ONTARIO: Thunderstorm Forecast for Sunday, July 30, 2023
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Thunderstorms are currently not expected across Southern Ontario on Sunday.
GOOGLE AD (NOT ENDORSED BY INSTANT WEATHER)
NORTHERN ONTARIO: Thunderstorm Forecast for Sunday, July 30, 2023
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There is an isolated risk of severe weather in Northern Ontario on Sunday afternoon into the evening hours. The risk zone stretches from Temiskaming Shores through Chapleau, Wawa and into Armstrong. Several isolated storms are expected to develop and will eventually merge into a line of storms later in the day. These storms could present severe risks including toonie-sized hail, 90 km/h wind gusts and heavy rainfall. An isolated tornado can’t be ruled out.
ONTARIO: Thunderstorm Forecast for Saturday, July 29, 2023
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Non-severe thunderstorms are possible across Southwestern Ontario and into the Golden Horseshoe on Saturday. This risk is primarily during the morning and early afternoon with it diminishing later in the day.
NORTHERN ONTARIO: Thunderstorm Forecast for Saturday, July 29, 2023
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Thunderstorms are currently not expected across Northern Ontario on Saturday.
ONTARIO: Thunderstorm Forecast for Friday, July 28, 2023
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FORECAST DISCUSSION
After a brief respite from the stormy skies on Thursday, we're closely monitoring the reemergence of severe thunderstorms for parts of Southwestern, Central and Eastern Ontario on Friday.
Central and Eastern Ontario, particularly the Ottawa Valley, will take the early spotlight as the afternoon and early evening present the perfect environment for isolated supercells. The exact location of storm initiation is unclear but could start as far west as Muskoka and Simcoe County by the early afternoon.
These storms will continue to track eastwards into Eastern Ontario where the environment is only expected to get stronger throughout the day. In light of this, we've gone with a 'significant' severe risk, encompassing Renfrew, Ottawa, and the eastern regions like Cornwall. Our main concern is the potential for an isolated strong tornado due to the potent atmospheric conditions. Additionally, large hail up to the size of golf balls and wind gusts surpassing 100 km/h are other possible threats.
Keep in mind that the risk in Central and Eastern Ontario will be very isolated. We anticipate only a few scattered storms, with most locations within our severe risk forecast likely remaining untouched. As always, the actual risk hinges on storm development taking advantage of the expected environmental factors.
Meanwhile, Southwestern Ontario remains a key area of focus, echoing the recurring pattern of strong severe thunderstorm risks over the past weeks. Models indicate the potential for yet another widespread damaging wind threat, originating from Michigan and crossing into our region. The timing, as always, holds the key to the actual risk on our side of the border.
Earlier in the evening, around dinner time, there are signs of a few isolated storms popping up over Lake Huron and southward into Sarnia and Windsor. These initial storms could present all severe hazards, ranging from hail up to ping pong ball-sized, 100 km/h wind gusts, and one or two tornadoes.
As the night progresses, a mature line of strong to severe storms is expected to impact Deep Southwestern Ontario between 10 PM to 1 AM. The strength of this squall line remains uncertain due to the event's timing, though it does appear more likely to pose a damaging wind gust threat, with localized pockets potentially reaching 110-115 km/h. Additionally, an isolated tornado can't be ruled out.
Further northward development ahead of the line could bring an isolated severe threat to areas around Kincardine and Lake Simcoe during the evening hours. As the line of storms tracks eastward along Lake Erie, it will impact the GTA with the potential for severe wind gusts lingering past midnight.
Localized flash flooding could also be an issue in both Eastern and Southwestern Ontario. This is because we expected rainfall totals could potentially exceed 100mm in localized areas that see multiple rounds of storms.
NORTHERN ONTARIO: Thunderstorm Forecast for Friday, July 28, 2023
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FORECAST DISCUSSION
Thunderstorms are currently not expected across Northern Ontario on Friday.
ONTARIO: Thunderstorm Forecast for Thursday, July 27, 2023
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FORECAST DISCUSSION
Thunderstorms are currently not expected across Southern Ontario on Thursday.
NORTHERN ONTARIO: Thunderstorm Forecast for Thursday, July 27, 2023
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FORECAST DISCUSSION
Thunderstorms are currently not expected across Northern Ontario on DAY.
ONTARIO: Thunderstorm Forecast for Wednesday, July 26, 2023
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FORECAST DISCUSSION
A striking sense of déjà vu sweeps over Southwestern Ontario as we face yet another significant severe threat on Wednesday. While this severe risk differs from last week's ‘extreme’ severe risk and will likely be a lot weaker, it could still pack a punch. The hail risk appears less prominent this time, with expected sizes ranging from toonie to ping pong balls, a departure from the baseball-sized hail we saw on Thursday. However, the tornado risk could be similar to last week with an isolated strong tornado risk. Widespread destructive wind gusts are also possible, and models suggest the potential for severe winds extending eastward into the GTA and Niagara region through the evening.
