January 12, 2025

Intense Snow Squalls Return to Parts of Southern Ontario on Monday; Possible Deep Freeze for Late January

January 12, 2025/ Brennen Perry

***NOTE: YOU CAN CLICK ON THE MAP TO OPEN A ZOOMABLE IMAGE***

⬇️ ZOOMED IN MAP CAN BE FOUND FURTHER DOWN ⬇️

The first half of January is almost behind us, and in Southern Ontario, the weather has shifted significantly compared to December. Colder temperatures have dominated, leading to several bouts of snow squall activity off Lake Huron and Georgian Bay. These events have primarily impacted regions southeast of the lakes.

The threat of snow squalls is set to return this week, with the heaviest snow expected east of Lake Huron and Georgian Bay. A predominant westerly flow will target areas such as Parry Sound, Bracebridge, Gravenhurst, and parts of Grey and Bruce counties. This pattern is reminiscent of what we experienced in early December, with heavy snow focused in the snowbelt regions east of Georgian Bay.

Snow squalls are forecasted to develop Monday afternoon and further intensify into the evening and overnight hours. Rapid snowfall accumulation and near-zero visibility are likely, especially late Monday into early Tuesday.

By the time the squall activity tapers off on Tuesday afternoon, some localized areas in the Muskoka and Parry Sound regions could see totals between 25 and 50 cm.

A brief reprieve from lake-effect snow is expected after Tuesday as milder air moves into Southern Ontario. However, another Arctic plunge is anticipated by early next week, potentially bringing some of the coldest air of the season.

Wind chills could make it feel like -30°C or even -40°C, especially in Central and Eastern Ontario!

This upcoming cold snap could also reignite intense lake-effect snow activity, with several rounds of squalls likely to impact the snowbelt regions throughout the rest of January.

BREAKING DOWN THE TIMING OF THE SQUALLS

Before the snow squalls begin Monday, a weak clipper system is forecasted to move across Southern Ontario late Sunday into early Monday morning. While this system will lack significant moisture, it may bring light snowfall of 2 to 5 cm in most areas, with localized pockets potentially reaching up to 5 cm.

**HOURLY SNOWFALL RATE/intensity** - MAP FROM WEATHERBELL

In the wake of the clipper, lake-effect snow is expected to ramp up east of Georgian Bay on Monday afternoon. Initially, the snow may be disorganized, spreading moderate to heavy snowfall across Muskoka and parts of Grey and Bruce counties.

By Monday evening, forecast models indicate the formation of a more organized snow squall. This band is expected to stretch from the Bruce Peninsula across Georgian Bay and inland between MacTier and Parry Sound.

The squall could remain stationary overnight, leading to rapid snowfall accumulation at rates of 5 to 10 cm per hour.

Model projections differ slightly regarding the exact placement of the most intense squall. The American model places the heaviest snow over Parry Sound, Pointe au Baril, Sprucedale, and Burk’s Falls.

Meanwhile, the Canadian model suggests the squall may shift south after midnight, targeting areas such as Port Carling, Rosseau, Port Sydney, and Bracebridge for the heaviest snowfall.

Both models agree that the squall will gradually sink southward by late Tuesday morning, bringing heavy snow to northern Simcoe County, including Midland and Orillia.

However, there is uncertainty about the intensity and duration of the squall as it moves further south into Barrie.

While Georgian Bay will see the most intense squalls, Lake Huron is also expected to generate less intense snow bands Monday evening into Tuesday morning. These bands could impact Owen Sound, Kincardine, and Hanover, with bursts of heavy snow.

As the wind shifts southward, areas like Goderich and London may briefly experience lake-effect snow Tuesday morning into the afternoon.

WHO COULD GET BURIED IN SNOW

As is typical with lake-effect snow, snowfall totals will vary widely depending on where the narrow bands persist. The highest accumulations are expected in Parry Sound, Rosseau, Port Carling, Port Sydney, Bracebridge, and Gravenhurst, where 25 to 50 cm of snow is possible by Tuesday afternoon.

In some areas, totals could exceed 50 cm if the squall remains stationary for an extended period.

Surrounding areas such as Midland, Washago, Coboconk, Minden, Huntsville, and Sprucedale may see snowfall totals of 15 to 25 cm.

The Grey-Bruce region, including Kincardine, Port Elgin, Wiarton, Lion’s Head, Tobermory, Owen Sound, Chatsworth, Hanover, and Meaford, is expected to receive 15 to 25 cm, with localized totals of 30 to 40 cm if squalls intensify.

Elsewhere in Central and Southwestern Ontario, snowfall amounts will range from 5 to 15 cm, combining accumulation from the weak clipper system and lake-effect snow. Most areas will see closer to 5 cm, with lake-effect zones reaching 10 to 15 cm.

Less than 5 cm is expected for the rest of Southern Ontario.

SNOW SQUALL WATCH ISSUED BY ENVIRONMENT CANADA

CURRENT ENVIRONMENT CANADA ALERTS AS OF SUNDAY EVENING

Environment Canada has issued snow squall watches for areas around Lake Huron, Georgian Bay, and Lake Superior.

The highest totals in these watches match our forecast, with 20 to 40 cm expected for Parry Sound and Muskoka and 15 to 25 cm for the Grey-Bruce region.

Northern Ontario, including Sault Ste. Marie and Manitoulin Island could see localized snowfall of 10 to 20 cm from Monday evening into Tuesday morning.

LOOKING AHEAD TO THE REST OF JANUARY

The persistence of lake-effect snow this far into January may seem unusual, but the Great Lakes remain relatively ice-free and warmer than usual due to a mild fall and warm start to winter. This provides ample moisture for snow squalls when Arctic air moves in.

**ICE COVERAGE MAP AS OF JANUARY 11, 2025** - source: NOAA

Colder weather in recent weeks has helped cool the lakes and increased ice coverage, particularly in shallower areas like Lake Erie and the shorelines of Lake Huron and Georgian Bay.

Ice coverage has risen from 1% at the start of January to over 10% as of January 11.

**TEMPERATURE ANOMALY** - MAP FROM WEATHERBELL

Looking ahead, a significant Arctic blast is expected during the January 20–24 period, with temperatures 10 to 20 degrees below seasonal norms across much of Southern Canada and the northern U.S.

Southern Ontario could experience lows well below -20°C, potentially nearing -30°C in some areas. Wind chills could make it feel as cold as -35°C to -40°C, particularly in Central and Eastern Ontario.

This intense cold will likely bring additional snow squalls and accelerate ice formation on the Great Lakes. If current trends continue, lake-effect snow activity could diminish significantly by the end of the month as ice coverage increases, shutting off the moisture source for squalls.

For snowbelt residents weary of lake-effect snow, relief may finally be on the horizon!

January 09, 2025

Widespread Snowfall to End the Week Across Southern Ontario on Friday; Up to 5-10cm Possible

January 09, 2025/ Brennen Perry

While 2025 began with heavy snow across parts of Southern Ontario, most of the activity so far has been confined to traditional snowbelt regions. That’s about to change, as a new system is set to bring the first widespread snowfall of the year to much of Southern Ontario starting Friday.

Most of Southwestern, Central, and Eastern Ontario can expect snowfall totals of 5 to 10 cm between Friday afternoon and Saturday morning. However, areas along the Lake Huron shoreline and into the Bruce Peninsula may see enhanced snowfall, with totals reaching 10 to 20 cm due to lake-effect activity and embedded snow squalls.

As the system moves out, additional snowfall is likely over the weekend. Lake-effect snow squalls developing southeast of Lake Huron and Georgian Bay could bring localized accumulations of 20 to 30 cm from Saturday afternoon into Sunday.

SNOWFALL TIMING

**PRECIPITATION TYPE** - MAP FROM WEATHERBELL

The system-related snowfall will begin spreading into Southwestern Ontario late Friday afternoon, with regions near Lake Huron, including Deep Southwestern Ontario, seeing snow first.

