Severe thunderstorms with double tornado risk target Edmonton region Saturday, July 18

Severe thunderstorms with a double tornado risk are targeting the Edmonton region on Saturday, July 18, according to Environment and Climate Change Canada.

The Storm Prediction Centre describes conditions as "potentially explosive," with atmospheric instability measurements (MLCAPE values) of 3000+ J/KG—nearly unprecedented for Alberta. The main threat will coincide with the intersection of a dryline and cold front, with tornadic potential maximized in the northeast quadrant.

An extreme-risk zone extends just east of Edmonton toward the Saskatchewan border, where wind gusts could reach 130 kilometres an hour, hail could grow to 7 centimetres (baseball-sized), and a higher-end tornado risk exists.

A moderate-risk zone encompasses Edmonton, Spruce Grove, St. Albert, Leduc, Devon, and Drayton Valley, with wind gusts up to 120 kilometres an hour, hail up to 6 centimetres (tennis ball-sized), a tornado risk, and potential rainfall up to 75 millimetres.

Environment Canada advised close monitoring this afternoon, noting that storms forming in this pattern have historically been associated with long-track, tornadic supercells. The risk continues into overnight hours Sunday with a minor risk for most of the province, though a moderate risk touches Lloydminster.