Tag: Torrential Downpours

Manitoba

Powerful Line of Storms Threaten Damaging Winds in Manitoba

Temperatures are set to surge near the 30 degree mark today in Southern Manitoba, once the humidity is factored in it will feel closer to 40 degrees celsius. Relief will come in the form of thunderstorms; atmospheric conditions will be primed for severe weather.

A potent system will track eastwards out of Saskatchewan into Manitoba this afternoon acting as a trigger for severe thunderstorms. Strong southwesterly winds aloft will overspread southeasterly winds at the surface; a summer-time signal the atmosphere is primed to produce severe thunderstorms.

Lets play out how storm evolution will likely occur today.

[Valid 4pm] In this model projection, we see ongoing storms in Southeastern Saskatchewan. Manitoba still largely remains thunderstorm free – until the forcing for ascent arrives and the capping inversion erodes.


[Valid 7pm] Explosive thunderstorm development follows around the dinner hour across Southwestern Manitoba; including Brandon, Neepawa, Morden, and Portage. Quickly growing into a large line of severe thunderstorms that will produce damaging winds up to 110km/h, 3-5cm hail, torrential rainfall, frequent lightning, and the risk of a tornado.

[Valid 10pm] an expansive line of windstorms will progress throughout Southeastern Manitoba. Likely clipping the Ontario/Manitoba border. This severe complex could become a powerful, long-track Mesoscale Convective Complex (MCS); as it transverses North Dakota & Minnesota through the overnight hours.


Note the triple-point – an axis of intersection between a warm, cold and occluded front. South of this intersection point (warm front), storm energy will likely build to a very-unstable value nearing 4000J/Kg. This is the region that will be watching for the potential of a tornado. The risk may continue into southeastern Manitoba through the late evening.

Environment Canada Thunderstorm Outlook valid today. Noting an ‘Extreme Risk’ for Severe Thunderstorms. Navigate to their forecast here.
Ontario

Thunderstorms Threaten Damaging Winds in Southern Ontario

A sudden surge of warm, summer-like air will herald in the risk of thunderstorms across the Lower Great Lakes. These thunderstorms may turn severe; capable of producing damaging winds & hail across portions of Southern Ontario. 

SURGING TEMPERATURES, THUNDERSTORMS & RAIN

An area of low-pressure will transverse through the Midwestern United States towards Ontario, throughout the day Sunday. Ahead of the system, temperatures will surge into the mid-20s and humidity readings into the low-30s. Near the Lake-shore, cooler conditions are expected.

Showers are expected before midnight tonight, lasting into the pre-dawn hours. Persistent rain-showers and embedded thunderstorms are expected for Central Ontario – mainly East of Georgian Bay. Sunny breaks are anticipated through the morning hours, allowing for some instability to build before the arrival of a cold front.

A soaking rainfall and single-digit temperatures North of the warm front. Heavy thunderstorms ahead & along a cold front in the South.

At this point, it appears the setup will feature two potential waves of thunderstorms. The primary wave will consist of a complex of heavy rain showers with embedded thunderstorms impacting Southern Ontario between 4-10 pm. Initiating at approximately 4 pm in Windsor and exiting Eastern Ontario by 11 pm. Risks include: torrential downpours, lighting and isolated damaging winds. A potentially stronger second round of thunderstorms (along an advancing cold front) may happen on Sunday evening/overnight, across Extreme Southwestern Ontario. There is some uncertainty regarding the evolution of thunderstorm development. If thunderstorms do develop, risk factors include: hail and isolated damaging wind gusts.

Across Northern Ontario, a large swath of heavy rainfall is expected. Local rainfall totals nearing 50mm is anticipated.

Ontario

Severe Thunderstorm Risk; Brief Cool-Down; Another Blast of Heat…

Conditions will become favourable for the development of severe thunderstorms for a large area across Southwestern, Southern, Central and Eastern Ontario for Thursday, July 5th.

What to Expect
With continued rising temperatures, high dew-points, and daytime heating, a weak front will slice through the aforementioned regions and provide enough instability to bring-about some severe thunderstorms later in the day on Thursday.

While the dynamics are not entirely conducive to significant supercell development, a lack of shear, ultimately, will mitigate rapid intensification and development. The primary risk therefore, with these thunderstorms, will be quick flooding rains (25-50mm).

The greatest threat for severe thunderstorms will likely occur just east of Lake Huron, but likely 15-20km west of the major 401 corridor. The GTA and QEW should remain non-severe (overall) and regions around Cottage Country should receive rain showers.

1 or 2 severe thunderstorms on the northern edge of Lake Ontario cannot be ruled out.

Cool-Down
A brief / slight cool-down (24-27C; less humid; and drier conditions), will arrive for the aforementioned regions on/for Friday, Saturday and Sunday.

What’s Next?
From te brief cool-down outlined above, temperatures are expected to rebound back into the upper 20s and low 30s for the next severel weeks (avg: 29-32C). This time around however, conditions will be less humid than the more recent surge of warmth.

As outlined in our summer prediction, isolated severe thunderstorms will continue across Ontario and Quebec for much of the summer.

Long-Range Outlook: Manitoba, Ontario and Quebec.
Continued above normal temperatures and relatively dry conditions are still expected for Manitoba, Ontario and Quebec. There is some potential for record-breaking heat once again somewhere in the last few days of July into early August for about a week.

Remember, summer thunderstorm forecasts  – severe and/or non-severe – represent a plausible scenario based on extensive weather calculations, parameters and up-to-date atmospheric data. Nothing is for certain, but outlines a possible or likely scenario based on the aforementioned points.

Please stay tuned, as we at TCW are monitoring this situation attentively.

Drive safe and always be alert during hazardous conditions.

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