Canada: Severe weather forecast over parts of southern British Columbia, Alberta, and southwestern Saskatchewan late Aug. 23

Thunderstorms are forecast across parts of southern British Columbia, southern Alberta, and southwestern Saskatchewan as of late Aug. 23. Heavy downpours, strong winds, lightning, hail, and tornadoes may accompany storms. Environment Canada has issued a red rainfall warning (the highest level on a three-tier scale) for parts of Metro Vancouver and Fraser Valley in British Columbia, and red severe thunderstorm warnings from the border of British Columbia over Calgary to near Standard in Alberta, and from Springwater East stretching over Saskatoon and Swift Current to the international border at Grasslands National Park in Saskatchewan. Yellow severe thunderstorm watches are in place across the rest of the affected area. Authorities will likely issue new alerts or update/rescind existing advisories as weather conditions change over the coming hours.

Sustained heavy rainfall could trigger flooding in low-lying communities near rivers, streams, and creeks. Urban flooding is also possible in developed areas with easily overwhelmed stormwater drainage systems. Sites downstream from large reservoirs or rivers may be subject to flash flooding after relatively short periods of intense rainfall. Landslides are possible in hilly areas, especially where heavy rain has saturated the soil.

The severe weather could contribute to transport disruptions throughout the region. Floodwaters and debris flows may render some bridges, rail networks, or roadways impassable, impacting overland travel in and around affected areas. Ponding on road surfaces could cause hazardous driving conditions on regional highways. Authorities could temporarily close some low-lying routes that become inundated by floodwaters.

Severe weather may trigger flight delays and cancellations at airports across the affected region. Flooding could block regional rail lines; freight and passenger train delays and cancellations are possible in areas with heavy rainfall and potential track inundation.

Localized business disruptions could occur in flood-hit areas; some businesses might not operate at full capacity because of damage to facilities, possible evacuations, and some employees' inability to reach work sites. Strong winds could also cause power outages.