Winter Storm Threat Looms for Ontario With Up to 30cm of Snow and 60mm of Rain by Thursday

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The beginning of April in Ontario is setting the stage for a dramatic shift in weather, as a moisture-laden system promises a variety of conditions across the region. This shift includes the potential for flooding rains, with predictions of 40 to 60mm of rain in parts of the Golden Horseshoe.

In addition, areas of Central, Eastern, and Northern Ontario are on track for significant snowfall, with totals ranging from 20 to 35cm in the most affected areas!

As outlined in our previous forecasts, this bout of active weather kicked off with strong wind gusts on Tuesday afternoon, expected to persist into the night.

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With the wind gradually subsiding, our attention now shifts to the substantial moisture being pumped into our region from the Gulf of Mexico. Initially, this precipitation will begin as heavy rain, with intense downpours expected overnight and into Wednesday morning across the Greater Toronto Area, extending into Central and Eastern Ontario.

However, by late Wednesday, colder air from the northwest will sweep in, prompting a gradual transition from rain to wet snow by the late afternoon in parts of Central and Eastern Ontario. Northeastern Ontario, already under colder air by the morning, may experience snow for the duration of this event.

The challenge in forecasting this system lies in the temperatures hovering near the freezing point, significantly impacting snow accumulation. Additionally, model predictions vary on the timing of the transition from rain to snow, some suggesting it won't occur until late Wednesday evening, while others indicate it will occur around 2 to 5 PM.

By Wednesday night, most regions, including the Golden Horseshoe, are expected to have transitioned to wet snow, with light to moderate snowfall persisting into Thursday morning and afternoon, concluding by Thursday evening.

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Elevation will be a crucial determinant of snowfall totals, with the highest accumulations forecasted southwest of Ottawa in Eastern Ontario's elevated areas. This includes Bancroft, Barry’s Bay, Algonquin Park, and Renfrew, with expected snowfall totals ranging from 20 to 35cm by Thursday's end.

For the Ottawa Valley, including Ottawa, Cornwall, Brockville, and Pembroke, snowfall totals are more uncertain, ranging from 10 to 25cm. This variability will depend on local dynamics and the ability of snow to stick to the ground. There is the potential that some areas will exceed our forecast if the snow can stick more efficiently to the ground.

Further south and westward, snowfall totals are expected to range from 5 to 15cm, including Kingston, Peterborough, Huntsville, and Sundridge. Local areas north of the Greater Toronto Area, particularly along the higher elevations of the Oak Ridges Moraine and Dundalk Highlands, may also see up to 10 to 15cm. This forecast is heavily dependent on temperatures, which may not drop below freezing until Thursday morning, affecting accumulation.

Areas east of Georgian Bay and away from Lake Ontario's shoreline are likely to exceed 5cm but should remain under 10cm. Regions directly along the Lake Ontario shoreline and parts of Southwestern Ontario will experience less than 5cm of snow, as rain will dominate these areas.

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In addition to significant snowfall in Central and Eastern Ontario, significant rainfall is anticipated along Lake Ontario's shoreline, including Prince Edward County, Oshawa, Toronto, Mississauga, Burlington, Hamilton, and Grimsby, with potential totals ranging from 40 to 60mm. This rapid accumulation, especially in urban areas prone to flash flooding, poses a substantial flooding risk.

Rainfall totals for the rest of the Golden Horseshoe, extending to the Dundalk Highlands and the Bruce Peninsula, are projected to range from between 30 to 50mm. Further north and east, where more snow is expected to mix in, rainfall totals of 20 to 40mm are likely.

Southwestern Ontario is expected to see lower rainfall totals of 10 to 30mm, with Deep Southwestern Ontario receiving less than 15mm.

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In Northern Ontario, heavy snow is the main concern, with the highest totals just north of Sudbury, anticipating 20 to 35cm of snow from Wednesday morning through Thursday afternoon.

For Sudbury and North Bay, snowfall predictions range from 10 to 25cm. Lower amounts are expected towards Georgian Bay due to rain mixing in, while totals will decrease sharply further north and west due to limited moisture.

Messy System Targets Ontario This Weekend With Significant Rain to the South and Heavy Snow to the North

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The opening week of March has been notably calm in Southern Ontario, with minimal active weather events and a generous serving of above-seasonal warmth and predominantly clear skies. A few rain spells have visited us over the last several days, with temperatures occasionally leaping into the 20s, setting records on Tuesday and Wednesday in some locations.

Yet, as we move towards the weekend, we anticipate a shift, with a looming system poised to bring substantial rainfall across Southern Ontario. In contrast, those in Northeastern Ontario should ready themselves for a considerable snowfall, with some areas potentially seeing up to 30cm.