Through the dinner hours, the snow will advance northeast, gradually reaching the Golden Horseshoe and portions of Central Ontario by Friday evening. By midnight, snow will cover most of Southern Ontario, extending into Eastern Ontario.

The most intense period of snowfall is expected overnight Friday into early Saturday morning. While the snow will generally be light, it could lead to several hours of steady accumulation, potentially impacting travel.

Exercise caution if you plan to drive during this time, and remember to adjust your speed to match road conditions.

For areas along the Lake Huron shoreline and into the Bruce Peninsula, lake-enhanced snowfall could intensify during the evening and overnight hours on Friday, resulting in heavier accumulations compared to surrounding areas.

Snowfall from this system will taper off from west to east starting early Saturday morning in Southwestern Ontario, with Eastern Ontario holding onto snow until late morning.

Flurries may linger into Saturday afternoon, especially in some regions.

As the system exits, lake-effect snow squalls may develop off Lake Huron and Georgian Bay by Saturday afternoon. Forecast models currently show some uncertainty about how organized these squalls will be and whether they will lock into specific areas for prolonged periods.

Higher-resolution models are just coming into range, so a detailed forecast for snow squall activity will be issued on Friday.

HOW MUCH SNOW TO EXPECT

In terms of totals, most of Southern Ontario will see 4 to 8 cm of snowfall, with slightly higher amounts of up to 10 cm possible in localized areas. This includes the east end of the Greater Toronto Area (GTA), such as Oshawa, and parts of Southwestern Ontario due to minor lake enhancement from Lake Ontario and Lake Huron.

The Golden Horseshoe and Ottawa Valley are expected to see slightly lower snowfall amounts, closer to 3 to 6 cm.

A zone along the Lake Huron shoreline—including Grand Bend, Goderich, Kincardine, and the Bruce Peninsula—could see locally higher accumulations by Sunday afternoon. Current estimates suggest 10 to 15 cm for these areas, with up to 20 cm possible for the Bruce Peninsula.

WEEKEND SNOW SQUALL PREVIEW

Environment Canada has identified areas near Barrie, Goderich, and London as hotspots for the most intense snow squalls over the weekend.

Here’s Environment Canada’s weekend outlook:

Saturday, January 11, 2025: “Lake effect snow squalls off Lake Huron and Georgian Bay are expected to develop Saturday afternoon. Local snowfall amounts of 10 to 15 cm are possible along with reduced visibility in heavy snow.”
Sunday, January 12, 2025: “Lake effect snow squalls off Lake Huron and Georgian Bay are expected to continue on Sunday. Local snowfall amounts of 10 to 15 cm are possible along with reduced visibility in heavy snow.”

As always, stay tuned for updates, especially if you’re in areas likely to experience lake-effect snow. Stay safe, and plan ahead for winter driving conditions!

January 07, 2025

Mid-Week Squalls Could Dump Up to 25-50cm of Snow to Parts of Southwestern Ontario by Thursday

January 07, 2025/ Brennen Perry

The New Year has certainly started on a frigid note across Ontario, as Arctic air has firmly settled over the region in recent days. These cold temperatures, combined with open lakes, have created the perfect conditions for lake-effect snow. Late last week and into the weekend, parts of the province experienced significant snowfall, with totals southeast of Georgian Bay reaching or exceeding 50 cm.

Over the past 24 hours, the lake-effect machine has largely taken a break, aside from some minor activity south of Lake Huron and Georgian Bay. However, that respite will be short-lived. Beginning Tuesday evening, snow squalls are expected to return with a vengeance as wind directions realign and even colder air moves into the region. These squalls are anticipated to persist through Wednesday and into early Thursday before tapering off.

This round of lake-effect snow will likely target areas that were largely spared during the last event. The focus this time will be on regions southeast of Lake Huron and along the southern shoreline of Georgian Bay. Some of the hardest-hit areas could include London and Collingwood, with snowfall totals potentially ranging from 25 to 50 cm over the next 48 hours.

As for the timing, models differ slightly on the intensity and precise placement of the squalls. The latest data suggests snow squalls could begin organizing as early as Tuesday evening. The squall off Georgian Bay is expected to impact the Collingwood and Blue Mountain area, stretching inland toward Creemore, Alliston, and Shelburne. It may also affect the Highway 400 corridor just south of Barrie.

Meanwhile, activity off Lake Huron could produce multiple squalls developing between Kincardine and Grand Bend, with bands extending inland in a southeasterly direction. This puts portions of Huron, Perth, and Middlesex counties in the crosshairs.

The Georgian Bay squall appears to be somewhat weaker than its Lake Huron counterpart, likely due to the smaller lake surface area supplying moisture. That said, it is expected to remain relatively stationary through the overnight hours into Wednesday, resulting in steady snowfall accumulation and reduced visibility.

Travel in this area will likely be challenging from Tuesday night into Wednesday, with little improvement expected until the activity begins to subside overnight.

Lake Huron squalls, on the other hand, are expected to shift around more frequently, spreading out snowfall accumulations. By Wednesday morning, the primary squall is forecasted to come ashore around Grand Bend, extending inland toward Lucan, Strathroy, and London.

There is still some uncertainty about whether the squall will directly impact the City of London or remain just northwest. Western parts of the city are likely to see the heaviest snowfall, while eastern areas may receive lighter accumulations.

Scattered snow squalls east of Lake Huron are expected to continue affecting Huron and Perth counties throughout Wednesday. These squalls may vary in intensity, and if one becomes particularly organized and stalls over an area, rapid snowfall accumulation could occur.

The most intense conditions are expected during the day on Wednesday, extending into the evening and overnight hours.

By midnight, the lake-effect activity is expected to become more localized. The Georgian Bay squall will likely retreat closer to the shoreline, while the Lake Huron squalls may consolidate into a narrower band near Grand Bend, extending into the London area.

While this will reduce the overall impact, areas caught under these more focused squalls could experience increased snowfall rates for several hours overnight into early Thursday morning.

By pre-dawn Thursday, the lake-effect activity is anticipated to taper off, with the Georgian Bay squall dissipating before sunrise and the Lake Huron squall following a few hours later.

Snowfall totals from this round of snow squalls will vary widely, as is typical with these events. This forecast is particularly tricky due to discrepancies in model data regarding the intensity of the snow bands, which will significantly affect accumulation.

Based on the current environment and dynamics, there is potential for 25 to 50 cm of snow in areas such as London, Lucan, Grand Bend, Clinton, and Collingwood. However, these totals are not guaranteed, as exact amounts will depend on where the bands set up.

For London, in particular, snowfall accumulations will likely be heavier in the northwest, while eastern areas may only see totals between 10 and 25 cm.

Surrounding areas like Goderich, Point Clark, Mitchell, Strathroy, and St. Thomas could see localized accumulations of 15 to 25 cm, depending on the positioning of the bands. Similarly, areas southwest of Barrie, including Angus, Alliston, and Beeton, may receive 10 to 20 cm as the Georgian Bay squall extends inland.

Outside these regions, significant snowfall is not expected due to the highly localized nature of lake-effect activity. However, portions of Eastern Ontario near the U.S. border and areas east of Ottawa may see 5 to 10 cm of accumulation on Wednesday due to a separate system lingering over Quebec.

January 03, 2025

Snow Squall Blast Continues This Weekend as Parts of Southern Ontario Could See an Additional 25-50cm of Snow

January 03, 2025/ Brennen Perry

The New Year has certainly started on a snowy note for parts of Ontario's snowbelt regions. A multi-day snow squall event is underway around Lake Huron and Georgian Bay, with some areas already receiving over 50 cm of snow. Locations east of Lake Huron, Simcoe County, and parts of Kawartha Lakes have been among the hardest hit so far.

