NORTHERN ONTARIO: Thunderstorm Forecast for Thursday, August 17, 2023
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Read more in our full forecast here.
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ONTARIO: Thunderstorm Forecast for Thursday, August 17, 2023
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FORECAST UPDATE - Thursday Morning
Based on the latest data, it appears that the forecasted line of storms later today will be a lot weaker than expected. The environment just isn’t materializing as earlier data indicated which will mean the line currently over Michigan will likely fall apart as it crosses Lake Huron.
We will continue to hold with an ‘isolated’ risk across all of Southern Ontario as we can’t rule out a few marginally severe storms ahead of this line. It’s just very questionable how strong these storms will actually get at this point. Main storm hazards include 90 km/h wind gusts, hail up to the size of quarters and localized heavy rainfall. However, the ‘slight’ risk we had in our initial forecast has been replaced by the ‘isolated’ risk.
INITIAL FORECAST
As we venture into another Thursday in Southern Ontario, the familiar tune of severe thunderstorms is once again on the horizon. This time around, the risk is more extensive, featuring a line of potent thunderstorms that is set to cross Southern Ontario, starting Thursday afternoon and persisting throughout the day.
Though the overall severe threat is expected to max out at a 'slight' risk, it's important to note that the impact could be broader compared to prior occurrences. The main threats will include 100 km/h wind gusts, hail up to the size of ping pong balls and localized flash flooding.
This isn't an event with isolated, localized storms confined to specific areas. Instead, a linear arrangement of storms will extend from North Bay to Windsor, essentially encompassing a significant portion of Southern Ontario. While not everyone will encounter severe conditions, the line's potency will vary, so the degree of severity won't be uniform.
The timing of this event still bears a level of uncertainty. Initial model data hinted at the line's potential arrival during the late morning and early afternoon hours, intensifying throughout the day as the dynamic atmospheric conditions provide ample fuel to the line of storms. This line will start in the west across Northeastern Ontario and into Southwestern Ontario.
However, the most recent data nudges the line's onset closer to mid-afternoon. This shift has implications for the severity of the threat. With more daylight hours for atmospheric build-up, the storms could be more robust.
Additionally, we might see isolated storms forming ahead of the main line, particularly in Central and Eastern Ontario during the afternoon. These isolated storms could encompass all the classic severe threats: significant hail, potent wind gusts, and even tornadoes.
As the line of storms progresses, it could evolve into a 'squall line,' historically known for delivering widespread damaging winds and sporadic tornadoes across our region.
The hail risk seems relatively lower compared to recent events where we’ve seen hail as large as baseballs. However, isolated storms preceding the line may still pack the punch of large hail, possibly reaching the size of ping-pong balls. Inside the line itself, the hail sizes are anticipated to max out around quarter-sized.
The storm threat will carry it eastward, reaching the Golden Horseshoe during dinner hours and subsequently moving into Eastern Ontario by late evening. It's important to remember that this timeframe is tentative and may shift a few hours earlier or later.
Adding to the concern of damaging winds, flash flooding is becoming a significant issue we've identified in the model data. Certain areas might experience multiple waves of precipitation, particularly in the Ottawa Valley where persistent storm activity ahead of the main line could transpire. In such scenarios, local rainfall totals could exceed 100mm by the end of the day.
ONTARIO: Thunderstorm Forecast for Wednesday, August 16, 2023
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Thunderstorms are currently not expected across Southern Ontario on Wednesday.
NORTHERN ONTARIO: Thunderstorm Forecast for Wednesday, August 16, 2023
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The risk of severe weather is set to make a return to Northern Ontario on Wednesday, marked by the anticipated formation of a potent line of storms during the late afternoon. A robust environment is expected to develop ahead of the line of storms, providing substantial energy as it traverses Northwestern Ontario. This environment could lead to various severe hazards, including the likelihood of a couple of tornadoes, hail of golf ball size, and gusts of wind surpassing 110 km/h.
As of the latest data, the onset of storm initiation is projected somewhere in the region between the Manitoba border and the Dryden area. The initiation is estimated to unfold during the time frame of 2 - 5 PM. During this period, the tornado and hail risk is expected to be at its maximum. These isolated discrete cells have the potential to grow into rotating supercells, heightening the risk of tornadoes and large hail.
As the late afternoon approaches, these isolated storms are forecasted to merge together, culminating in the formation of a squall line extending from Atikokan to Armstrong. The main storm concern will shift towards widespread damaging wind gusts, surpassing speeds of 90 km/h. While the possibility of large hail and tornadoes remains, their overall likelihood is anticipated to wane as the merge occurs.
The line is anticipated to reach the Thunder Bay area by early evening. At this point, the precise severity of the storm threat becomes less certain, so we have placed them in between the slight and strong risk on our map. However, Thunder Bay is likely to see strong storms either way.
