ONTARIO: Thunderstorm Forecast for Friday, September 1, 2023
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Thunderstorms are currently not expected across Southern Ontario on Friday.
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ONTARIO: Thunderstorm Forecast for Wednesday, August 30, 2023
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Thunderstorms are currently not expected across Southern Ontario on Wednesday.
ONTARIO: Thunderstorm Forecast for Tuesday, August 29, 2023
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Thunderstorms are currently not expected across Southern Ontario on Tuesday.
ONTARIO: Thunderstorm Forecast for Monday, August 28, 2023
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Thunderstorms are currently not expected across Southern Ontario on Monday.
ONTARIO: Thunderstorm Forecast for Sunday, August 27, 2023
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Thunderstorms are currently not expected across Southern Ontario on Sunday.
ONTARIO: Thunderstorm Forecast for Friday, August 25, 2023
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Thunderstorms are currently not expected across Southern Ontario on Friday.
ONTARIO: Thunderstorm Forecast for Thursday, August 24, 2023
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For Southwestern Ontario, the rhythm of thunderstorms seems unending as the region experienced a relentless night of storm activity, delivering a soaking 100-200mm to Windsor and Essex County. Unfortunately, the storm saga continues, as a second day of potential severe weather awaits Southern Ontario on Thursday afternoon and evening.
Confidence is growing in what might shape up to be a potentially hazardous day, particularly in Deep Southwestern Ontario, with potential extensions into parts of the Golden Horseshoe. The stage is set for strong severe storms, with a favourable environment likely to unfold starting from the early afternoon hours.
Fresh data suggests that the overall storm threat could surpass initial expectations. In response, we've introduced a ‘significant’ severe risk zone specifically focused on Deep Southwestern Ontario. The reasons behind this upgrade include the threat of wind gusts reaching up to 120 km/h and an elevated tornado risk. While the primary concern revolves around the potential for destructive wind gusts, it's worth noting that the possibility of large hail up to the size of golf balls can't be dismissed, particularly within isolated early-day storms.
Key questions surround the precise location of storm initiation. Initial models indicated storms emerging over Michigan during the late afternoon hours and subsequently crossing into Southwestern Ontario by evening. However, the latest trends depict a line of storms developing from the Western GTA, extending through Kitchener and over Lake Huron.
As this evolving line of storms descends southward, it will encounter a prime environment over Southwestern Ontario, which may spur rapid intensification. Timing still holds a degree of uncertainty, with the possibility of storms being pushed to a later evening occurrence. However, this shift doesn't seem likely to influence the severity of the events.
Further storm development is also possible over Michigan, impacting Deep Southwestern Ontario. In this scenario, a wide-ranging complex of storms could sweep the region with robust damaging wind gusts spanning 100-120km/h, during the late evening into the early overnight hours. While the tornado and hail risk is anticipated to be more pronounced as storms initially form, the focus may later shift to a wind-driven threat as the day progresses. This variable risk hinges on the potential storm appearance over Michigan.
We've incorporated an ‘isolated strong tornado’ risk specifically for the Windsor and Chatham regions. This risk hinges on storm development in proximity to the border and their subsequent trajectory into Southwestern Ontario during the height of the tornado risk. In either case, the possibility of tornadoes remains a significant concern.
Amid these dynamics, the concern for flash flooding is in the spotlight, particularly in areas that witnessed substantial rainfall on Wednesday and Thursday morning. The prospect of an additional 50-100mm of precipitation further accentuates localized accumulation, potentially totalling 200-300mm within two days.
Moving beyond Deep Southwestern Ontario, the severe threat extends to portions of the Golden Horseshoe, including the Niagara and Hamilton regions, which have a ‘slight’ severe risk. Some data points to isolated storm development in the late afternoon and evening, possibly bringing in hail of ping pong ball size, wind gusts reaching 100 km/h, and the potential for an isolated tornado. As always, stay vigilant, keep an eye on updates, and stay safe.
ONTARIO: Thunderstorm Forecast for Thursday, August 24, 2023
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A second day of potential severe weather is in store for parts of Southern Ontario on Thursday. It's shaping up to be somewhat reminiscent of Wednesday's scenario, with Southwestern Ontario once again at the forefront of a strong severe risk. However, this time around, the storms are expected during the usual mid-day hours, a departure from the late-evening events experienced in Deep Southwestern Ontario on Wednesday night.
According to the latest data, a favourable environment for robust severe storms is projected to take shape starting from the early afternoon hours onwards. The focus lies on Deep Southwestern Ontario and along the Lake Huron shoreline.
With a reasonable level of confidence, we anticipate storm initiation during the afternoon to early evening timeframe. The exact location where these storms will intensify remains uncertain. The prevailing scenario suggests the likelihood of a sizable cluster of storms forming over Lower Michigan and traversing Lake Huron, making their way into Southwestern Ontario by late afternoon to early evening.
Alternatively, there's a possibility of isolated storm development over Lake Huron, resulting in fewer storms affecting Deep Southwestern Ontario. Indications also point to the potential for isolated storm formation ahead of the primary line, impacting inland regions including Kitchener, Hamilton, and possibly parts of the GTA.
