More rain expected in southern Alberta on Tuesday

Intense thunderstorms rolled through southern Alberta on Monday, producing damaging hail and strong winds.

According to Environment and Climate Change Canada (ECCC), baseball-sized hailstones fell in the hamlet of of Queenstown, tennis-ball sized hail fell near Mossleigh, egg-sized hail fell in Calgary and Cochrane, golf ball-size hail in Lyalta and Strathmore, ping pong ball-sized hail fell in Lake Louise, Toonie-sized hail fell in Delacour and nickel-sized hail fell in Okotoks.

Winds were also very strong with ECCC reporting peak gusts of 100 km/h near Tilley, 93 km/h near Mossleigh and 89 km/h in Diamond Valley.

Unusually large rainfall amounts also fell.

Public data on the ECCC forecast page for Calgary shows 52.7 mm of rain fell on Monday (that does not include rainfall accumulations after midnight).

This appears to be a record amount of precipitation for Calgary for Aug. 5, the next highest total for that day was 29 mm in 1962.

Radar from Monday, Aug. 5, 2024. (Note: the lightning layer has been removed to show the precipitation.) Instability will remain an issue for Tuesday, with scattered showers and thunderstorms forecast for southern Alberta – including in Calgary.

Rainfall totals will be much lower though, around five to seven millimetres for Calgary, with higher totals south of the city.

As of 7:30 a.m. Tuesday, there were no storm-related watches or warnings for Alberta. However, there is the potential for large storms to develop along the southern border of the province on Tuesday and into Wednesday.

Daytime highs will remain below seasonal to start the week before gradually improving by the end of the week. However, even with the improvement, in Calgary the maximum temperatures will remain below the seasonal average of 24 C.