While the activity off Georgian Bay weakened somewhat on Friday evening, it's expected to ramp up again by Saturday afternoon and continue through Sunday. Snow squalls will also persist east of Lake Huron Friday night into Sunday, though the bands will shift around multiple times during this period.

By the end of the weekend, some areas could see an additional 25 to 50 cm of snow, with localized totals reaching as high as 75 cm. Combined with the snow that has already fallen, totals in the hardest-hit regions could exceed one meter (100 cm). This includes parts of Simcoe County, where 50 to 75 cm of snow has already accumulated over the past two days.

As of Friday evening, multiple discrete squalls off Lake Huron are bringing heavy snow to areas stretching from Bayfield to Kincardine and as far inland as Woodstock, Kitchener, and Guelph. This activity is expected to continue through the night, with southern squalls gradually merging northward by early Saturday morning.

The New Year has certainly started on a snowy note for parts of Ontario's snowbelt regions. A multi-day snow squall event is underway around Lake Huron and Georgian Bay, with some areas already receiving over 50 cm of snow. Locations east of Lake Huron, Simcoe County, and parts of Kawartha Lakes have been among the hardest hit so far.

While the activity off Georgian Bay weakened somewhat on Friday evening, it's expected to ramp up again by Saturday afternoon and continue through Sunday. Snow squalls will also persist east of Lake Huron Friday night into Sunday, though the bands will shift around multiple times during this period.

By the end of the weekend, some areas could see an additional 25 to 50 cm of snow, with localized totals reaching as high as 75 cm. Combined with the snow that has already fallen, totals in the hardest-hit regions could exceed one meter (100 cm). This includes parts of Simcoe County, where 50 to 75 cm of snow has already accumulated over the past two days.

As of Friday evening, multiple discrete squalls off Lake Huron are bringing heavy snow to areas stretching from Bayfield to Kincardine and as far inland as Woodstock, Kitchener, and Guelph. This activity is expected to continue through the night, with southern squalls gradually merging northward by early Saturday morning.

By Saturday morning, an intense squall is expected to form between Sauble Beach and Kincardine, extending inland to areas such as Hanover, Dundalk, and Orangeville. This band may stretch as far east as the western GTA, including Mississauga and Brampton.

While overall accumulations in the GTA should remain around 5 cm or less, these squalls could still lead to near-zero visibility and hazardous travel conditions due to blowing snow.

For Georgian Bay, lingering lake-effect activity will continue Friday night into Saturday morning, though no significant squalls are expected until later in the day.

By mid to late Saturday afternoon, the Lake Huron squall is expected to shift northward as wind directions change. This will allow it to cross over the southern Bruce Peninsula and connect with Georgian Bay, bringing heavy snowfall to Simcoe County, particularly in the Barrie-Orillia corridor.

This squall may also extend into parts of northern York and Durham regions, as well as the Kawartha Lakes region.

As seen earlier in this event, the squall is expected to lock in place, leading to intense snowfall rates of 5 to 10 cm per hour late Saturday through Sunday. Driving conditions will deteriorate rapidly, and non-essential travel should be avoided due to the potential for road and highway closures.

By late Sunday morning, the Georgian Bay squall is expected to sink southward, bringing an end to the snow for areas southeast of the bay. Moderate to heavy lake-effect snow may persist in parts of Grey and Bruce counties throughout Sunday, with activity finally tapering off overnight into Monday morning.

The heaviest snowfall totals are expected in areas such as Wiarton, Owen Sound, Kincardine, Hanover, Meaford, Collingwood, Wasaga Beach, Midland, Barrie, Orillia, and Beaverton. These regions could see an additional 25 to 50 cm of snow by the end of the weekend, depending on the squall locations.

Surrounding areas, including Goderich, Woodstock, Stratford, Kitchener, Guelph, Angus, Bradford, Lindsay, and Port Perry, may also see significant snowfall if the squalls align. These areas could receive 15 to 25 cm of snow, though amounts will vary widely due to the localized nature of snow squalls. Our forecast is intentionally broad to account for potential shifts in squall placement.

Snowfall amounts will drop off quickly outside the snowbelt regions. However, parts of the northern and western GTA could see 5 to 10 cm, with isolated amounts up to 15 cm. Even Toronto might get a few centimeters of brief, heavy snow as the bands shift inland.

Eastern and Deep Southwestern Ontario are not expected to see any significant snowfall from this event.

January 01, 2025

Snowy Start to 2025 in Ontario’s Snowbelt; Squalls Could Deliver Up to 50cm of Snow by End of Week

January 01, 2025/ Brennen Perry

As we kick off the New Year across Ontario, we’re starting off with a blast of cold Arctic air that moved into the region over the past 24 hours. With this chilly air comes the inevitable return of lake-effect snow in the traditional snowbelt areas surrounding Lake Huron, Georgian Bay, and Lake Superior.

Strong snow squalls are anticipated to develop Wednesday evening and are likely to persist through Thursday and into Friday. These squalls are expected to bring intense snowfall rates of 5-10 cm per hour, along with near-zero visibility that will make travel nearly impossible in the hardest-hit areas.

The main focus for this lake effect activity will be in parts of Huron, Perth, Grey, Bruce, and Simcoe counties. Depending on where these narrow snow bands establish, localized accumulations could approach or exceed 50 cm by week’s end, with additional snowfall possible through the weekend as the lake effect machine remains active.

Disorganized squalls are expected to begin forming off Lake Huron and Georgian Bay late Wednesday evening or around midnight. According to the latest data, multiple bands could develop off Lake Huron, with one possibly targeting areas south of Owen Sound.

Another band may stretch from Goderich inland towards Stratford and St. Marys, just north of London. However, there remains some uncertainty about where exactly these squalls will set up, which will determine the heaviest snowfall locations.

For Georgian Bay, models show differing timelines. One suggests squall activity could begin just after midnight, while another predicts development near sunrise on Thursday. If squalls form, areas like Wasaga Beach and Barrie could be affected overnight.

Overnight, the bands that do form may shift around and dissipate periodically, spreading snowfall over a broader area. If a squall locks into place unexpectedly, snowfall can accumulate rapidly in a short time.

The event is expected to intensify by mid to late Thursday morning as the northern squall off Lake Huron drifts northward, potentially crossing the Bruce Peninsula and reconnecting over Georgian Bay. This setup could lead to a rare "multi-lake connection," allowing the squall to draw moisture from a long stretch of open water.

The result would be heavy snowfall affecting areas such as Owen Sound, Collingwood, Wasaga Beach, and Barrie, with possible extensions into Durham Region and southern Kawartha Lakes.

Another squall off Lake Huron could extend inland into Huron and Perth counties, with potential impacts as far as Kitchener-Waterloo. While intense snowfall could occur, squalls are notoriously narrow, and not all areas will be directly affected.

By late Thursday afternoon, snow squalls off Lake Huron may weaken as the wind shifts more westerly, reducing the available lake surface from which the squalls can pull moisture. The Georgian Bay squall, however, could continue intensifying and shift northward, potentially impacting areas like Midland and Orillia while giving Barrie a break.

There remains uncertainty regarding the squall's position, with some models suggesting it may remain south of Orillia. If the squall locks in place overnight, areas such as Simcoe County and southern Kawartha Lakes could see prolonged periods of heavy snow, leading to extremely poor travel conditions, potential road closures, and significant snowfall accumulations.

By late Friday morning, shifting winds are expected to push the Georgian Bay squall southward, potentially dissipating it by midday. However, lake effect activity off Lake Huron may persist southeast of the lake into areas like Kitchener and London through Friday afternoon and evening.

The hardest-hit regions from this event will likely include Grey-Bruce and southern and central Simcoe County, including Wasaga Beach and Barrie. Snowfall totals in these areas could range from 25 to 50 cm by Friday night.

Some localized spots, particularly between Barrie and Orillia, may see totals exceeding 50 cm, with the potential for as much as 75 to 100 cm. However, model disagreement prevents us from confidently forecasting such extreme totals.

