There is the potential for thunderstorms throughout parts of Southern Ontario on Sunday. However, the confidence in this event is low at this time and the exact location is unclear.
Thunderstorm activity that has brought significant severe weather to parts of Northwestern Ontario during the day on Friday will continue to track eastward overnight and into early Saturday morning. This line of storms should be non-severe for the most part as it affects Northeastern Ontario throughout the morning although a few isolated pockets of damaging wind gusts can’t be ruled out mainly during the early morning.
A secondary risk of storms is expected for Northeastern Ontario during the afternoon and evening on Saturday. This risk could bring the potential for a few isolated storms in an area that stretches from the eastern shoreline of Lake Superior and northward towards James Bay. Main threats with these storms include some moderate-sized hail and damaging wind gusts along with significant rainfall totals ranging from 25-50mm. The storms will come to an end after sunset once they move out over Quebec and out of Northern Ontario.
There is the potential for thunderstorms throughout parts of Northern Ontario on Saturday. However, the confidence in this event is low at this time and the exact location is unclear.
Thunderstorms are currently not expected in the forecasted region on this day.
There is the potential for significant severe storms through parts of Northwestern Ontario during the afternoon and evening on Friday. The environment is favourable for some quite powerful storms to develop near the Manitoba border northeast of the Kenora area. We’re currently targeting the Red Lake, Dryden and Sioux Lookout corridor for the strongest severe potential but this may shift around a bit depending on how early in the day that we see storm development.
Some models have storms development further east closer to the Armstrong area, but right now we are going with the more western risk zone. These storms include the risk for some very large hail (perhaps golf ball size or even larger), destructive wind gusts over 110km/h and heavy rainfall. There is also the potential for several tornadoes and maybe even an isolated significant tornado somewhere in Northwestern Ontario as outlined in the tornado risk zone on our map.
The storms will continue to track eastward throughout the evening hour bringing the threat of severe weather as far east as Thunder Bay and Geraldton although the main threat will shift towards damaging wind risk. The tornado threat will be mainly during the afternoon and early evening hours, but still can’t rule out an isolated tornado even outside the main risk zone. We should see the severe risk come to an end by midnight although strong non-severe storms will continue into the overnight hours.
Environment Canada has forecasted a "High" risk in orange, which is a 3 out 4 on their threat level scale and highlighted in orange on their forecast map. This risk comes with the potential for isolated tornadoes, 90-120km/h damaging wind gusts, and 2-7cm damaging hail.
Today is a good day to have a plan and pay attention to any severe weather alerts issued for your area. To receive alerts the instant they're issued, download our free mobile app Instant Weather by clicking this link: InstantWeather.ca/app and/or click here for Apple or Android.
Below is what Environment Canada wrote in their forecast. Something to note, their forecast is extremely technical so we've included the important items that are easiest to understand. If you'd like to read the full scientific forecast, we have included it further down the page:
"Significant Weather Discussion...
...Low pressure crossing Saskatchewan today should serve as trigger for severe thunderstorm development this afternoon through this evening, and into the overnight hours for Manitoba...
...Supercell development seems very likely this afternoon, with large hail... perhaps up to baseball size... and damaging wind gusts to 120 km/h associated with the strongest storms.
...Furthermore, strongly veering wind profiles in the lower levels support a tornado risk with any storms that develop in a locally favourable environment...
... Severe storms should be able to continue throughout the night as they move through Manitoba, although the severe threat should end over southern Manitoba with the loss of daytime heating. The tornadic threat should likewise diminish sharply after sunset..."
For those wondering, these "prototype" maps are not yet available on EC's website. However, they are posted on Environment Canada's twitter account at @ECCCWeatherSK. These forecasts and maps are issued by the same Environment Canada meteorologists that issue all Watches and Warnings for Saskatchewan. They're also temporarily hosted by the University of Manitoba here:
https://umanitoba.ca/faculties/environment/envirogeog/weather/conv_otlk/
If you're interested in the full scientific forecast, here it is:
"SIGNIFICANT WEATHER DISCUSSION ISSUED BY THE PRAIRIE AND ARCTIC STORM PREDICTION CENTRE OF ENVIRONMENT CANADA AT 7:00 AM CDT THURSDAY JULY 22 2021.
ALERTS IN EFFECT...SPECIAL AIR QUALITY STATEMENTS OUT FOR MUCH OF MANITOBA, PARTS OF SASKATCHEWAN AND PARTS OF ALBERTA.
SYNOPTIC OVERVIEW...UPPER LOW NEARING THE ALBERTA ELBOW WITH SURFACE TROUGH FROM NE ALBERTA TO SW SASKATCHEWAN.
