Trough keeps cool air over B.C., Alberta, brings thunderstorm threat

·4 min read
Trough keeps cool air over B.C., Alberta, brings thunderstorm threat
Trough keeps cool air over B.C., Alberta, brings thunderstorm threat
Trough keeps cool air over B.C., Alberta, brings thunderstorm threat

After featuring extreme temperatures throughout a good portion of the summer, Western Canada is in the midst of a cooling trend, thanks to a trough hanging over the region. It is also expected to bring some showers and thunderstorms Friday and Saturday, helping with the drought and wildfires in B.C., pushing out the associated smoke from the fires, as well. The threat for storms will extend into Alberta and Saskatchewan, too. Rainfall won't be too much, especially when compared to the projections for Manitoba and northwestern Ontario, but any is needed. More on the cooler temperatures and thunderstorm risk, and the latest on B.C.'s hazardous air quality from the wildfire smoke, below.


Instability and a broad upper-level trough over B.C. and Alberta Friday could bring showers and the threat for thunderstorms in parts of both provinces in the afternoon and evening. It also extends into Saskatchewan, where storms could also fire up.

Most of the storms should remain below severe criteria, but extreme southeastern Alberta may see potent cells develop, extending into southwestern Saskatchewan. The main hazards will be heavy rainfall, strong wind gusts and small hail.


Through Sunday, a good portion of western Alberta and the B.C. Interior will see 10-20 mm of rain, so not substantial by any means, but any amount will be helpful for the wildfires in the latter province.

Temperature-wise, the trough will keep temperatures on the cool side in B.C. Daytime highs Friday will be in the low- to mid-20s. Slightly cooler temperatures for Alberta, where most areas won't reach any higher than the upper teens.


On Saturday, a broad trough will set up a low-pressure system in northern B.C. that will move southward, sparking more convection in the Interior, bringing the threat for thunderstorms in the afternoon once again.

Some could potentially become severe in parts of the northern and southern areas. The main hazards include heavy rainfall, strong wind gusts and small hail.


Meanwhile, Alberta may also see the risk of thunderstorms, as the low-pressure system moves east from B.C. Most of the threat will be confined to areas west of Calgary, along the foothills and B.C. border. Most are expected to remain non-severe in nature, but some could reach warning criteria in central and northwestern sections.

Temperatures will be a bit warmer in B.C. Saturday, with some areas in the central and southern Interior hovering closer to the mid-20s, but still remaining below seasonal.

Daytime highs in Alberta will be below seasonal still, though slightly warmer than Friday, with temperatures possibly reaching the 20-degree mark in some areas in the western sections.


Ongoing wildfires across the B.C. Interior means the hazardous air quality, especially for communities near large wildfires, will continue. Special air quality statements remain in place.

"Stay inside if you have breathing difficulties. Find an indoor place that's cool and ventilated. Using an air conditioner that cools and filters air may help. If you open the windows you may let in more polluted air. If your home isn't air-conditioned, consider going to a public place that is air-conditioned," Environment and Climate Change Canada says in the alert.

BC Wildfire Service
BC Wildfire Service

(BC Wildfire Service)

As of Friday morning, there are more than 250 fires active across the province, mostly in the Interior. The fire danger remains at "high" or "extreme" levels in southern Vancouver Island and in parts of the central Interior still.


The cooler pattern will continue through next week for B.C. and Alberta.

For the former, scattered showers will move into southern areas on Sunday with more widespread rain for central and northern sections. Beyond the weekend, dry conditions return with several days of mostly sunny and pleasant weather for early and mid-week. There is potential for showers late week, but no major storms in sight at this point.

As well, another low is expected to develop over Alberta on Sunday and then move east across the Prairies Monday and Tuesday with widespread rain. With those cooler temperatures, we'll be keeping an eye on snow for the northern Rockies from Sunday into Monday night -- stretching from northern B.C. into the northern foothills in Alberta.

Additional unsettled weather is possible late week.

Stay tuned to The Weather Network for the latest on conditions across British Columbia and Alberta.

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