It’s important to note that snow squalls are highly localized phenomena, often only a few kilometres wide. While our forecasts aim to highlight the most likely zones, the reality is that squalls can shift unexpectedly, meaning not every location in a forecasted zone will see the same impacts.

Surrounding areas, including Orillia, Lindsay, Fenelon Falls, and Port Perry, could see localized snowfall of 15-25 cm from the Georgian Bay squall, with totals tapering quickly outside of this zone. Peterborough and areas along the Lake Ontario shoreline between Oshawa and Brighton may see 5-15 cm.

For regions east of Lake Huron, a narrow band from Goderich to Wingham and Listowel could see 25-50 cm of snow, with some extension into Kitchener, where totals may approach 15-20 cm. However, the exact setup will depend on the squall’s inland reach.

Elsewhere, the Golden Horseshoe could see a few centimeters of snow from brief, heavy bursts of lake effect activity, but no significant accumulations are expected. Areas north of Bracebridge, east of Peterborough, and south of Woodstock are likely to see little to no snow.

As always, lake effect snow forecasts carry inherent uncertainty. While many areas may receive less snow than forecasted, those directly in the path of these intense squalls could see the full brunt of the snowfall. Be prepared for rapidly changing conditions, and avoid non-essential travel in the hardest-hit zones.

Snow squalls are also expected to affect regions east and southeast of Lake Superior in Northern Ontario starting Wednesday evening. These squalls will continue to persist throughout the day on Thursday before shifting south of the border.

The Sault Ste. Marie region appears to be in the bullseye and could see localized snowfall totals between 25 to 50cm by the time the snow tapers off late Thursday.

December 20, 2024

Pre-Christmas Squalls Could Bring Up to 25-50cm of Snow on Saturday to Parts of Southwestern Ontario

December 20, 2024/ Brennen Perry

As we approach the final weekend before Christmas, Southern Ontario is gearing up for the coldest air of the season so far. With the lakes still unfrozen after the unseasonably mild fall, conditions are setting up perfectly for the lake effect snow machine to roar back to life, particularly off Lake Huron.

Lake effect snow squalls are expected to develop as early as Friday evening along the southern shoreline of Lake Huron and persist through much of Saturday. Current indications suggest the heaviest snowfall will target the corridor between Sarnia and Strathroy. By the time the squalls taper off late Saturday, some areas could be buried under 25 to 50 cm of fresh snow.

This snowfall is promising news for those hoping for a White Christmas. With below-freezing temperatures expected to last through Tuesday, the snow should be deep enough to hold on despite a brief warm-up on Christmas Eve into Christmas Day when temperatures may climb above freezing.

Based on the latest data, a fairly intense snow squall is anticipated to form around midnight, likely affecting areas between Petrolia and Strathroy. However, the exact location of this band remains uncertain and will determine which areas see the most significant snow. The best bet at this time places the heaviest snow over Port Franks, Lambton Shores, and Kettle Point.

The squall is expected to persist through the overnight hours into early Saturday morning, bringing dangerous travel conditions in the affected regions. Rapidly accumulating snow combined with near-zero visibility will likely lead to road and highway closures. There’s also potential for the squall to extend further inland, possibly reaching areas northeast of Chatham along the Lake Erie shoreline.

Meanwhile, locations along the eastern shoreline of Lake Huron, from Kincardine to Grand Bend, may experience occasional bursts of heavy snow as the squall shifts and clips the shoreline.

By late Saturday morning and into the afternoon, the lake effect activity south of Lake Huron is expected to weaken as the band becomes more spread out and less organized. The squall should gradually diminish and retreat closer to the shoreline by Saturday evening, eventually fizzling out overnight into early Sunday morning.

In addition to the Lake Huron squalls, minor lake effect activity is possible south of Georgian Bay, including areas like Owen Sound, Meaford, and Collingwood. However, this activity is not expected to be as intense, with light to moderate snowfall likely throughout the day on Saturday.

When it comes to snowfall accumulation, variability is the nature of lake effect events. Narrow squalls can lock into a region and dump significant snow over a small area while sparing nearby locations.

We currently expect areas including Warwick, Watford, Forest, and Lambton Shores to receive between 25 to 50 cm of snow by the end of Saturday, with localized totals possibly exceeding 50 cm in some spots, although this is likely an overestimate.

The gradient will be sharp, with Petrolia and Grand Bend potentially seeing 15 to 25 cm. Sarnia and Strathroy, on the outskirts of the main activity, are likely to receive just 2 to 5 cm, although even a slight shift in the squall’s position could put these areas into the heavier snow zone.

Further up the eastern Lake Huron shoreline, locations from Kincardine to Grand Bend could see 5 to 15 cm of snow, with most areas leaning toward the lower end of that range.

South of Georgian Bay, including Owen Sound, Meaford, and Collingwood, snowfall is expected to range between 2 to 5 cm, with localized amounts up to 10 cm possible if the activity becomes more organized.

Elsewhere, the Niagara Region could pick up 2 to 5 cm of snow overnight into early Saturday morning as lingering precipitation from a previous system continues.

For the rest of Southern Ontario, no significant snowfall is expected this weekend. However, we are closely monitoring a potential snowmaker early next week between Monday and Tuesday, which has been trending stronger in recent model data. This system could bring heavy snow to parts of Southern Ontario, maybe sealing the deal on a White Christmas for many. We’ll provide more details on that in a separate forecast.

December 11, 2024

Return of Squalls to Ontario’s Snowbelt This Week With Blizzard Conditions & Over 50cm of Snow Possible

December 11, 2024/ Brennen Perry

While the brief break from lake-effect snow earlier this month brought milder air and rain to the snowbelt regions, the respite appears to be short-lived.

Snow squall activity is expected to make a comeback as we approach the end of the week. With multiple days of snow squalls anticipated, we could once again see impressive snowfall totals, rivaling those from earlier this month.

Colder air will begin to filter into Southern Ontario from the northwest late Wednesday afternoon, dropping temperatures below freezing through the evening. This influx of cold air will trigger the development of lake-effect snow bands, with ideal conditions persisting through Thursday and into Friday.

Current projections suggest two primary zones will bear the brunt of the snow squalls: one east of Lake Huron and the other southeast of Georgian Bay. The Lake Huron squall is expected to impact southern portions of Grey and Bruce counties, including Owen Sound, Chatsworth, and Meaford. Meanwhile, the Georgian Bay squall will likely target central Simcoe County, extending northward into southern Muskoka.

Snowfall totals in the hardest-hit areas could exceed 50 cm, with the possibility of approaching the staggering 100 cm seen in Bracebridge and Gravenhurst earlier this month. Whether such totals materialize depends on whether any of the snow squall bands remain stationary for extended periods.

To make matters worse, strong winds are expected to develop late Wednesday and persist into Thursday morning. Gusts could reach 60–80 km/h, particularly in Grey-Bruce and Simcoe County, significantly reducing visibility and creating hazardous travel conditions.

Blizzard conditions may develop, and travel is strongly discouraged during this timeframe. School bus cancellations are almost certain along the Lake Huron and Georgian Bay shorelines on Thursday.

The lake-effect snow is expected to begin late Wednesday afternoon, with the first band forming off Lake Huron. Initially driven by northwesterly winds, this band will target areas near Goderich before shifting northward as winds veer to a more westerly direction by evening.

By midnight, the main Lake Huron squall is expected to become stationary, affecting areas from Wiarton southward to Port Elgin, Owen Sound, and Meaford. Simultaneously, snow bands will begin forming off Georgian Bay, initially targeting Wasaga Beach, Midland, and Orillia. These may briefly lift northward Thursday morning, potentially reaching Gravenhurst and Bracebridge.

The most intense conditions are forecast for late Thursday morning into the afternoon. Two main corridors of concern are expected: Owen Sound to Collingwood off Lake Huron, and Wasaga Beach to Orillia off Georgian Bay. Snowfall rates will be exceptionally high, and the squalls could remain locked in place for 6–12 hours, leading to rapid accumulation.

