ONTARIO: Thunderstorm Forecast for Monday, June 19, 2023

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FORECAST DISCUSSION

Thunderstorms are currently not expected across Southern Ontario on Monday.

ONTARIO: Thunderstorm Forecast for Sunday, June 18, 2023

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FORECAST DISCUSSION

Localized non-severe thunderstorms are possible in the Ottawa Valley during the late afternoon and evening on Sunday. These storms are expected to be weak, but they could bring some small hail, gusty winds and heavy rainfall.

NORTHERN ONTARIO: Thunderstorm Forecast for Sunday, June 18, 2023

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FORECAST DISCUSSION

Isolated thunderstorms are expected to develop in Northwestern Ontario during the afternoon and evening on Sunday. These storms should remain non-severe with small hail, gusty winds and heavy rainfall. Although, there is a slight chance that we may see funnel clouds which in rare cases can touch down and become a landspout tornado. This risk is questionable at best as the environment isn’t that strong but still worthwhile to mention.

ONTARIO: Thunderstorm Forecast for Saturday, June 17, 2023

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FORECAST DISCUSSION

Thunderstorms are currently not expected across Southern Ontario on Saturday.

NORTHERN ONTARIO: Thunderstorm Forecast for Saturday, June 17, 2023

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FORECAST DISCUSSION

Thunderstorms are currently not expected across Northern Ontario on Saturday.

ONTARIO: Thunderstorm Forecast for Friday, June 16, 2023

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FORECAST DISCUSSION

Widespread non-severe thunderstorms are expected throughout Central and Eastern Ontario along with the Golden Horseshoe on Friday. The highest concentration of storms is expected to be in Eastern Ontario along the St. Lawrence River although we may see some isolated storms further west around the GTA and Central Ontario.

The current model data suggest that the environment is quite favourable for the development of funnel clouds with these storms during the afternoon and evening. While funnel clouds don’t usually pose a threat, 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.

NORTHERN ONTARIO: Thunderstorm Forecast for Friday, June 16, 2023

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FORECAST DISCUSSION

Thunderstorms are currently not expected across Northern Ontario on Friday.

ONTARIO: Thunderstorm Forecast for Thursday, June 15, 2023

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FORECAST DISCUSSION

There is the potential for strong thunderstorms over Deep Southwestern Ontario this Thursday afternoon and evening, particularly impacting areas such as Windsor, Leamington, and Chatham.

The current data indicate that a series of discrete storms, potentially developing into supercells, are likely to form in Southeastern Michigan near Detroit, moving towards Southwestern Ontario around dinner time. With the strong environmental conditions, these storms pose significant threats, including hail up to the size of golf balls and wind gusts reaching 100 km/h. A tornado threat is also associated with these storms, as detailed further below.

This severe weather threat will predominantly be localized to Deep Southwestern Ontario, with a slight risk extending from Sarnia to St. Thomas. An isolated severe storm might also occur as far north as Grand Bend, Woodstock, and Brantford. Meanwhile, non-severe but sporadic thunderstorms could affect other parts of Southern Ontario, but not everyone will witness these storms.

TORNADO RISK

Tornado potential, particularly in the Windsor, Leamington, and Chatham regions, is another concern we're closely monitoring. These areas, with the strongest environmental conditions, could see one or two tornadoes primarily during the late afternoon and early evening hours. An isolated tornado risk also includes the rest of Deep Southwestern Ontario, encompassing areas like Sarnia and London.

In more northern regions, like the Golden Horseshoe and Eastern Ontario, there are some signs that the environment could support funnel cloud development. These funnel clouds typically don't touch the ground but there's a slim chance they could touch down and become landspout tornadoes. However, this largely depends on whether storms will even materialize in these regions to exploit the given environmental conditions.

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.

NORTHERN ONTARIO: Thunderstorm Forecast for Thursday, June 15, 2023

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FORECAST DISCUSSION

Thunderstorms are currently not expected across Northern Ontario on Thursday.

ONTARIO: Thunderstorm Forecast for Wednesday, June 14, 2023

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FORECAST DISCUSSION

There is a risk of non-severe thunderstorms across much of Southern Ontario on Wednesday. While these storms should be fairly weak, the environment is favourable for the development of funnel clouds which in rare cases may touch the ground and become a landspout tornado. The only exception is Southwestern Ontario which isn’t expected to see any thunderstorm activity.

