Southern Ontario: Thunderstorm Outlook for Thursday, July 8, 2021

/

Forecast Discussion

A line of heavy rainfall will track across Southern Ontario starting during the late morning on Thursday and continuing right through to the early evening. This line will also feature some embedded thunderstorms that could be quite strong with wind gusts and very heavy rainfall rates. Although these storms should remain non-severe. The risk will come to an end later in the day as the area of rain moves out of the province.

Southern Ontario: Thunderstorm Outlook for Wednesday, July 7, 2021

/
SON-TStorm-Day1.jpg

Forecast Discussion

An area of heavy rainfall with embedded non-severe thunderstorms is expected to track into parts of Southwestern Ontario and Central Ontario from Michigan overnight into Wednesday morning. Any thunderstorm will be quite weak, but widespread rainfall totals between 15-30mm and even up to 50mm for those that see thunderstorm activity is possible. So isolated flooding could be an issue especially since we’ve seen lots of rain over the past few weeks.

Later in the day, there could be some storms that develop through Extreme Southwestern Ontario. The environment is favourable for a few of these storms to reach severe levels with strong wind gusts and large hail possible. It doesn’t look like the tornado risk is particularly strong so we haven’t included it on the map, but keep in mind that it never is out of the question when we’re dealing with severe storms. Storms will weaken and move out of the region by midnight with potentially some non-severe thunderstorms and rain continuing overnight into Thursday.

Southern Ontario: Thunderstorm Outlook for Tuesday, July 6, 2021

/
SON-TStorm-Day1.jpg

Forecast Discussion

A few pop-up non-severe thunderstorms are possible along the northern Lake Erie shoreline during the afternoon and early evening on Tuesday. These storms will be extremly isolated so not all locations will see them. Current indicaqtions suggest that any storms that develop will move quite slowly so flash flooding could be an issue with 50+mm of rain in a short timeframe. Other threats include moderate-sized hail and strong wind gusts, but they should remain non-severe aside from the flooding risk. The storm threat will come to an end late in the evening as the storms fizzle out after sunset.

Northern Ontario: Thunderstorm Outlook for Monday, July 5, 2021

/
NON-TStorm-Day1.jpg

Forecast Discussion

There is a risk for severe thunderstorms throughout much of Northeastern Ontario during the afternoon and evening on Monday. The focus will be on regions just to the north of Georgian Bay where the strongest threat exists with even the potential for an isolated tornado.

Other parts of Northeastern Ontario along the Quebec border and northwards towards James Bay can expect a few isolated severe storms with strong wind gusts and moderate-sized hail as the main risk. The storm threat will come to an end late in the evening as the storms move out of the province and into Quebec.

Southern Ontario: Thunderstorm Outlook for Monday, July 5, 2021

/

Forecast Discussion

A very stormy start to the week is expected throughout Southern Ontario as hot, humid temperatures will lead to a fairly strong risk for thunderstorms with some of them reaching severe levels on Monday. The current target zone includes the shoreline around Georgian Bay and the northern parts of Lake Huron where we expect storms to develop sometime during the mid to late afternoon hours and track to the east or southeast.

This severe risk will also encompass the northern GTA and into parts of Central and Eastern Ontario with the main threat being damaging wind gusts over 100km/h as the line of mature storms sweeps across the region around the dinner hour. As for the tornado risk, it’s very questionable as the general storm mode favours more of a wind risk rather than tornadoes or large hail. Regardless, we’ve included a tornado risk on our map around Georgian Bay as there are some indications that a slight chance of a tornado or perhaps even a tornadic waterspout over Lake Huron or Georgian Bay that comes onshore is possible earlier in the lifespan of these storms.

The storm threat will continue late into the evening as the line of storms progresses into Eastern Ontario. It looks like the storms should weaken enough by midnight that they won’t pose a severe risk, but strong winds and heavy rainfall could continue to be an issue even into Extreme Eastern Ontario along the international border.

Northern Ontario: Thunderstorm Outlook for Sunday, July 4, 2021

/
NON-TStorm-Day1.jpg

Forecast Discussion

Non-severe thunderstorms are expected to develop along the Manitoba border and track into Northwestern Ontario during the late afternoon and evening hours on Sunday. The main threat with these storms will be strong wind gusts, small hail and heavy rainfall. All storm activity should come to an end by late evening.