ONTARIO: Thunderstorm Forecast for Tuesday, August 15, 2023
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Heavy rainfall with embedded non-severe thunderstorms is expected to affect Southwestern Ontario into the Golden Horseshoe during the morning and afternoon on Tuesday. These storms could bring strong wind gusts up to 80 km/h wind gusts, dime-sized hail and localized flash flooding. Thunderstorm activity may also linger into Tuesday evening and overnight.
NORTHERN ONTARIO: Thunderstorm Forecast for Tuesday, August 15, 2023
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Thunderstorms are currently not expected across Northern Ontario on Tuesday.
ONTARIO: Thunderstorm Forecast for Monday, August 14, 2023
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Thunderstorms are currently not expected across Southern Ontario on Monday.
NORTHERN ONTARIO: Thunderstorm Forecast for Monday, August 14, 2023
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Thunderstorms are currently not expected across Northern Ontario on Monday.
ONTARIO: Thunderstorm Forecast for Sunday, August 13, 2023
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Thunderstorms are currently not expected across Southern Ontario on Sunday.
NORTHERN ONTARIO: Thunderstorm Forecast for Sunday, August 13, 2023
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Thunderstorms are currently not expected across Northern Ontario on Sunday.
ONTARIO: Thunderstorm Forecast for Saturday, August 12, 2023
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As we gear up for the weekend across Southern Ontario, we're keeping a close watch on a rather strong severe weather threat. Unlike recent occurrences which centred around Deep Southwestern Ontario or the Ottawa Valley, this time the spotlight is shifting to the GTA, Niagara, and Kingston regions.
We expect to see an intense atmospheric setup extending from the Lake Erie shoreline up into Central Ontario around Lake Simcoe. This dynamic environment is expected to extend eastward, covering the Golden Horseshoe and areas along the Lake Ontario shoreline.
Given the environment, it's likely that any storms forming within this zone could quickly turn severe. The main concern here is the potential for destructive wind gusts, possibly reaching up to 110 km/h. There's also a chance we could see some sizable hail, even up to the size of ping-pong balls.
Now, let's talk tornadoes. The risk is certainly present, particularly around Lake Ontario, which includes the GTA, Niagara, and Kingston regions. While the possibility of an isolated tornado can't be ruled out in most of Southern Ontario, it's more uncertain outside the 'one or two tornadoes' zone.
Now, about timing. Pinpointing the exact starting point of these storms is a bit tricky right now. The latest models suggest scattered storm development across Southern Ontario beginning early Saturday afternoon. We might even see some stronger storms early in the morning, though severe potential might be lower at that time.
For areas in the west, like London, Kitchener, and Barrie, the primary storm risk will likely be during the early afternoon, contingent on where these storms kick-off. The GTA and Niagara region might experience the storm threat lingering into the mid to late afternoon, possibly arriving in multiple rounds. Expect the storm activity to shift eastward as the day progresses, with Kingston in the spotlight around 3 - 6 PM. The severity will ease by evening, dissipating shortly after dinner.
It's worth noting that while we have every part of Southern Ontario at some level of severe risk, most areas may not experience storms at all on Saturday. These storms will be highly localized, impacting only a small area. But within this confined zone, they could pack quite a punch. In Deep Southwestern Ontario and the Ottawa Valley, the potential for severe weather is somewhat lower, falling into the isolated to slight severe threat category.
As always, we're staying on top of the latest data, ready to adjust this forecast as needed. Stay tuned for updates, either later tonight or early tomorrow, to stay informed on the very latest. Your safety matters and is our priority!
NORTHERN ONTARIO: Thunderstorm Forecast for Saturday, August 12, 2023
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Thunderstorms are currently not expected across Northern Ontario on Saturday.
ONTARIO: Thunderstorm Forecast for Friday, August 11, 2023
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There's the potential for some stormy weather in Deep Southwestern Ontario during the evening on Friday. While the risk isn't entirely clear-cut, we want you to be aware of what's on the horizon.
Isolated storms are expected to pop up over Michigan and could make their way into the Windsor and Chatham region after dinner time. For these areas, we're putting them under a 'slight' severe risk. The main concerns here are strong wind gusts, possibly reaching speeds of up to 100 km/h, and hail about the size of quarters. We also can't completely rule out the chance of a tornado, though it's not a high likelihood.
Now, here's where things get a bit tricky. The uncertainty comes from the timing of these storms. Some models are suggesting that storm development might happen quite late, even after 9 to 11 PM, long after the sun has gone down. The question is, can these storms still gather enough energy from the atmosphere to turn severe even in the late hours? The environment does seem to suggest that it's possible, which means the severe risk might linger past midnight and into the early hours of Saturday.
NORTHERN ONTARIO: Thunderstorm Forecast for Friday, August 11, 2023
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Thunderstorms are currently not expected across Northern Ontario on Friday.