Our localized 'significant' risk target focuses on the Windsor, Leamington, and Chatham regions. An explosive environment combined with storms forming during the dinner hour heightens the danger. Yet, some model discrepancies in storm mode and timing add an air of uncertainty. If the storms appear earlier, they will have a stronger environment to work with while a later arrival would lessen the threat. It looks like a strong squall line of storms will develop over Michigan and track into Southwestern Ontario sometime between 6 - 10 PM.
It’s important to note that there are hints of a potential ‘bust’ with some models showing storms not developing at all or arriving way too late. This forecast is conditional on storm development. We can say the environment is capable to produce these storm threats but it requires a storm to realize these threats. We are hoping that storms don’t develop as this could get quite nasty if they do show up!
🔴 Significant Severe Risk for Deep Southwestern Ontario (Windsor, Leamington, Chatham):
115 km/h wind gusts
Hail up to the size of ping pong balls
Isolated strong tornado risk
Severe threat starts as early as 5 PM and grows by the hour before peaking around 7 - 10 PM. It should diminish by midnight.
🟠 Strong Severe Risk for the Rest of Southwestern Ontario (Sarnia, London, Lake Huron shoreline):
100 km/h wind gusts
Hail up to the size of toonies
One or two tornadoes
Severe threat starts as early as 5 PM and grows by the hour before peaking around 8 - 11 PM. It should diminish by midnight.
As with last week, the extent of storm progression into Ontario remains uncertain, contingent on timing. Nonetheless, the Kitchener-Waterloo, Greater Toronto and Hamilton Area, and Niagara region might face a severe threat later in the evening. At this point, the primary concern will be damaging wind gusts, with tornado and hail risks slightly diminished but not entirely out of the question.
Isolated storms are also possible this afternoon and evening across Central and Eastern Ontario. We have extended the isolated severe risk into this region to account for the pop-up storms possible later in the day.
Moreover, we have serious concerns over flash flooding potential. Model projections indicate some areas might encounter multiple rounds of thunderstorms within a 6-12 hour window, leading to localized rainfall totals exceeding 100mm, possibly even reaching 150-200mm. While not all areas will experience such deluge, urban centers prone to flooding could face significant issues if struck.
We continue to go over the data and will provide an updated forecast by early Wednesday afternoon in case of any last-minute data changes. Stay tuned! Remain weather-aware throughout tomorrow as we brace for potentially ‘grumpy’ conditions.
Intense storms over Central Manitoba are expected to move into Northwestern Ontario on Wednesday evening. These storms could be very severe with hail up to the size of golf balls, 100 km/h wind gusts and one or two tornadoes. The storm risk will diminish after midnight as these storms slowly weaken while tracking to the east. Isolated severe storms are also possible north of Georgian Bay around the Sudbury and North Bay region.
NORTHERN ONTARIO: Thunderstorm Forecast for Wednesday, July 26, 2023
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FORECAST DISCUSSION
Intense storms over Central Manitoba are expected to move into Northwestern Ontario on Wednesday evening. These storms could be very severe with hail up to the size of golf balls, 100 km/h wind gusts and one or two tornadoes. The storm risk will diminish after midnight as these storms slowly weaken while tracking to the east. Isolated severe storms are also possible north of Georgian Bay around the Sudbury and North Bay region.
ONTARIO: Thunderstorm Forecast for Wednesday, July 26, 2023
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FORECAST DISCUSSION
Wednesday is shaping to be a potentially active day as indications point towards a strong severe risk across Southwestern Ontario during the late afternoon and evening hours. A potent environment is expected to develop, creating favourable conditions for severe weather.
Current models are suggesting the formation of a line of intense thunderstorms during the afternoon over Lower Michigan, which will track toward Southwestern Ontario by the evening. Unfortunately, this echoes last week's significant severe weather event, and areas hardest hit then are currently at the highest risk again. The exact timing of these storms will play a crucial role in the overall severe threat on our side of the border.
Presently, we are leaning towards a strong severe risk, stretching along the Lake Huron shoreline and southward into London, Sarnia, Chatham, and Windsor. As we gain more clarity on timing, the likelihood of introducing a 'significant' severe risk in this area is quite high. The severe threat could carry as far east as the GTA and Niagara region although that is questionable.
⚠️ Potential Threats
Destructive Wind Gusts: Expect the potential for widespread wind damage.
Very Large Hail: Hailstones of considerable size may cause damage to property and vehicles.
Flash Flooding: A major concern with localized rainfall totals of 100-150mm possible in a few hours.
Tornadoes: While uncertain, the environment may support a few tornadoes which is highly dependent on timing.
🕓 Timing
Southwestern Ontario: 6 - 10 PM
GTHA/Niagara: 8 PM - 12 AM
NOTE: This is a preliminary forecast and could change as we get closer to Wednesday. The forecast should only serve as a rough idea of potential threats and timing.