Strong wind gusts during this period could result in blizzard conditions, with near-zero visibility on roads. Road and highway closures are likely in the hardest-hit areas, especially on Thursday.

By late Thursday night, the snow squalls may shift into the Bruce Peninsula and Muskoka regions. While the bands are expected to weaken by Friday morning, lingering activity could still produce scattered flurries before tapering off completely by the afternoon.

As with previous lake-effect events, it’s important to remember that these snow squalls are highly localized. Narrow bands of snow, often only a few kilometres wide, can result in dramatically different conditions over short distances. One location might see over 50 cm of snow while areas just a few kilometres away remain relatively unscathed.

We currently have high confidence in two zones being hardest hit: southern portions of the Bruce Peninsula, including Owen Sound, Chatsworth, Meaford, and Flesherton, and areas west of Orillia, including Midland and Coldwater. Accumulations in these regions could exceed 50 cm, with totals potentially nearing 100 cm if squalls remain stationary long enough. A more conservative estimate is 50–75 cm.

A wider swath of Grey-Bruce, including Kincardine, Port Elgin, Hanover, Lion’s Head, and Tobermory, as well as much of Simcoe County and northern portions of Kawartha Lakes, Gravenhurst, and Beaverton, could see 25–50 cm. Not all areas in this zone will hit these totals, as much depends on the placement and movement of the snow bands.

Further south and away from the snowbelt, accumulation decreases rapidly. Barrie itself may largely miss the snow, although it could see up to 25 cm if the bands shift slightly. The Georgian Bay squall may extend inland at times, bringing heavy snow to Lindsay and Peterborough, with 10–20 cm possible in these areas.

For regions in other parts of the snowbelt, including Muskoka, Parry Sound, Haliburton, and parts of Dufferin, Wellington, Perth, and Huron counties, totals are expected to range from 10–20 cm. The Golden Horseshoe, including London, Kitchener, and Guelph, will likely see only light flurries, with less than 5 cm expected.

December 05, 2024

London Area Could Get Hammered by Intense Snow Squall on Thursday With Locally Up to 50-75cm of Snow

December 05, 2024/ Brennen Perry

As the Alberta Clipper that brought widespread snowfall to Southern Ontario exits late Wednesday, snow squalls are set to return to the snowbelt regions. Unfortunately, the areas that were buried earlier this week will once again bear the brunt of this lake effect activity.

Locations just north and west of London appear to be in the bullseye, with the potential for 50 to 75 cm of fresh snowfall accumulation by the end of Thursday.

Lake effect activity is expected to begin organizing overnight and into early Thursday morning along the southern shorelines of Lake Huron and Georgian Bay. Current forecasts suggest this activity will consolidate into a few well-defined snow squalls by late morning or early afternoon.

The most intense squall is projected to form off the southeastern shoreline of Lake Huron, extending from Port Franks through Strathroy and into the west end of London. Additional streamers could impact areas further inland and along the eastern Lake Huron shoreline, stretching from Kincardine down to Grand Bend.

A separate squall will develop off Georgian Bay, spanning from Collingwood to Shelburne. Forecast models differ on the intensity of this squall, with some suggesting it could push far inland, potentially reaching parts of the Greater Toronto Area (GTA) just in time for the evening commute.

This scenario could bring a heavy burst of snow to the Hwy 400 corridor between Bradford and Vaughan, possibly extending to Mississauga and even the western parts of Toronto.

The primary concern with this event is that the squalls are unlikely to shift much throughout the day. Instead, they could remain stationary for over 12 hours, beginning Thursday morning and continuing into the late evening.

As seen in Muskoka over the weekend, stationary squalls can produce extreme snowfall rates of 10–15 cm per hour, quickly overwhelming plowing operations and making travel nearly impossible as highways are buried in snow.

Travel is strongly discouraged along the Lake Huron shoreline, particularly on Hwy 402 between London and Wyoming, during the day on Thursday and into the evening. Blizzard-like conditions, combined with rapid snowfall accumulation, will create dangerous and potentially life-threatening travel conditions.

The Georgian Bay squall is expected to diminish just after midnight, while the Lake Huron squall will gradually lift north of London during the pre-dawn hours on Friday. Additional lake effect snow is possible east of Lake Huron and Georgian Bay on Friday, though it remains unclear whether it will organize into significant squalls. We will provide updates in a separate forecast if substantial accumulation seems likely.

The most intense snowfall is expected to target a small area west of London, including Parkhill, Ailsa Craig, and Strathroy, where totals could exceed 50 cm and potentially reach 75 cm. It’s important to note that these higher totals will be very localized, as the squall is forecast to be quite narrow. The exact location of the heaviest accumulation will depend on where the squall sets up.

While the City of London is likely to avoid the worst of the snowfall, it isn’t entirely in the clear. The city’s west end could see totals ranging from 25 to 50 cm. A slight eastward shift in the squall could place London directly in its path, significantly increasing snowfall totals for the area.

Lower amounts are expected in London’s east end, which is likely to see between 10 and 20 cm. St. Thomas could also be affected, with snowfall potentially reaching 20–30 cm depending on how far inland the squall extends.

Other communities along the southeastern shoreline of Lake Huron, including Grand Bend, Lucan, Exeter, Clinton, and Goderich, are projected to receive 25–50 cm by the time the squalls diminish on Friday morning.

As is typical with snow squalls, snowfall gradients will be extremely sharp, and accumulation will drop off quickly outside the most affected areas. Locations such as Kincardine, Listowel, and Mitchell can expect totals of around 10–20 cm.

The Georgian Bay squall is anticipated to be less intense than its Lake Huron counterpart. Accumulations of 15–25 cm are expected for areas like Collingwood and Shelburne. If the squall extends into parts of the GTA, it could bring a quick 5–10 cm of snow, primarily affecting Brampton, Mississauga, and other areas in the western GTA.

Less than 5cm is expected for the rest of Southern Ontario.

December 03, 2024

Alberta Clipper to Bring a Snowy Blast to Southern Ontario on Wednesday With Up to 20cm Possible; Snowbelt Region Could See Up to 50cm

December 03, 2024/ Brennen Perry

The snowy landscape across Southern Ontario is quickly transforming as a multi-day snow squall event has blanketed parts of the snowbelt regions with over 100 cm of snow.

While the intense accumulation has primarily impacted areas around Lake Huron and Georgian Bay, the rest of Southern Ontario will soon have their turn as a weather system moves into the region on Wednesday.

This system-related snowfall will likely combine with lake enhancement and embedded snow squalls, resulting in higher accumulations in the snowbelt areas that are still digging out from the weekend’s relentless snowfall.

By Thursday morning, some snowbelt regions could see an additional 30-50 cm of snow. Meanwhile, a general 5-15 cm of snow is expected across much of Southern Ontario, including parts of the Greater Toronto Area (GTA), which has experienced minimal snowfall so far this season.

The Alberta clipper responsible for this system began pushing into Northwestern Ontario from Manitoba on Tuesday afternoon. Moderate to heavy snow will continue spreading across Northern Ontario through the evening and overnight.

In Northern Ontario, we expected the highest snowfall totals to be found east of Lake Superior stretching from Wawa down to Sault Ste. Marie. Snowfall totals of between 30 to 50cm are possible thanks to the system-related snowfall and snow squalls off Lake Superior.

Other areas around the Georgian Bay shoreline extending into Sudbury could be looking at around 20cm of snowfall accumulation. This will also be the case south of Lake Nipigon which could see some lake enhancement between Thunder Bay and Geardton.

The rest of Northeastern Ontario is looking at around 10 to 15cm with locally up to 20cm. Less than 10cm is expected for Northwestern Ontario including Thunder Bay.

