NORTHERN ONTARIO: Thunderstorm Forecast for Friday, June 9, 2023

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Scattered thunderstorms are expected to develop across Northwestern Ontario on Friday. A few of these storms have the potential to become severe with the main risks being 90+ km/h wind gusts and quarter-sized hail. There could also be a risk of funnel clouds which in rare cases can touch down and become a landspout tornado.

Landspout: A landspout is a type of tornado that forms under a weak thunderstorm. Unlike traditional tornadoes, which develop from supercell thunderstorms and are associated with a rotating updraft called a mesocyclone, landspouts form from non-supercell storms and do not have a mesocyclone. These tornadoes are generally weaker and shorter-lived than their supercell counterparts but can still pose a threat to property and life, with wind speeds occasionally reaching up to 160 km/h.

ONTARIO: Thunderstorm Forecast for Friday, June 9, 2023

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Isolated pop-up thunderstorms are possible for a second day in Central and Eastern Ontario on Friday. The risk for these non-severe storms will be primarily focused during the afternoon and early evening hours. These storms will be very localized and not everyone within the risk area will see rain (as many are hoping for rain to help with very dry conditions).

The highest wildfire threat is in Southwestern Ontario which is mostly outside the zone we expect to see the storm threat. Thus, the risk of new fires being started by lightning should be low, but can’t be ruled out.

ONTARIO: Thunderstorm Forecast for Thursday, June 8, 2023

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Isolated pop-up thunderstorms are possible during the afternoon and early evening on Thursday across Southern Ontario. While these storms are expected to be quite weak, they could still produce the occasional lightning strike which could potentially start new wildfires. There are also some indications that the environment is favourable for the development of funnel clouds. Especially around the shoreline of Lake Ontario and Erie. Funnel clouds usually don’t present a risk, but in rare cases, they could touch down and become a landspout tornado.

Landspout: A landspout is a type of tornado that forms under a weak thunderstorm. Unlike traditional tornadoes, which develop from supercell thunderstorms and are associated with a rotating updraft called a mesocyclone, landspouts form from non-supercell storms and do not have a mesocyclone. These tornadoes are generally weaker and shorter-lived than their supercell counterparts but can still pose a threat to property and life, with wind speeds occasionally reaching up to 160 km/h.

Upcoming Wildfire Smoke Poses Serious Air Quality Risks for Southern Ontario

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While we've seen some marginal improvement in air quality this evening as surface-level smoke dissipates, Southern Ontario isn't out of the woods just yet. An extensive plume of smoke is shifting our way and is expected to affect the region overnight and into early Wednesday.

Current data suggest that this incoming wave of smoke could degrade air quality even further than what we witnessed today. Petawawa is already feeling the impact with an Air Quality Index (AQI) of 430, a level significantly above the "very hazardous" category. In fact, Petawawa currently has some of the worst air quality globally, excluding specific regions in South America and India.

This severe air quality is what we anticipate waking up to on Wednesday. Models suggest the heaviest smoke concentration will target Eastern and Central Ontario, although the Greater Toronto Area (GTA) may also face thick smoke. While less smoke is expected in the southwest, air quality remains a concern across the region.

While we predict some respite later on Wednesday, brace for the arrival of an even more intense smoke plume on Thursday, potentially affecting the GTA and Southwestern Ontario. The severity of this situation is unprecedented, making it difficult to predict the exact level of impact.

Many locations across Southern Ontario may report the worst air quality in recorded history, and the pollutants in the air could pose a critical threat to those exposed for extended periods. We recommend staying indoors as much as possible over the next couple of days, especially during the early part of Wednesday and Thursday. This is a serious health concern, regardless of pre-existing conditions.

Looking ahead, a shift in wind direction over the weekend might provide a temporary respite, but the potential for more smoke next week remains, depending on fire activities.

At Instant Weather, we are committed to providing regular updates on active wildfires, smoke, and air quality across Southern Ontario. Please continue checking our updates for crucial information in the coming days.

ONTARIO: Thunderstorm Forecast for Tuesday, June 6, 2023

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Pop-up thunderstorms are yet again expected in parts of Eastern Ontario around the Ottawa Valley during the afternoon on Tuesday. As we saw on Monday, the main risk will be the lightning that could lead to more wildfires. Otherwise, these storms are expected to remain non-severe.

ONTARIO: Thunderstorm Forecast for Monday, June 5, 2023

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Isolated pop-up thunderstorms are possible in Eastern and Central Ontario during the afternoon and evening on Monday. While these storms are expected to remain non-severe, the biggest threat will be the lightning combined with very dry conditions that may lead to additional wildfires. And due to the localized nature of these storms, we don’t expect they will put much of a dent in the fire risk situation across the region.

NORTHERN ONTARIO: Thunderstorm Forecast for Sunday, June 4, 2023

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Thunderstorms are possible in Northwestern Ontario on Sunday afternoon and evening. The best chance for storms is from Kenora through Dryden and into Thunder Bay. A few of these storms around Kenora, Red Lake, Drydent and Sioux Lookout could reach isolated severe levels with large hail and damaging wind gusts. The environment isn’t favourable for a tornado risk, but keep in mind that any thunderstorm has the potential to strike and produce a tornado.

NORTHERN ONTARIO: Thunderstorm Forecast for Saturday, June 3, 2023

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Non-severe thunderstorms are possible in Northwestern Ontario on Saturday. The best chance for storms is right along the Manitoba border.

ONTARIO: Thunderstorm Forecast for Friday, June 2, 2023

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THURSDAY PM UPDATE: The latest data remains consistent with our preliminary forecast from Wednesday. We have expanded the non-severe thunderstorm risk into the GTA. The ‘isolated’ severe risk zone is more for the flash flooding potential due to the slow-moving nature of these storms. If we see large hail, damaging wind gusts and maybe even a tornado it will be likely east of Ottawa where a few supercells can’t be ruled out.

After a very long break from thunderstorm activity in Southern Ontario, that streak is about to end with the potential risk for severe storms in Central and Eastern Ontario on Friday.

We expect to see the development of isolated pop-up thunderstorms across Central Ontario during the afternoon into the early evening. While most of these storms should remain non-severe, we have gone with an isolated severe risk as these storms will be moving quite slowly and could present a flash flooding threat. Could also see some small hail and strong wind gusts.

Some of the latest model data suggest that there could be a fairly strong severe threat in Extreme Eastern Ontario in the Cornwall area to the east of Ottawa. Models are showing an intense cluster of storms developing over Quebec by the late afternoon and sinking southward into Eastern Ontario. We believe the potential exists for up to 100 km/h wind gusts and quarter-sized hail. An isolated tornado can’t be ruled out either.

NORTHERN ONTARIO: Thunderstorm Forecast for Thursday, June 1, 2023

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Isolated severe thunderstorms are possible stretching from Fort Frances through Thunder Bay and into parts of Northeastern Ontario on Thursday. Storms are expected to develop during the early afternoon hours and slowly track to the southeast throughout the rest of the afternoon into the evening.

While they should be non-severe for the most part, there is the potential for a few storms to bring marginally severe hail and wind gusts. An isolated tornado can’t be ruled out but the overall risk is fairly low.