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Following the departure of this system by late Saturday, a period of sub-freezing temperatures will return to Southern Ontario on Sunday, extending into Monday. This shift sets the stage for the possibility of snow accumulation in parts of Central Ontario, particularly Eastern Ontario and near Lake Huron and Georgian Bay, at the onset of next week.

Southwestern Ontario has already begun to experience heavy rain on Friday evening, anticipated to last into Saturday. The heaviest downpours are expected overnight and into the morning hours. The rain will start around midnight for Eastern and Central Ontario and is likely to persist into early Saturday afternoon.

Accompanying the rain on Saturday will be a surge of mild air, with daytime highs expected to reach the upper single digits, and potentially the low teens throughout Southern Ontario. While the Northern parts of the province will see a more resilient cold air mass, resulting in snow rather than rain.

Northeastern Ontario will see the onset of snow around midnight, with the mixing line expected near Elliot Lake to slightly north of Sudbury. Areas north of the line, including Chapleau and Timmins, will experience significant snowfall overnight into Saturday morning, with intense snow at times throughout the day.

Both the rain in the south and snow in the north will diminish as the evening progresses, as the system departs our region. By Saturday evening, a switch from rain to snow is possible in the northern regions of Central and Eastern Ontario. However, with the ground still saturated from previous rains and temperatures hovering just above freezing, significant accumulation is not anticipated.

Overnight into Sunday, light to moderate snowfall may occur in regions traditionally affected by lake-effect snow around Lake Huron and Georgian Bay. Eastern Ontario might also receive some flurries from the lingering bands of system-related precipitation. Currently, we predict a few centimetres of snow at most, though certain areas along the Lake Huron shore and south of Georgian Bay could receive up to 5-10cm. A more detailed forecast for Sunday's snow will be released on Saturday.

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Regarding total rainfall, Central and Eastern Ontario are set to receive the highest totals, with 25 to 40mm expected by Saturday's end, which may cause localized flooding. Widespread totals of 15 to 30mm are projected across most of Southern Ontario. Areas near the Golden Horseshoe, along the southern Georgian Bay shoreline, and over Algonquin Park could see a dry pocket leading to slightly less rain, with 10 to 20mm anticipated.

As for Northeastern Ontario, snow will be the dominant story with snowfall totals of 20 to 30cm in a broad swath encompassing Timmins, Kirkland Lake, Cochrane, and Kapuskasing. A sharp drop-off in accumulation is forecasted closer to the rain-snow mix to the south and drier areas to the north.

The Chapleau area can expect 10 to 20cm of snow, while less than 10cm is predicted for North Bay, Sudbury, Elliot Lake, and Sault Ste. Marie, with rain as the primary form of precipitation for those regions.

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Weather Whiplash in Ontario With Record-Breaking Heat, Severe Thunderstorm Risk & Flash Freeze This Week

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Get ready for a wild weather ride, Ontario! The old saying will hold true this week: "If you don't like the weather in Ontario, just wait five minutes—it'll change!" And change it will, with a full spectrum of seasons unfurling over the next 48 hours.

As we previously hinted, a ‘heatwave’ is set to roll in for Tuesday and Wednesday, with temperatures climbing into the teens. Parts of Deep Southwestern Ontario are even teasing the 20°C mark, according to some models!

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Thunderstorms are on the agenda for Tuesday, starting with morning storms and a potential severe risk by the afternoon and evening.

Fog, a recurring theme this season, is slated to make a comeback in certain areas on Tuesday and Wednesday. This will be accompanied by heavy rain, dumping 15-30mm by Wednesday morning. For parts of Northern Ontario, we could be looking at significant snowfall totals as the cold air hangs on there. This includes Kenora, Dryden, Kapuskasing, Cochrane and Timmins.

Take a look at Windsor's 10-day forecast—it's a real temperature roller coaster. We're climbing to the first high on Wednesday with temperatures soaring over 15°C, then taking a dive back to near seasonal norms by Thursday.

But hold on tight! We're heading back up for another warm spell this weekend, with the mercury potentially flirting with the 20°C mark by Monday.

For some perspective, the average high for Windsor at this time of year hovers around 3°C. However, the upcoming forecast anticipates highs that will consistently top the seasonal average. And this pattern of temperature swings? It's set to stick around into the early days of March.

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But don't pack away your winter gear just yet!

Remember, it's still February, despite what the balmy temperatures might suggest. Winter is gearing up for a comeback by Wednesday morning and afternoon. A sharp cold front will sweep through the province, one of the steepest we've seen in quite some time, with temperatures plummeting from the teens to below freezing in just a few hours.