ONTARIO: Thunderstorm Forecast for Thursday, August 10, 2023
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As we look ahead to Thursday, there's a growing risk of severe thunderstorms, and we have made some important changes to our forecast. Here's what you need to know:
We've updated our thunderstorm risk forecast to include a 'strong' chance of severe storms, covering a large area from Lake Huron through Lake Simcoe and extending into parts of the Ottawa Valley. Also, Central and Eastern Ontario, including the Greater Toronto Area (GTA), are now under a 'slight' risk. This means we're seeing the potential for stronger storms than previously thought, especially in those areas.
The timing of storm development has shifted a bit. We expect isolated storms to kick off sometime between 11 am and 2 pm. These storms are likely to pop up around Owen Sound and Georgian Bay before moving inland during the early afternoon.
The environment is favourable for some of these storms to become supercells around Lake Simcoe and south of Georgian Bay. These storms have the potential to bring threats including hail up to the size of golf balls and damaging wind gusts reaching up to 110 km/h. We could also see one or two tornadoes if these storms manage to get rotating which the environment could support.
As the day goes on, the focus of the storm threat will shift eastward. Isolated storms will come together to form a line of storms. We may even see a few isolated supercells ahead of the main line throughout the Ottawa Valley which would present a buffet of storm threats including large hail, destructive wind gusts and tornadoes. Throughout this line of storms, the main worry is strong winds that could cause damage. But, we can't ignore the possibility of large hail and a few isolated tornadoes either.
We're also keeping an eye on Southwestern Ontario, where we could see isolated storms forming off Lake Huron. This might affect places like Goderich and Kitchener-Waterloo, but it's a bit uncertain at the moment.
By the late afternoon, the severe weather risk should start to decrease from west to east.
NORTHERN ONTARIO: Thunderstorm Forecast for Thursday, August 10, 2023
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Thunderstorms are currently not expected across Northern Ontario on Thursday.
ONTARIO: Thunderstorm Forecast for Thursday, August 10, 2023
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Prepare for a resurgence of thunderstorm activity across Southern Ontario on Thursday. This will be accompanied by an isolated severe threat spanning from Southwestern Ontario through the Golden Horseshoe and extending into Eastern Ontario. Our attention is focused on two distinct areas of storm development in Southern Ontario.
Firstly, storms are anticipated to originate over Lake Huron, tracking into the Greater Toronto Area (GTA) and Niagara region. Simultaneously, another zone of storm development is anticipated, ranging from Lake Simcoe up to Renfrew. These storms are projected to commence during the early afternoon hours and advance eastward throughout the day.
While these storms are not expected to be widespread, they possess the potential to reach marginally severe levels, accompanied by wind gusts of up to 90 km/h, hail reaching the size of quarters, and substantial rainfall. Additionally, there exists a chance of isolated tornado activity.
The precise timing of these storm formations introduces an element of uncertainty that could influence the overall storm threat. Delayed storm initiation would elevate the severity threat, as increased daylight heating would contribute to heightened energy levels. Conversely, some models indicate the potential for initiation further east, possibly even outside of Ontario.
Currently, we are sticking with an isolated severe threat. It is crucial to note that not all regions within the severe risk area will experience storm activity on Thursday. Any storm occurrence will be localized, impacting a limited area.
In our upcoming Wednesday evening update, we might consider introducing a more localized 'slight' severe risk zone if the environmental conditions indicate a stronger potential than initially anticipated.
ONTARIO: Thunderstorm Forecast for Wednesday, August 9, 2023
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Thunderstorms are currently not expected across Southern Ontario on Wednesday.
NORTHERN ONTARIO: Thunderstorm Forecast for Wednesday, August 9, 2023
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Expect scattered thunderstorms to impact much of Northeastern Ontario during the afternoon and early evening on Wednesday. The atmospheric conditions are conducive for a few of these storms to escalate to severe levels, with a particular focus on the area around Elliot Lake and Sault Ste. Marie.
Current indications point towards the possibility of one or two discrete supercells forming within this region between 1-4 PM. These storms could carry slight severe threats, including hail up to the size of ping pong balls, wind gusts reaching speeds of 100 km/h, and a potential for an isolated tornado.
Moving further across Northeastern Ontario, extending along the Quebec border, there is an isolated risk of severe weather. While some storms might only reach marginally severe levels, it's important to note that we can't entirely dismiss the possibility of stronger storms, including the potential for tornadoes, anywhere in Northeastern Ontario.
NORTHERN ONTARIO: Thunderstorm Forecast for Wednesday, August 9, 2023
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Thunderstorm activity is expected to develop in Northeastern Ontario during the day on Wednesday. It appears that the environment will be favourable for some of these storms to approach marginally severe levels, especially along the Quebec border. All severe threats including an isolated tornado risk are on the table. We will have a more detailed forecast on Tuesday evening.
