Canada: Adverse weather forecast across parts of western Ontario June 18

Severe weather is forecast over parts of western Ontario June 18. Thunderstorms and heavy rainfall are forecast across the region; storms may be accompanied by strong wind gusts, lightning, hail, and possible tornadoes. Heavy downpours could trigger flooding in low-lying areas, and strong winds could cause property damage and power outages. Authorities have warned people in the affected area to take cover if threatening weather approaches.

Environment Canada has issued a yellow severe thunderstorm watch (the middle level on a three-tier scale) across areas along the border with Minnesota in the US due to a line of thunderstorms moving northward into the region early June 18. Winds gusting up to 90 kph (56 mph), large hail, and locally heavy rainfall are expected in the affected area. A grey special weather statement for heavy rainfall due to slow-moving thunderstorms is also in place across much of the affected area. Rainfall totals of 4-8 cm (1.6-3.1 inches), with localized higher amounts, are expected in the region through June 18. Officials will likely issue further weather alerts, including possible tornado warnings, in the region 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 located 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 rainfall has saturated the soil.

Authorities could issue mandatory evacuation orders for flood-prone communities over the coming hours. Disruptions to electricity and telecommunications services are possible where significant flooding or landslides impact utility networks.

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.