Given the expected rain and mixed precipitation during this cooldown, we're likely to see road conditions turn treacherous with ice on Wednesday. A tricky commute is on the cards for Wednesday afternoon, and we can't dismiss the potential for school bus cancellations if the flash freeze risk materializes as the models predict.

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From late Wednesday into Thursday, snow squalls are expected to revisit the usual snowbelt regions, with wind chills plunging to near -20°C—a stark contrast to Tuesday's near-record warmth.

And the temperature roller coaster doesn't stop there. As we look towards the weekend and into early next week, another significant warm-up is on the horizon. Because these rapid temperature fluctuations are definitely healthy for our ecosystem! 🫠

We're putting together a detailed forecast, complete with several maps to navigate this complex weather pattern. It's a bit of a task, so bear with us as we compile all the necessary information. Stay tuned!

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Winter Returns to Southern Ontario This Week With Heavy Rainfall Followed by Up to 15-20cm of Lake-Effect Snow by Tuesday

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It's hard to believe, but we're nearly a week away from Christmas Day, and most of Southern Ontario, except the snowbelt region, has yet to witness a significant snowfall this season. The little snow we've had quickly vanished, courtesy of the unusually mild start to December, with temperatures reminiscent of late fall or early spring.

However, a shift in the weather pattern is on the horizon as we approach the final week before Christmas, bringing the return of more conventional winter conditions. This change includes widespread snowfall expected between Monday and Tuesday, intensified by heavier lake effect snow bands around Lake Huron, Georgian Bay, and even Lake Ontario.

Temperatures are also poised to plummet, with much colder air sweeping across the province. We anticipate a brisk Tuesday morning, where, factoring in wind chill, it could feel like the negative teens or even lower, a stark contrast to the double-digit temperatures we've enjoyed on several days in recent weeks.

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Before Southern Ontario resumes its typical winter programming, a spell of milder weather is still holding on this weekend. As of Sunday afternoon, widespread rainfall is sweeping across the region.

Another bout of intense precipitation is set to hit Eastern Ontario overnight into Monday morning, courtesy of the outer precipitation bands of a potent system moving up the US East Coast. While the brunt of this storm will stay to our east, the trajectory does bring substantial rain to Extreme Eastern Ontario along the international border.

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Rainfall totals across Southern Ontario for Sunday are projected to be between 10 to 15mm, with some areas receiving up to 20 to 25mm. Eastern Ontario is expected to experience heavier rainfall, with accumulations of 30 to 50mm around Kingston, Ottawa, Brockville, and Cornwall. Locally, totals exceeding 50mm can’t be ruled out, particularly east of Ottawa.

The rain should recede across Southern Ontario by late Sunday evening, although Eastern Ontario may continue to experience heavy rain into Monday morning.

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Following the system to our east, a gradual cooling will ensue on Monday, with temperatures nearing the freezing mark later in the day, starting in Southwestern and Central Ontario.

Late Monday, a wave of weak precipitation is expected to track across Southern Ontario, beginning with light drizzle and transitioning to flurries as temperatures fall. There's some uncertainty regarding the intensity of this snowfall, as lake enhancement off the Great Lakes will primarily drive it.

Additionally, localized snow squalls are anticipated to develop off Lake Huron, Georgian Bay, and Lake Ontario, starting Monday evening and persisting into early Tuesday.

Steady snowfall is forecasted across Southern Ontario during the overnight hours and early Tuesday morning. While the heaviest snow will be concentrated near the lakes, it seems that even inland areas in Eastern and Central Ontario will see a light dusting.

Our focus is on areas south of Georgian Bay, Lake Huron, and parts of the Niagara region, where heavier snow bands are expected off the lakes.

The snow should taper off by Tuesday morning's end, though some lake-effect flurries might linger in the snowbelt regions.

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Current projections indicate the potential for 10 to 20cm of snow in two specific areas: south of Collingwood over the Blue Mountains off Georgian Bay and east of Sarnia around Petrolia and Lambton Shores, due to expected heavier lake effect snow overnight into Tuesday morning. Not everyone will experience such significant snowfall, as the bands will be narrow and unpredictable.

Heavier snow is also forecasted along the southern shoreline of Lake Ontario in the Niagara region, with 10 to 15cm possible between Grimsby and Niagara-on-the-Lake, while the rest of the Niagara region might see around 5cm.

Away from the lakes, the models are divided, with some higher-resolution models predicting less snow for Central and Eastern Ontario, while others suggest much more. We're currently estimating a general 5 to 10cm of snow, though actual totals will likely vary across the region.

Hence, some areas might exceed these predictions, especially in Eastern Ontario, while others may not reach the 5cm mark. The rest of Southern Ontario, including the GTA and Deep Southwestern Ontario, should expect a few centimetres of snow over the coming days.

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