Canada: Severe weather forecast across southeastern regions through at least Aug. 20 /update 1

Severe weather is forecast across parts of southeastern Canada through at least Aug. 20. A low-pressure trough is expected to bring heavy rainfall and scattered thunderstorms across the region. Strong wind gusts, lightning, and hail may accompany storms. Rainfall totals of around 4-8 cm (1.6-3.1 inches) are expected across the affected areas. The downpours may trigger flooding in low-lying areas and ponding on road surfaces.

Environment Canada has issued red heavy rainfall warnings (the highest level on a three-tier scale) for parts of east-central Nova Scotia and southeastern and southwestern Quebec. Grey special weather statements are in place for parts of northern New Brunswick and southern Quebec. 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 or mountainous areas, especially where heavy rain has saturated the soil. Disruptions to electricity and telecommunications services are possible where significant flooding, landslides, or strong winds impact utility networks.

Floodwaters and debris flows could render some bridges, rail networks, or roadways impassable, impacting overland travel 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 could also trigger intermittent flight delays and cancellations at regional airports, though these are unlikely to be severe or prolonged. 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 may occur in low-lying areas.