Southern Ontario: Thunderstorm Outlook for Saturday, July 3, 2021

/

Forecast Discussion

A very small localized zone through Eastern Ontario extending from north of Lake Ontario through Peterborough/Bancroft and up into Pembroke along the Quebec border could see a few pop-up showers and maybe one or two non-severe thunderstorms during the afternoon on Saturday. These storms will quite weak and won’t pose much of a threat besides lightning and heavy rainfall. It will be extremely isolated so not every location within the risk zone will see rain or thunderstorms. The threat will come to an end by midnight.

Southern Ontario: Thunderstorm Outlook for Friday, July 2, 2021

/

Forecast Discussion

Scattered thunderstorms are yet again possible across parts of Eastern and Central Ontario along with the GTA during the day on Friday. These storms should be non-severe for the most part although some localized severe storms with moderate-size hail and flash flooding like we saw on Thursday can’t be ruled out. At this time, the risk isn’t strong enough or focused on a specific location for us to introduce an isolated severe risk zone. All storm activity should come to an end quickly after sunset.

Southern Ontario: Thunderstorm Outlook for Thursday, July 1, 2021

/

Forecast Discussion

Non-severe isolated pop-up thunderstorms are possible throughout Central, Eastern, Extreme Southwestern Ontario and around the GTA/Niagara region during the afternoon and evening on Thursday. These storms will be extremely isolated and not everyone will see them. Locations that do see the storms could be dealing with some flash flooding as there is the potential that these slow-moving storms could ‘train’ over a region for hours bringing 50-100mm locally. Other risks include strong wind gusts, small hail and frequent lightning strikes. Rain with embedded thunderstorms could continue into the overnight hours for Eastern and Central Ontario.

Southern Ontario: Thunderstorm Outlook for Wednesday, June 30, 2021

/
SON-TStorm-Day1.jpg

Forecast Discussion

Isolated non-severe thunderstorms are possible during the afternoon and early evening on Wednesday from Northeastern Ontario and into Eastern Ontario. Another zone for some storms that are more questionable exists from the GTA and along the Lake Erie shoreline. The main risk will be strong wind gusts, heavy rainfall and some small hail. The storms should quickly weaken after sunset.

Northern Ontario: Thunderstorm Outlook for Tuesday, June 29, 2021

/
NON-TStorm-Day1.jpg

Forecast Discussion

Isolated non-severe thunderstorms are possible across parts of Northern Ontario stretching from Thunder Bay through Kapuskasing and along the Quebec border during the day on Thursday. These storms will be quite weak and some might not be even strong enough to produce lightning. A few still could produce strong wind gusts, small hail and torrential downpours. The storm threat will come to an end just after midnight.

Strong Severe Risk Including Tornadoes Possible for Parts of Southern Ontario on Tuesday (June 29)

/

Forecast Discussion

There is a fairly strong risk for severe thunderstorms on Tuesday throughout parts of Southwestern, Central and Eastern Ontario along with the GTA. The first round of storms will come in the morning which should be mainly non-severe. There is a questionable morning severe risk along the Lake Huron shoreline with damaging wind gusts, moderate-sized hail and heavy rainfall.

The main story will come later in the day as several isolated storms are expected to pop up in a zone stretching from Lake Huron through Lake Simcoe just to the north of the GTA sometime during the afternoon. The environment is favourable for any storm that develops to quickly become severe with damaging wind gusts, large hail and heavy rainfall.

There is also the potential for one or two tornadoes with the strongest storms although it’s not guaranteed. The biggest tornado threat exists through Simcoe County and around the Lake Huron shoreline. Wouldn’t be out of the question to see a waterspout develop over Lake Huron or Georgian Bay and come on land somewhere in the above-mentioned region.

We’ll see the mature storms track eastward as they move into the GTA and through Eastern Ontario north of Lake Ontario during the late afternoon and early evening hours. The main threat later in the evening will be strong wind gusts as the tornado risk diminishes and the storms will fully move out of the region by the early overnight hours.

Northern Ontario: Thunderstorm Outlook for Monday, June 28, 2021

/

Forecast Discussion

Isolated thunderstorms are expected to develop during the day on Monday in parts of Northern Ontario stretching from Kenora through Thunder Bay and up into the Cochrane/Moosonee region. These storms should remain non-severe with heavy rain, strong wind gusts and small hail. The risk will come to an end by the late evening as any lingering storms will quickly weaken and dissipate.