it. As a result, any remaining precipitation is expected to transition over to flurries by Friday morning. Light snow will continue to fall across Southern Ontario throughout the day on Friday, but we aren’t expecting any significant accumulation.

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Freezing Rain Risk Threatens to Disrupt the Tuesday Morning Commute Across Southern Ontario

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NOTE: You can click on the map to open a zoomable image which will be easier to read.

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The weather story across Southern Ontario throughout the weekend has been dominated by what most would consider as ‘perfect’ winter weather. While the temperature was colder than we’ve been used to this winter, it was accompanied by a rare sight - the sun! As we start the week, our attention will turn to the potential for freezing rain starting early Tuesday morning and lingering throughout the afternoon.

The overall severity of this freezing rain event is expected to be fairly minor with 2-4mm of ice accretion at most. However, the main concern will be because of the timing as it collides with the busy morning commute throughout the GTA. This is certainly enough ice to create slick driving conditions out on the roads, especially on untreated surfaces. As a result, expect travel delays on Tuesday and potentially even some school bus cancellations.

We will start to see patchy freezing rain move into our region just after midnight starting with Southwestern Ontario as it slowly progresses to the northeast. Locations such as London and parts of Grey-Bruce counties could see a few hours of freezing rain before switching over to rain. Those closest to the Lake Huron shoreline and the Windsor/Chatham region should remain above the freezing mark throughout this event.

By the mid-morning hour just before dawn, an expansive band of freezing rain is expected to stretch through Kitchener-Waterloo and across the GTA. Several hours of freezing rain lingering into the late morning hours is likely, especially in higher elevations like Guelph and Orangeville. Freezing rain will transition to rain by the noon hour with those closest to the shoreline such as Downtown Toronto seeing a quicker switchover. Total accretion of a few millimetres is possible away from the lakeshore.

The heaviest freezing rain is expected across southern parts of Central and Eastern Ontario including Barrie, Muskoka, Peterborough and Kingston. Freezing rain will start by the late morning with the worst conditions during the early afternoon. This is where we believe that some regions will pick up more than just a glazing of ice with up to 5mm of accretion possible. Those in the Ottawa Valley will see the freezing rain start later in the afternoon and lingering into the evening and will be overall lighter so accretion will remain under 2mm.

Precipitation will come to an end by the evening across Southern Ontario although scattered flurries may continue overnight into Wednesday as temperatures hover around the freezing mark. More messy weather is possible to end off the week on Thursday and Friday with another system bringing the risk of freezing rain and accumulating snow. More details on that in the coming days as we get closer.

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