Ahead of the system, lake effect snow has already started to intensify, beginning with Lake Superior on Tuesday afternoon. By Tuesday evening, snow squalls are expected to organize off Lake Huron and Georgian Bay, primarily targeting the Bruce Peninsula and areas northeast of Georgian Bay, such as Parry Sound, Britt, and North Bay. These snow squalls are likely to persist through the night into Wednesday morning.

Additional lake effect snow could develop off Lake Erie and Lake Ontario during the early morning hours of Wednesday, potentially drifting into the southern Niagara region and Prince Edward County. While this activity may cause reduced visibility and locally heavy snowfall, the squalls are not expected to remain stationary for long, limiting overall accumulation.

As the system reaches Southern Ontario around sunrise on Wednesday, the existing lake effect snow bands are expected to merge with the system’s light to moderate snowfall. This merging could enhance snow totals, particularly off the northern shorelines of Lake Erie and Lake Ontario. Narrow bands of heavy snow could stretch across the Niagara region and into parts of Central and Eastern Ontario, leading to significant variations in snowfall accumulations.

Snow totals will likely vary substantially due to localized banding caused by lake enhancement. Some areas may see only 5 cm, while nearby locations could receive 15-20 cm, depending on where the snow bands develop.

Another key factor with this system will be strong wind gusts, ranging from 50-70 km/h across Southern Ontario, beginning Wednesday morning and continuing throughout the day. These winds, combined with steady snowfall, could create blowing snow and reduced visibility, making travel hazardous. With this being the first significant snowfall event of the season outside the snowbelt, drivers are urged to exercise caution.

While the system is expected to exit Southern Ontario by late Wednesday, snow squall activity will persist off Lake Huron and Georgian Bay. An intense squall is projected to develop off Georgian Bay late Wednesday evening, stretching inland toward Midland, Orillia, and Gravenhurst, and continuing into the early hours of Thursday.

By Thursday morning, shifting winds will push the Georgian Bay squall southward toward Collingwood and Angus. This squall may extend far inland at times, impacting the Highway 400 corridor between Vaughan and Barrie, as well as parts of the northern GTA. Meanwhile, a Lake Huron squall is anticipated to stretch from Goderich through Grand Bend and into the London area.

Significant snowfall could occur on Thursday if these squalls remain stationary for an extended period. Current models suggest they may not weaken until late Thursday night or early Friday morning, potentially producing intense snowfall rates for over 24 hours.

Regarding snowfall totals, the uneven distribution caused by lake enhancement means localized accumulations will vary widely. The highest confidence lies in regions northeast of Georgian Bay, including Parry Sound, Sundridge, Britt, and North Bay, where 30-50 cm of snow is expected, with localized amounts possibly exceeding those totals due to snow squalls.

Surrounding areas, such as Muskoka and Orillia, could see 20-30 cm of snow by Thursday morning, accounting for system snow, lake enhancement, and snow squall activity. Similarly, areas east of Lake Huron could see totals ranging from 20-30 cm.

In Central and Eastern Ontario, widespread snowfall is likely to range from 10-15 cm, except for the Ottawa Valley, where accumulations may be closer to 5 cm. Lake enhancement could push some areas along the northern shorelines of Lake Ontario and Prince Edward County closer to 20 cm.

For regions such as Kitchener, Woodstock, Guelph, and Barrie, snowfall totals are projected to reach 10-15 cm. However, variability due to lake enhancement may result in some areas seeing lower amounts. The GTA is expected to receive closer to 5 cm, while the Niagara region could accumulate 5-10 cm, with localized heavier bands of snow influenced by Lake Erie.

In Deep Southwestern Ontario, snowfall amounts will decrease westward, with London forecasted to receive around 10 cm. Further southwest, including Sarnia, Windsor, and Chatham, totals are expected to remain under 5 cm.

It’s important to note that these totals do not account for the snow squalls expected to impact areas southeast of Lake Huron and Georgian Bay beginning Thursday morning. High-resolution models are still refining the locations of these squalls, but additional accumulations of 30-50 cm are possible in affected areas. Stay tuned for a detailed update in a separate forecast.

November 30, 2024

Snow Squalls Continue to Paralyze Ontario’s Snowbelt With Another 25-50cm of Snow by Monday

November 30, 2024/ Brennen Perry

It may have been a slow start to the winter season across Southern Ontario, but November is certainly ending with a bang. Above-average lake temperatures have fueled intense lake-effect snow squalls that have pummeled the snowbelt regions over the past few days.

As of Saturday evening, some of the hardest-hit areas, including Bracebridge, Gravenhurst, and Hanover, have reported snowfall totals ranging from 50 to 100 cm, with localized pockets even exceeding the 100 cm mark! This has led to massive issues on the roads as dozens of drivers were left stranded on Hwy 11 south of Gravenhurst due to extreme snowfall accumulation.

#ONStorm #ONwx We’re hearing reports of massive issues on Highway 11 Southbound between Gravenhurst and Washago due to the ongoing snow squalls.

Some vehicles are stuck in ditches and tow trucks are also getting stuck when trying to rescue them.

Plows are unable to clear the… pic.twitter.com/eYXyg1C6yi
— Instant Weather Ontario ❄️ (@IWeatherON) November 30, 2024

But the snowy barrage is far from over for these regions. By the time the squalls wind down late Monday, an additional 25 to 50 cm of snow could accumulate around areas east of Lake Huron and Georgian Bay.

Currently, intense snow squall activity is ongoing east of both lakes, with a focus on the Bala-to-Bracebridge corridor and the Tiverton-to-Walkerton stretch. These squalls are expected to remain mostly stationary overnight, with snowfall rates reaching 5 to 10 cm per hour. This could add another 25 to 50 cm of snow in already heavily affected areas by Sunday morning.

By Sunday morning, a shift in wind direction is anticipated, pushing the squalls further south. The Georgian Bay squall will likely bring a quick but intense blast of snow to Midland, Orillia, and Barrie. Meanwhile, the squall near Hanover is expected to dissipate by late morning, only to be replaced by a more robust squall moving in from the north, targeting Owen Sound and Kincardine.

This northern squall could stretch far enough inland to reach areas like Orangeville and perhaps even the Greater Toronto Area (GTA) by mid-afternoon. Although it won't last long enough to produce significant accumulation, it could lead to a sudden reduction in visibility and a quick 2 to 5 cm of snow. Similarly, Kitchener and Guelph may experience a few hours of heavy snow as the squall moves through.

By Sunday evening, the squalls are expected to settle southeast of Georgian Bay and Lake Huron. Collingwood and Meaford are likely to find themselves in the crosshairs of the Georgian Bay squall, while the Lake Huron squall will stretch from Goderich along the shoreline to Grand Bend and inland towards areas north of London.

According to the latest model data, the Georgian Bay squall may remain closer to the shoreline, potentially sparing Barrie and the Hwy 400 corridor from the heaviest snow.

However, London might not be as fortunate. The Lake Huron squall could extend into the city at times during the overnight hours and into early Monday. That said, the most intense snowfall rates are expected to stay north of London, impacting areas like Exeter, St. Marys, and Stratford.

Snow squall activity will persist throughout Monday and possibly into the overnight hours before tapering off late Tuesday morning. This will coincide with the arrival of a system from the west that could bring more widespread snowfall to parts of Southern Ontario. Details on that system will be shared in a separate forecast.

As is typical with snow squalls, snowfall totals will vary significantly depending on where the squalls settle. There is high confidence that regions in Muskoka and along much of the eastern Lake Huron shoreline will see an additional 25 to 50 cm of snow on top of what has already fallen.

Northwest of London, models indicate the Lake Huron squall could stall over the area from Sunday evening through Tuesday morning, potentially leading to localized totals exceeding 50 cm. Confidence in this scenario remains low, so we’ve held off from including it in our snowfall map for now.