DISCUSSION...
EASTERN PRAIRIES...TROUGH OF LOW PRESSURE CROSSING SK TODAY SHOULD SERVE AS TRIGGER FOR SEVERE THUNDERSTORM DEVELOPMENT THIS AFTERNOON THROUGH THIS EVENING, AND INTO THE OVERNIGHT HOURS FOR MANITOBA. SURFACE ANALYSIS SHOWING PLENTIFUL MOISTURE, WITH DEWPOINTS OF 18-20 OVERNIGHT AND A LARGE AREA OF STRATUS DEVELOPING AS SEEN ON SATELLITE IMAGERY INDICATING DEEP MOISTURE. COOLING ALOFT AS UPPER LOW DRIFTS EASTWARD COMBINED WITH DAYTIME HIGHS AROUND 30 DESTABILIZE THINGS THIS AFTERNOON, WITH PROGGED SBCAPE VALUES IN THE 1500-2500 J/KG RANGE IN AN ENVIRONMENT WITH 40-50 KNOTS SHEAR. GIVEN THESE INGREDIENTS SUPERCELL DEVELOPMENT SEEMS VERY LIKELY THIS AFTERNOON, WITH LARGE HAIL...PERHAPS UP TO BASEBALL SIZE...AND DAMAGING WIND GUSTS TO 120 KM/H ASSOCIATED WITH THE STRONGEST STORMS. TRANSVERSE BANDING DENOTING JET STREAK NOTED ON WATER VAPOUR IMAGERY EARLY THIS MORNING IN SOUTHERN MONTANA WHICH SHOULD MORE INTO SOUTHERN SK THIS AFTERNOON GIVING ADDITIONAL UPPER SUPPORT/LIFT. FURTHERMORE, STRONGLY VEERING WIND PROFILES IN THE LOWER LEVELS SUPPORT A TORNADO RISK WITH ANY STORMS THAT DEVELOP IN A LOCALLY FAVOURABLE ENVIRONMENT.
GIVEN FAVOURABLE JET DYNAMICS, SHEAR, AND THE LOW LEVEL JET FEEDING INTO THE DEVELOPING LOW, SEVERE STORMS SHOULD BE ABLE TO CONTINUE THROUGHOUT THE NIGHT AS THEY MOVE THROUGH MANITOBA, ALTHOUGH THE SEVERE THREAT SHOULD END OVER SOUTHERN MANITOBA WITH THE LOSS OF DAYTIME HEATING. THE TORNADIC THREAT SHOULD LIKEWISE DIMINISH SHARPLY AFTER SUNSET.
WESTERN PRAIRIES/NWT...HIGH PM2.5 VALUES REPORTED NEAR CANMORE AND CAROLINE. WILL SEE HOW THE SMOKE LOOKS WHEN DAYTIME SATELLITE IMAGES COME IN THIS MORNING BUT SOME POTENTIAL FOR THE SMOKE TO EXPAND NEAR CALGARY. DEPENDING ON HOW THE SMOKE LOOKS THUNDERSTORM FORECASTS WILL LIKELY BE ADJUSTED ON THE MORNING UPDATE.
GOOD AREA OF PVA IN SOUTH CENTRAL BC TO MOVE INTO CENTRAL ALBERTA THIS AFTERNOON TRIGGERING THUNDERSTORMS. BY THE AFTERNOON THE 500 JET RUNS FROM YYC-YCT-WJH AROUND 60 KNOTS. MOISTURE EXPECTED TO POOL SLIGHTLY NORTH OF CALGARY WITH MLCAPES ALONG THAT AXIS NEAR 1500 J/KG. STORMS WILL LIKELY TRIGGER EARLY WITH THE COLD 500 MB TROUGH MOVING IN. STORMS ARE LIKELY TO BE SEVERE WITH 2 TO 4 CM HAIL AND STRONG WINDS AS THE MAIN THREATS. SMOKE WILL HAVE TO BE MONITORED AS THE SVR RISK AREA IS NEAR THE CURRENT AREA OF HIGH PM VALUES.
THUNDERSTORMS THAT DEVELOP NEAR GREAT SLAVE LAKE THIS AFTERNOON WILL BE NEAR THE UPPER LOW AND VERY SLOW MOVING. SLIGHT RISK OF FUNNEL CLOUDS AS WELL AS HEAVY RAIN IN THE AREA.
EASTERN ARCTIC..NIL SIG WX.
END/FULTON/WIELKI"
More details ASAP!
There is the potential for thunderstorms throughout parts of Northwestern Ontario on Friday. However, the confidence in this event is low at this time and the exact location is unclear.