Irrespective of the scenario, the atmospheric conditions will be conducive to storm activity capable of producing wind gusts of up to 110 km/h, hail the size of golf balls, and even one or two tornadoes. Flooding concerns remain prominent, especially given the recurrence of heavy rain for areas that received substantial rainfall on Wednesday. An additional 50-100mm of rainfall could contribute to localized accumulation approaching 200mm over the span of two days.
The most elevated risk area lies in Deep Southwestern Ontario and along the Lake Huron shoreline. This event is anticipated to unfold between 2 PM and 8 PM, with the possibility of storms extending into the later night hours. As the storm line advances southeastward, it may impact the Golden Horseshoe during the evening.
Consequently, there's an isolated to slight risk of severe weather forecasted for the Niagara, Hamilton, and Toronto regions. Our primary concern centers around potential damaging wind gusts, with hail and tornadoes becoming less likely as the storms progress eastward. Keep an eye on the sky and stay tuned for further updates.
ONTARIO: Thunderstorm Forecast for Wednesday, August 23, 2023
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As August winds down and cooler nights settle in across Southern Ontario, there's a noticeable touch of fall in the air, with some areas experiencing single-digit overnight temperatures. This shift to colder air also signifies the winding down of our primary severe thunderstorm season. While the risk of severe thunderstorms can persist into September and even October, historically, the most intense severe events tend to occur during the months of June, July, and August in our region.
However, there's no quiet exit in sight for summer just yet. The threat of severe thunderstorms is looming over parts of Southern Ontario for Wednesday and Thursday. The latest data indicates a potential storm threat in two separate waves over the next 48 hours.
The first wave is expected to develop late on Wednesday and continue into Thursday morning, bringing with it a potential risk of strong nocturnal storms in Deep Southwestern Ontario. A second severe risk is forecasted for Thursday afternoon and early evening, affecting a similar area as on Wednesday.
The overall weather pattern is intricate, with multiple elements in play. Bands of heavy rain are projected to develop across Central and Southwestern Ontario during Wednesday morning, resulting in a prolonged period of steady rainfall in the GTA and areas around Lake Huron and Georgian Bay. There's also the possibility of embedded thunderstorm activity within the band of precipitation.
Simultaneously, colder air will accompany the area of rain, leading to notable temperature differences across Southern Ontario. For instance, while the GTA and regions around Georgian Bay struggle to reach daytime highs in the mid-teens on Wednesday, the Ottawa Valley and Deep Southwestern Ontario are expected to enjoy temperatures ranging well into the mid to upper twenties.
In the southwestern part of the province, a pocket of significant instability is anticipated to form across Michigan and extend into Deep Southwestern Ontario by Wednesday evening. Models suggest that the line of ongoing precipitation will gradually shift southwestward and intensify as it taps into the more robust environment. By the late evening hours, this line of storms could potentially become quite intense as it moves through the London, Sarnia, Chatham, and Windsor region between 10 PM and 2 AM.
The overall storm risk is subject to some uncertainty primarily due to the timing of this event. If it were to occur a few hours earlier, it would likely fall within a significant severe risk based on the expected intense environmental conditions. While we have opted for a ‘strong’ severe risk due to the later timing. We can’t rule out a potential upgrade to ‘significant’ if our confidence grows in a more widespread event.
These late-night storms could potentially bring strong wind gusts of up to 110 km/h as the primary threat. Although large hail up to the size of ping pong balls is also possible, the linear nature of the storm may mitigate the likelihood of very large hail. The atmospheric conditions could also support the development of a few tornadoes, with the possibility of an isolated strong tornado.
In addition to the damaging wind threat, there's a notable risk of flash flooding on Wednesday. The slow movement of the storm line could result in prolonged heavy rainfall over specific areas, particularly in Southwestern Ontario, potentially leading to rainfall totals exceeding 100mm. Urban areas, which are more vulnerable to significant rainfall in short periods of time, could experience localized flooding.
Thunderstorm activity is expected to clear out of Southern Ontario by Thursday morning. Later on Thursday, the environmental conditions could allow for more storm development in Deep Southwestern Ontario during the afternoon and early evening. However, the models present varying scenarios, so we'll wait for the initial round of storms to unfold before focusing on the specifics of the second round. Keep an eye out for our forthcoming forecast for Thursday afternoon/evening!
ONTARIO: Thunderstorm Forecast for Tuesday, August 22, 2023
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Thunderstorms are currently not expected across Southern Ontario on Tuesday.
ONTARIO: Thunderstorm Forecast for Monday, August 21, 2023
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Thunderstorms are currently not expected across Southern Ontario on Monday.
ONTARIO: Thunderstorm Forecast for Sunday, August 20, 2023
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Thunderstorms are currently not expected across Southern Ontario on Sunday.
ONTARIO: Thunderstorm Forecast for Saturday, August 19, 2023
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Thunderstorms are currently not expected across Southern Ontario on Saturday.
ONTARIO: Thunderstorm Forecast for Friday, August 18, 2023
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Thunderstorms are currently not expected across Southern Ontario on Friday.
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.
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.
ONTARIO: Thunderstorm Forecast for Monday, August 14, 2023
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Thunderstorms are currently not expected across Southern 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.
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!