The City of London is forecast to receive 15 to 25 cm of snow from the southern tip of the Lake Huron squall. However, there is potential for slightly higher totals depending on how far the squall extends inland.

The southern shoreline of Georgian Bay, including Collingwood and Meaford, is expected to see 25 to 50 cm of snow, with higher amounts likely in elevated areas such as Blue Mountain—great news for ski enthusiasts!

Simcoe County, including Barrie and Orillia, is forecast to receive lesser amounts, with 5 to 15 cm (possibly up to 20 cm) expected during the morning and afternoon hours on Sunday. Kitchener and Woodstock could also see 5 to 10 cm of snow from the Lake Huron squall.

Outside these core regions, snowfall will be minimal, with most areas receiving less than 5 cm. We are keeping an eye on the southern Niagara region and Prince Edward County, which could potentially be grazed by snow squall activity that is currently expected to remain south of the border. If it does drift north, localized totals of 5 to 10 cm could develop in areas like Fort Erie, Port Colborne, and Picton.

November 29, 2024

UPDATE: Squalls on Track to Bury Parts of Ontario’s Snowbelt in Up to 100cm of Snow by Saturday

November 29, 2024/ Brennen Perry

Confidence remains high for a very impactful snow squall event, which began east of Georgian Bay and Lake Huron Thursday evening. By the end of Saturday, some parts of the snowbelt region could be digging out of up to 50 to 100cm of snow!

Intense snow squall activity is expected to persist throughout Friday, with two primary squalls forming off Georgian Bay. The southern squall looks to settle between Honey Harbour and MacTier, extending inland toward the Highway 11 corridor from Washago to Bracebridge. This squall may reach as far inland as Haliburton and potentially Bancroft at times.

The second squall is projected to stretch across the northern tip of the Bruce Peninsula, coming onshore near Parry Sound. Unlike the southern squall, this one may not push as far inland, meaning Huntsville could see lighter impacts compared to areas like Bracebridge and Gravenhurst.

Snow squalls will also persist east of Lake Huron, with the most significant activity setting up just south of Hanover. Higher totals inland can be attributed to colder temperatures in elevated areas, where snow will accumulate more efficiently, compared to the slightly above-freezing conditions closer to the shoreline.

As Friday progresses, models suggest a brief wind shift by the evening, potentially driving the Georgian Bay squall south of Muskoka and into parts of northern Simcoe County.

There is some uncertainty about how far south this squall will drift, but most models suggest it will impact Midland, areas just north of Orillia, and into Rama. Within Orillia, accumulation could vary significantly, with lower totals in the south and much higher amounts in the north, reflecting the sharp gradient shown on our map.

By Saturday morning, the squall is expected to shift back north, realigning across the Parry Sound and Muskoka region. However, this time, it may consolidate into a singular band stretching from Parry Sound into northern Muskoka. This could spare Gravenhurst and Bracebridge from heavy snowfall on a second day, while Huntsville might see more snow as the squall locks into place for much of Saturday.

IMPORTANT

To provide the most accurate information, we are now breaking the snowfall totals into two separate forecasts. This forecast covers Friday and Saturday, while a second forecast will address Sunday and Monday and will be released on Saturday.

Our earlier forecast covered the entire four-day period and was intentionally broad to account for a wide range of possibilities. If the snowfall totals for your area are lower than what we initially predicted, it’s likely because your snow will fall later on Sunday or Monday.

As we’ve emphasized in previous updates, snow squalls are notoriously difficult to predict, with sharp gradients between areas of light snow and those with extreme accumulations.

In terms of snowfall totals, localized amounts are likely to exceed 50 cm and may even approach 100 cm by the end of Saturday in areas like Parry Sound, Bracebridge, and Gravenhurst. Similar totals are possible for Tobermory and Hanover.

Owen Sound and Collingwood could also experience heavy snow from a Lake Huron streamer, with higher elevations aiding accumulation. These areas could see snowfall ranging from 25 to 50 cm in the most affected zones.

Given the tight gradients, snowfall totals will decrease quickly as you move away from the primary snow squalls. Expect 15 to 30 cm across much of Grey-Bruce counties, northern Simcoe County, northern Kawartha Lakes, and Haliburton (excluding the heaviest-hit areas mentioned earlier).

For the rest of Southern Ontario, less than 5 cm is expected by the end of Saturday. However, regions like Barrie, Kitchener-Waterloo, and London could see some snowfall accumulation on Sunday and Monday as the winds shift late Saturday. So, if you’re hoping for snow in those areas, don’t give up yet!

Stay tuned for more updates, including our next detailed forecast on Saturday!

November 27, 2024

Intense Snow Squalls Could Bring Up to 50-100cm of Snow to Parts of Ontario This Weekend

November 27, 2024/ Brennen Perry

As we approach the first day of meteorological winter this Sunday, Ontario is preparing for a substantial blast of snow squalls that will make the season's arrival unmistakable. Beginning Thursday in Northern Ontario and Friday in Southern Ontario, persistent squalls are set to bury parts of the traditional snowbelt regions under as much as 50-100 cm of snow by the end of the weekend.

The first extended period of cold air has settled over Ontario, combining with the warm waters of the Great Lakes to create ideal conditions for lake effect snow. Parry Sound and Muskoka got a preview of what’s to come, waking up to a winter wonderland on Wednesday morning. While the lake effect snow machine has temporarily quieted as winds shift, it’s poised to roar back to life over the next several days.

Snow squall activity will restart as early as Thursday morning in Northern Ontario, with an intense band developing off Lake Superior. This narrow and powerful squall is expected to affect the corridor between Wawa and Sault Ste. Marie through Thursday and into Friday. Snowfall rates could reach up to 5 cm per hour, and if the band lingers over one area for an extended time, accumulation will add up quickly.

On Thursday, a system moving up the Northeastern U.S. will brush Southern Ontario. Most of the precipitation is expected to remain on the U.S. side of the border, but some areas in Ontario, including parts of the Greater Toronto Area (GTA) and Niagara region, could see light mixed precipitation or even their first flurries of the season. Little to no accumulation is expected, but slushy road conditions may develop for the Thursday morning commute.

As the system exits, winds will shift to a westerly or northwesterly direction late Thursday, triggering the return of lake-effect snow squalls. These squalls will intensify overnight and into Friday morning.

Current models suggest the primary snow squall band will stretch across the Bruce Peninsula, move over Georgian Bay, and come ashore between Parry Sound and MacTier. Further inland, areas along the Hwy 11 corridor, including Huntsville and Gravenhurst, will also be affected.

Additional squalls are expected off Lake Huron, impacting regions such as Kincardine, Owen Sound, Hanover, Wingham, and Mount Forest.

One of the biggest concerns is the potential for squalls to remain stationary over specific areas for extended periods. Models suggest some regions could face 24-48 hours of relentless snowfall, with rates reaching 3-5 cm per hour from Friday morning to early Sunday.

Road conditions are expected to deteriorate rapidly, and travel in affected areas should be avoided starting late Thursday. Near-zero visibility, combined with rapid snow accumulation and blowing snow, may create blizzard-like conditions. Improvements are unlikely until late in the weekend or even early next week.

By Sunday morning, a slight change in wind direction could push the Georgian Bay snow squalls southward into Simcoe County and the Kawartha Lakes region. Similarly, Lake Huron squalls may shift to target areas like Goderich, Stratford, and Listowel.

Lake Erie and Lake Ontario could also generate brief lake effect activity on Sunday, potentially impacting the Southern Niagara region, Prince Edward County, and Kingston.

📣 Significant Weather Outlooks for Thursday to Sunday.

❄️ Multiple rounds of lake effect snow.
🗺️ East and southeast of Lake Superior, Georgian Bay, Lake Huron.