A few thunderstorms may affect regions along the Quebec border in Northeastern Ontario along with Northwestern Ontario around the US border. Although storms aren’t expected to be widespread enough to require a forecast.
A cluster of non-severe thunderstorms may develop over Southern Quebec during the afternoon on Thursday and track into parts of Central and Eastern Ontario around the Quebec border by the evening. These storms won’t be particularly strong and shouldn’t pose much of a threat aside from some small hail, strong wind gusts, heavy rainfall and lightning. The thunderstorm threat will come to an end by late evening.
Thunderstorms are currently not expected in the forecasted region on this day.
Thunderstorms are currently not expected in the forecasted region on this day.
Thunderstorms are currently not expected in the forecasted region on this day.
There is a widespread risk of severe storms across Southern Ontario on Tuesday. A cold front will sweep across the province and may spark off a line of storms along the front starting during the early afternoon across Georgian Bay and northern parts of Central Ontario. It will move to the southeast during the afternoon bringing the potential for severe weather with strong wind gusts being the main threat although we could see some localized pockets of large hail if there are some isolated pop-up storms ahead of the main line of storms. Flash flooding could also be an issue as we’re seeing some indications of ‘training’ storms developing through parts of the GTA that are very susceptible to heavy rainfall within a short timeframe.
Compared to our previous forecast, the risk has become much more widespread and we’ve added a severe risk zone to parts of Central, Eastern and Southwestern Ontario along with the GTA and Niagara Region. Most of Southern Ontario has at least an isolated risk of severe storms, but keep in mind that not everyone will see the storms on Tuesday. Also, there is some disagreement in the data which means confidence in this forecast isn’t as high as we normally are the night before an event. Adjustment may need to be made by Tuesday early afternoon so check back for that.
As for the tornado risk, it isn’t super strong and nowhere near the level that we saw on Thursday, but we can’t rule out the potential for one or two tornadoes. The main risk zone from tornadoes includes much of the Golden Horseshoe, to the northwest into Orangeville, north through Lake Simcoe and eastward along the northern Lake Ontario shoreline. It’s possible we may see tornadoes outside of this zone as it isn’t really focused on a particular region and we had to be broad with the risk zone.
Thunderstorm development is possible across Southern Ontario during the afternoon and evening on Tuesday. A few of these storms could beomce severe in a zone stretching from Owen Sound to Lake Simcoe and along the northern shoreline of Lake Ontario. Large hail, damaging wind gusts and heavy rainfall will be the main threats with these storms although an isolated tornado can’t be ruled out.
Right now, the tornado risk isn’t clear so we’re waiting until the next forecast update to pinpoint any tornado risk if it still exsits. As we get closer to the event the isolated severe risk zone may change and we may even have to introduce a severe risk zone if the storm risk becomes stronger. We’ll have more details with our final forecast on Monday evening.
Thunderstorms are currently not expected in the forecasted region on this day.
Widespread thunderstorm activity is expected to develop across Northern Ontario during the afternoon on Monday. There is the potential for a few of these storms to become severe for locations such as Thunder Bay, Kapuskasing and Timmins. The main risks with these storms will be large hail, damaging wind gusts and flash flooding. An even stronger risk for severe storms exists through parts of Northeastern Ontario along the Quebec border including Timmins, Cochrane, Temiskaming Shores and Kapuskasing.
In this area, one or two tornadoes can’t be ruled out in addition to the damaging wind gusts and large hail. The latest models show a few isolated supercells developing near Kapuskasing during the late evening and track southeastward through the aforementioned region before crossing into Quebec. The storm threat will come to an end just after midnight.
There is the potential for thunderstorms throughout parts of Southern Ontario on Tuesday. However, the confidence in this event is low at this time and the exact location is unclear.
There is the potential for thunderstorms throughout parts of Northern Ontario on Monday. However, the confidence in this event is low at this time and the exact location is unclear.
A few isolated thunderstorms may develop across parts of Northern Ontario during the afternoon and evening on Sunday. The strongest chance for storms is to the north of Georgian Bay through Sudbury and North Bay. Any storms that develop should remain non-severe with small hail, strong wind gusts and heavy rainfall. The storm threat will come to an end by late evening.
Isolated slow-moving thunderstorms are expected to develop across Eastern, Central and Northeastern Ontario during the afternoon on Sunday. These storms will be mainly non-severe, but some localized flooding could be an issue especially to the northeast of the GTA. They’ll be moving very slowly and could ‘train’ over an area for several hours bringing between 50-100mm of rain. Small hail and strong wind gusts are also possible. The storm risk will come to an end by the late evening.