NORTHERN ONTARIO: Thunderstorm Forecast for Wednesday, June 14, 2023

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FORECAST DISCUSSION

Thunderstorms are currently not expected across Northern Ontario on Wednesday.

NORTHERN ONTARIO: Thunderstorm Forecast for Tuesday, June 13, 2023

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FORECAST DISCUSSION

Non-severe thunderstorms are expected to linger into Tuesday morning in areas north of Georgian Bay. A second round of storms could develop towards the evening and affect areas in the northern part of Northeastern Ontario around Kapuskasing and Moosonee.

ONTARIO: Thunderstorm Forecast for Tuesday, June 13, 2023

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FORECAST DISCUSSION

The potential for non-severe thunderstorms will carry over from Monday evening into the early hours of Tuesday across Eastern and Central Ontario. Isolated storms are also possible in Deep Southwestern Ontario as we head into the late afternoon and evening hours.

Based on the latest data, the environment is favourable for a few of these storms to reach severe levels with sizable hail and strong wind gusts. There is also the potential for 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 Monday, June 12, 2023

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FORECAST DISCUSSION

Scattered non-severe thunderstorms are possible in Central and Eastern Ontario on Monday. This is courtesy of a system currently bringing bands of heavy rainfall to the region which could also include embedded thunderstorms. The thunderstorm activity will be more widespread towards the evening and into early Tuesday morning.

NORTHERN ONTARIO: Thunderstorm Forecast for Monday, June 12, 2023

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FORECAST DISCUSSION

Scattered non-severe thunderstorms are possible in Northeastern Ontario on Monday. This is courtesy of a system currently bringing bands of heavy rainfall to the region which could also include embedded thunderstorms. The thunderstorm activity will be more widespread towards the evening and into early Tuesday morning.

ONTARIO: Thunderstorm Forecast for Sunday, June 11, 2023

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FORECAST DISCUSSION

A system is expected to bring well-needed heavy rainfall to Southern Ontario starting Sunday afternoon and continuing into Monday. Within the cluster of rain, we could see some pockets of non-severe thunderstorms predominantly during the late afternoon and evening hours. We don’t expect they’ll be that strong but can still produce frequent lightning strikes and very heavy rainfall. A separate forecast focused on the rainfall over the next few days will be released on Sunday.

ONTARIO: Thunderstorm Forecast for Saturday, June 10, 2023

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This afternoon, parts of Central and Eastern Ontario may see the development of a few isolated thunderstorms. Current atmospheric conditions are favourable for these storms to intensify, potentially reaching severe levels with large hail and damaging wind gusts. Our primary concern for severe activity is focused on an area that includes Barry’s Bay, Bancroft, Renfrew, Pembroke, and Cloyne.

Based on the latest data, models are suggesting that an isolated cell may form around Algonquin Park and Barry’s Bay by late afternoon, approximately between 3-5 PM. This cell is projected to move slowly southeastward and could generate toonie-sized hail, wind gusts of up to 100km/h, and heavy rainfall.

Elsewhere in Eastern and Central Ontario, we may see some pop-up storms, which are likely to remain non-severe. However, there is a possibility of isolated severe storms stretching into the Smiths Falls and Brockville areas.

TORNADO RISK

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While the risk is low, we cannot rule out the possibility of an isolated tornado if a storm develops in this region this afternoon to take advantage of the environment. The highest potential for a tornado is during the initial phase of the storms, putting locations including Barry’s Bay, Eganville, and Cloyne squarely in the potential risk zone.

Moreover, there's a wider possibility for funnel clouds and perhaps even a landspout tornado (a tornado not associated with a supercell) across Central and Eastern Ontario.

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 Saturday, June 10, 2023

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Localized thunderstorms are possible in Eastern Ontario on Saturday. Current indications suggest that an isolated severe risk could exist in the Bancroft, Pembroke, Renfrew and Tweed regions. The main risk with these storms will be nickel-sized hail, 90km/h wind gusts along with some heavy rain in excess of 50mm. Important to note that not everyone will see those significant rainfall totals as these storms will be extremely localized.