Be sure to plan ahead if you are in the effected areas!#ONstorm #ONwx pic.twitter.com/PSHBYnm6Ud
— ECCC Weather Ontario (@ECCCWeatherON) November 27, 2024

Environment Canada is also mentioning the potential for multiple rounds of lake-effect snow and squalls. They have highlighted areas east of Lake Huron and Georgian Bay in a ‘high’ weather threat for Friday and Saturday with locally up to 20-30cm of snow on both days.

There is also a ‘moderate’ weather threat on Sunday southeast of Lake Huron and Georgian Bay with locally up to 10-20cm. Combined, Environment Canada’s forecast is suggesting that snowfall totals could range from 50 to 80cm over those 3 days!

Snow squalls are highly localized, often only a few dozen kilometres wide, meaning snowfall totals can vary dramatically over short distances. One area might receive 50+ cm, while another just down the road may see barely a dusting.

Because of this variability, we are focusing on general zones for now. Higher-resolution models will help refine the forecast as we approach the weekend, and updates will be provided accordingly.

Snowfall totals across the traditional snowbelt regions could be significant:

50-100 cm: Areas east of Georgian Bay and Lake Huron, including Bracebridge, Gravenhurst, Huntsville, Parry Sound, Owen Sound, Kincardine, Goderich, and Hanover.
25-50 cm: Surrounding regions, including the Bruce Peninsula, Collingwood, Midland, and Orillia. Totals will drop quickly further from the snowbelt.
5-15 cm: Localized areas in the Southern Niagara region (e.g., Port Colborne and Fort Erie) and Kingston, mainly on Sunday, if lake effect activity drifts north of the border.

For Northern Ontario, the corridor between Wawa and Sault Ste. Marie is expected to see snowfall totals between 50-100 cm from Thursday morning through late Sunday. Accumulations will taper off sharply as you move away from the Lake Superior shoreline.

Stay tuned for further updates in the coming days as we break down this dynamic weather event and provide more detailed forecast maps.

November 25, 2024

Winter Roars Into Ontario This Week With Freezing Rain Threat; Snow Squalls Could Dump Up to 50cm of Snow

November 25, 2024/ Brennen Perry

While winter has gotten off to a slow start across Southern Ontario, with many areas only seeing their first snowfall within the past week or two, it seems that change is on the way. November is shaping up to go out like a lion, as Mother Nature makes up for lost time.

A significant pattern shift is expected to bring the threat of freezing rain late Monday across Central and Eastern Ontario. This will be followed by multiple weaker systems across the Great Lakes region and colder air flooding into the province.

That colder air will set the stage for what could become our first major snow squall event later this week and into the weekend. In some typical snowbelt areas, snowfall could be measured in feet (30+ cm) by this time next week!

Let’s break down what is shaping up to be a very dynamic and active forecast over the next five to seven days, starting with the freezing rain threat.

Freezing Rain Risk: Monday into Tuesday

A system is expected to move into Southwestern Ontario and the Golden Horseshoe beginning Monday afternoon. With temperatures forecasted to stay well above freezing in these areas, precipitation will fall as rain.

However, as the system moves northeast into Central and Eastern Ontario after midnight, it will encounter a stubborn layer of colder air near the surface. Temperatures hovering near or just below freezing may allow some of the rain to fall as freezing rain overnight into early Tuesday morning.

There remains some uncertainty about how widespread this pocket of cold air will be. Higher-elevation areas of Central and Eastern Ontario, including Bancroft, Barry’s Bay, and Algonquin Park, are most likely to experience freezing rain. It’s also possible for freezing rain to extend westward to Muskoka and Parry Sound, and eastward into the Ottawa Valley, including the City of Ottawa.

For Bancroft, Barry’s Bay, and Algonquin Park, ice accretion totals could reach 2-4 mm by Tuesday morning, though any ice will quickly melt after sunrise as temperatures rise above freezing by late morning. In Muskoka and the Ottawa Valley, a thin layer of ice on untreated surfaces is possible, which could make for a slow Tuesday morning commute. There is a slight chance of school bus cancellations in affected areas.

Northern Ontario: Heavy Snowfall Ahead

Northern Ontario will experience heavy snow from this same system, as colder air dominates in the region. Light to moderate snowfall is expected to begin in Northwestern Ontario by early Monday afternoon, gradually spreading eastward into the evening and overnight.

Snow will continue across Northern Ontario throughout Tuesday, with the heaviest snowfall expected near the Quebec border in Northeastern Ontario. Snowfall will gradually ease later on Tuesday and into early Wednesday but could persist near James Bay in a zone extending from Hearst to Lansdowne House.

Over three days, snowfall totals will generally range from 10 to 20 cm across Northern Ontario. Far Northern Ontario near James Bay could see totals exceeding 20 cm by Thursday, while lake-enhanced snowfall southeast of Lake Superior, including Sault Ste. Marie, could push totals closer to 30 cm.

Thunder Bay is expected to see slightly less snow, as the city may end up in a drier part of the system. Forecasts currently suggest snowfall amounts of 5 to 10 cm in this area.

Southern Ontario: Cold Air and Lake Effect Snow

As the system moves out of Southern Ontario late Tuesday, a surge of cold air will follow in its wake. This will briefly activate the lake effect snow machine around Lake Huron and Georgian Bay beginning Tuesday evening and lasting into Wednesday.

At this time, temperatures are expected to hover near the freezing mark, which could limit significant accumulation. The most likely target zone for this initial burst of lake effect snow includes areas east of Georgian Bay, such as Parry Sound, Huntsville, and Bracebridge. These areas could see 10-15 cm, with localized amounts of up to 20 cm by the time snow bands taper off Wednesday evening.

For higher elevations southeast of Owen Sound, including Hanover, Markdale, Shelburne, and Orangeville, up to 5-10 cm of snow is possible, as cooler temperatures in these areas will allow snow to accumulate more easily. Surrounding regions, including parts of the Greater Toronto Area, may see just a few light flurries.

End of the Week: A Snow Squall Event Looms

Lake effect snow will temporarily pause as another system slides through the Great Lakes region. However, this system appears to stay largely south of the border, bringing only a few flurries or light showers to areas near Lake Erie and the Golden Horseshoe early Thursday.

As we approach the weekend, Southern Ontario will see its coldest air of the season so far, with overnight lows plunging to several degrees below freezing across much of the province.

A dominant westerly to northwesterly wind is expected to develop Friday and persist into the weekend. This setup will create ideal conditions for intense snow squalls off Lake Huron, Lake Superior, and Georgian Bay starting Friday afternoon and lasting through the weekend.

These snow squalls could bring significant snowfall totals, blowing snow, and near-zero visibility to localized areas in the snowbelt. Travel could become difficult or even dangerous in the hardest-hit regions.

Based on the current forecasted wind direction, regions including Kincardine, Owen Sound, Hanover, Midland, Oro, Orillia, and Gravenhurst are likely to see the heaviest impacts. This also extends up into Northern Ontario around the Lake Superior shoreline with Sault Ste. Marie in the bullseye. Some locations within this zone could receive up to 50 cm of snow by the end of the weekend.

Snow Squall Uncertainty

It’s important to note that snow squalls are highly localized events, and not everyone will experience intense snowfall totals. One area may receive significant snow accumulations, while locations just a few kilometres away might see only a dusting.

Confidence is high that some sort of snow squall event will occur, but exact locations will depend on the finer details of wind direction and temperatures.

Environment Canada has also mentioned the potential for significant snow squalls later this week:

The first significant lake effect snow of the season is likely beginning Friday. This has the potential to be a highly disruptive and prolonged event for areas near Lake Huron, Georgian Bay and eastern Lake Superior. While confidence is medium to high that lake effect snow and blowing snow will occur, confidence in exact locations to be affected as well as snowfall accumulations is low. As is normally the case in these situations, snowfall amounts will be highly variable. Some areas may see well in excess of 50 cm by the end of the weekend. - Environment Canada

Stay tuned for updated forecasts in the coming days as higher-resolution models provide more details. We’ll refine the snow squall forecast and pinpoint areas most at risk.

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