We are currently watching the risk of scattered non-severe thunderstorms with multiple pockets of isolated severe thunderstorms.
Southern Ontario:
In Southern Ontario, we are watching the risk for some non-severe thunderstorms across portions of Central and Eastern Ontario. This is highlighted in blue and marked with a '1'. This area extends from Peterborough through to Bancroft and Pembroke and extends south to include Perth, Brockville, Kingston, and Belleville. This area also includes the Ontario-Quebec border from Mattawa south towards Petawawa. Most of this region will not see thunderstorms as we are only expecting a limited amount of isolated cells to develop. The main threats will be downpours and possibly small hail.
Further east into Far Eastern Ontario, we have highlighted an area of a 'low' severe risk. This is seen in green or marked with a '2'. This includes Arnprior and extends through to Smiths Falls and Prescott and includes everything east of this point. This includes Ottawa and Cornwall. The main threats in this region are moderate sized (1-2cm) hail, isolated gusty winds (70-90km/h) and downpours. There is also a non-zero tornado risk across this region. Similar to before, we are only expecting limited storms and isolated in nature. Not everyone in this region will see thunderstorms in general, let alone severe storms.
Quebec:
In Quebec, we are watching two areas of possible severe thunderstorms followed by a much larger area of non-severe thunderstorms. The non-severe thunderstorms are expected west of a line which extends from Sherbrooke through to Portneuf and Les Équerres extending to include Lac Beaucours and Lac Evens before entering James Bay. The main threats with these isolated non-severe thunderstorms will include small hail and downpours. This is highlighted in blue and marked with a '1'.
The first area of a 'low' risk of severe thunderstorms extends from Le Flash through Mont-Tremblant Park into Gatineau and Huntingdon regions. This is seen in green or marked with a '2'. This includes Montreal and Fort-Coulonge as well as Sabrevois. These thunderstorms are expected to remain isolated and limited in nature. Not everyone in this region will see a thunderstorm, let alone a severe storm. The main threats in this region are moderate sized (1-2cm) hail, isolated gusty winds (70-90km/h) and downpours. There is also a non-zero tornado risk across this region.
The second area of a 'low' risk of severe thunderstorms extends from Joutel and Lac Paul-Sauvé through to James Bay, this includes Fort-Rupert. This is seen in green or marked with a '2'. The thunderstorms will be more scattered than the southern regions but the risk of severe storms is lower. The main threats in this region include downpours and small to moderate sized hail. An isolated severe wind gust is possible. It is questionable whether any severe thunderstorms will develop in this area.
Northern Ontario:
In Northern Ontario, we are watching a few areas of possible severe thunderstorms followed by a much larger area of non-severe thunderstorms. Most of Northern Ontario has the risk of seeing thunderstorms today. The risk is mainly scattered and hence, not everyone will see thunderstorms. This is highlighted in blue and marked with a '1'.
The strongest non-severe thunderstorms will extend from Red Lake through to Wabakimi Park and down to the Carmat and Hornepayne regions including the Kenora, Fort Frances, and Dryden regions. These storms can expect small hail, heavy downpours and gusty winds between 60-80km/h. Elsewhere, small hail and downpours can be expected. Repeated storms going over the region could produce 25-50mm of rain as well. Across this region, there are also noticeable patches where an isolated landspout tornado could form due to different winds in the atmosphere causing some weak ground rotation compared to the sky. These areas are highlighted by the 'area of interest'.
There is some question about whether or not an area between English River and Manitouwadge could see an isolated severe thunderstorm. We have gone against this and have not included this area in a 'low' risk area.
This same situation includes an area from Matheson through to Chapleau and than down to Temiskaming Shores. There is a low risk for severe thunderstorms, but, this is questionable and hence, not included in the 'low' severe risk thunderstorm area. This area is included in a non-zero tornado risk if an isolated severe thunderstorm does decide to develop across this region. Despite this low tornado risk, it's still too low to include in the next level up on the scale.
The first area of a 'low' risk of severe thunderstorms extends Agawa Bay through to Ranger Lake and Spanish including everything west of this line. This is seen in green or marked with a '2'. This includes Sault Ste. Marie and portions of Manitoulin Island. There is the risk of a few isolated thunderstorms developing and forming a small cluster of cells. These thunderstorms will move southeast towards Manitoulin Island and Lake Huron before weakening. This could produce some isolated severe thunderstorms with winds around 90km/h, small hail, and heavy downpours. If the storms develop and remain isolated, there is a non-zero tornado threat.
The second area of a 'low' risk of severe thunderstorms extends from Kesagami Park through Onakawana and into James Bay, this includes Moosonee. This is seen in green or marked with a '2'. The thunderstorms will be more scattered than the southern regions but the risk of severe storms is lower. The main threats in this region include downpours and small to moderate sized hail. An isolated severe wind gust is possible. It is questionable whether any severe thunderstorms will develop in this area.
Southern Manitoba
In Southern Manitoba, scattered showers and thunderstorms are likely to develop across the province. The thunderstorms will likely be isolated and limited in nature, therefore, not everyone will see thunderstorms. Across the 'area of interest,' an isolated severe thunderstorm may be possible across the region.
The main threats will any storm in Manitoba today would include small hail, downpours and possibly an isolated severe wind gust. A landspout tornado can't be ruled out within the 'area of interest.'