ONTARIO: Thunderstorm Forecast for Tuesday, July 25, 2023
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FORECAST DISCUSSION
A few pop-up thunderstorms may develop along the Lake Ontario shoreline from Kingston and through the Golden Horseshoe on Tuesday afternoon. One or two of these storms have the potential to become marginally severe with nickel-sized hail, 90 km/h wind gusts and heavy rainfall as the main threats. The strongest severe risk is in the west end of the GTA through Hamilton and Niagara region.
NORTHERN ONTARIO: Thunderstorm Forecast for Tuesday, July 25, 2023
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FORECAST DISCUSSION
Strong to severe thunderstorms are expected to develop over Central Manitoba during the afternoon on Tuesday and track into Northwestern Ontario by the evening. The highest risk for severe storms will be in the Red Lake, Dryden and Sioux Lookout areas where we have a slight severe risk. Threats include large hail up to the size of ping pong balls, 100 km/h wind gusts and localized flash flooding. An isolated tornado can’t be ruled out.
ONTARIO: Thunderstorm Forecast for Monday, July 24, 2023
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FORECAST DISCUSSION
On Monday afternoon and evening, widespread pop-up thunderstorm activity is on the horizon across Eastern and Central Ontario. The latest data indicates that the environment could support the development of some strong storms, bringing with them a slight severe risk, particularly in the Ottawa Valley region. There is also an isolated severe risk extending into the GTA and parts of Southwestern Ontario from Orangeville through K/W and into St. Thomas.
⛈️ Potential Threats
Hail: Hailstones up to the size of toonies could be possible, posing a risk to vehicles and properties.
Wind Gusts: Be prepared for gusts reaching up to 100 km/h, which may result in tree damage and power disruptions.
Heavy Rainfall: Localized downpours could lead to significant rainfall totals, ranging from 50-75mm within just a few hours.
🌪️ Tornado Potential
An isolated tornado can’t be ruled out although the risk is fairly low. There is also the possibility of funnel clouds developing with these storms. In rare cases, funnel clouds may touch down and become landspout tornadoes. If you spot a rotating cloud or funnel cloud, please take immediate precautions and seek shelter.
NORTHERN ONTARIO: Thunderstorm Forecast for Monday, July 24, 2023
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FORECAST DISCUSSION
Thunderstorms are currently not expected across Northern Ontario on Monday.
ONTARIO: Thunderstorm Forecast for Monday, July 24, 2023
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FORECAST DISCUSSION
Another day of pop-up thunderstorms is expected across Southern Ontario during Monday afternoon and evening. The primary focus for thunderstorm activity will be on Central and Eastern Ontario, stretching from Lake Simcoe to the east into the Ottawa Valley.
⛈️ Potential Threats
Some of these storms could pose marginally severe threats, including:
Hail: Up to quarter-size hail, which may cause damage to property and vehicles.
Wind Gusts: Wind gusts reaching 90 km/h, leading to the risk of tree damage and localized power outages.
Localized Flash Flooding: Heavy rainfall from the storms may result in localized flash flooding.
🌪️ Tornado Potential
While the overall tornado risk is low, we cannot completely rule out the possibility of funnel clouds developing. In rare cases, funnel clouds may touch down and become landspout tornadoes. If you spot a rotating cloud or funnel cloud, please take immediate precautions and seek shelter.
ONTARIO: Thunderstorm Forecast for Sunday, July 23, 2023
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FORECAST DISCUSSION
There is the risk of pop-up thunderstorms stretching from Southwestern Ontario into the Golden Horseshoe during the afternoon and early evening on Sunday. These storms should remain non-severe and relatively weak for the most part.
However, there is a chance that a few become marginally severe with up to quarter-sized hail, strong wind gusts and localized flash flooding being the main threat. The flood threat in particular could be a concern as these storms will be moving very slowly and may lead to locally significant rainfall totals in a short time frame. Additionally, there is also a questionable funnel cloud risk which in rare cases can lead to landspout tornadoes.
NORTHERN ONTARIO: Thunderstorm Forecast for Sunday, July 23, 2023
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FORECAST DISCUSSION
Widespread thunderstorm activity is expected across Northeastern Ontario on Sunday afternoon. A cluster of isolated storms will develop somewhere around Chapleau and track eastward throughout the rest of the afternoon into the early evening. These storms could feature isolated severe storms with all severe threats including large hail, damaging wind gusts and maybe even an isolated tornado.
ONTARIO: Thunderstorm Forecast for Saturday, July 22, 2023
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FORECAST DISCUSSION
Thunderstorms are currently not expected across Southern Ontario on Saturday.
NORTHERN ONTARIO: Thunderstorm Forecast for Saturday, July 22, 2023
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FORECAST DISCUSSION
Scattered thunderstorm activity is expected across Northwestern Ontario throughout the day on Saturday. A few of these storms could become marginally severe to the north of Thunder Bay including Sioux Lookout, Armstrong and Fort Hope primarily during the afternoon hours. Threats include 90 km/h wind gusts, quarter-sized hail and heavy rainfall. There is a slight chance of an isolated tornado but the risk isn’t overly strong.
