Tag: nocturnal thunderstorms

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.
Alberta

Severe Weather Envelopes the Southwestern Prairies Thursday; Reloads Friday

A potent upper-air pattern will create extreme instability across the Southwestern Prairies Thursday. A surface trough will slice through the summer air offering a trigger for explosive thunderstorm development in the unstable atmosphere.

Winds at the surface out of the southeast and upper-level winds from the southwest suggest a well-sheared warm sector. The strongest surface heating will remain just south of the border. In spite of that, ample moisture delivery, temperatures falling aloft, effective shear, and plenty of energy will provide a breeding grounding for severe thunderstorms Thursday.

Thunderstorms will develop across Southern Alberta and Northern Montana around 2 pm. Trans-versing northeastwards throughout the afternoon and evening, Initial storm develop may feature discrete cells and bowing segments; a threat for large hail, damaging winds, and an isolated tornado is possible. As progression into the evening continues, a powerful nocturnal complex of thunderstorms known as a Mesoscale Convective Complex (MCS), may develop. These convective weather systems are notorious producers of damaging winds, intense frequent lightning, large hail, and localized flooding in torrential downpours. Moreover, these systems are known to persist well into the pre-dawn hours.

click to navigate forecast map.

HAZARDS: 90-110km/h wind gusts, 2-5cm hail, torrential rainfall, frequent lightning, and an isolated tornado.

We will be monitoring the thunderstorms throughout Saskatchewan and Alberta attentively on Thursday. Be sure to closely monitor watches and warnings throughout the afternoon, evening and overnight. We will be issuing another forecast for severe thunderstorm risk in Saskatchewan, Friday. The risk depends greatly on the evolution of thunderstorms Thursday into pre-dawn Friday.

HEAVY RAINFALL CONTINUES WEST OF EDMONTON

Much of the focus is rightfully centered around substantial thunderstorm risk further south, but appreciable rainfall amounts along the Highway 16 & 40 corridor is worth mentioning. This region has already seen very-heavy rainfall over the last several days. Another 50-75mm is on tap between Hinton and Edmonton, through Friday.