Friday could be the most active night of weather for the summer so far. A powerful low-pressure system in south-central B.C. is pushing our way, and Calgary is shaping up to be right in the line of fire of some hazardous weather that could bring 90 km/h winds, two-to-five-centimetre-diameter hail and localized rain amounts of 25 to 50 millimetres. It’s going to be an evening to protect, secure or remove any items exposed to the elements that could be damaged or at risk of blowing away and harming someone or something. The main timeframe of the most severe weather will likely be between the hours of 7 p.m. and 12 a.m., with the storm dissipating around 3 a.m. Saturday. The rest of Saturday morning will be calm and relatively clear, but that allows for surface heating like we saw today, with the warm rising air creating another round of instability for tomorrow afternoon and into the evening. Sunday, the thunderstorm risk is reduced, but we will still remain under a very large trough of low pressure that will continue to circulate clouds and rain over southern Alberta throughout the rest of the weekend, with more sustained cloud coverage and rainfall into the first few days of next week. All this instability will keep our temperatures below seasonal, with the lowest temperature of the five-day forecast on Tuesday—a high of just 14 C. We finally start to see a shift in this wet weather pattern on Wednesday, with the sun returning back into the forecast, warming us up back into seasonal territory.
