A slight shift in the upper patterns has introduced instability across portions of Alberta. Cooler air, stronger wind, and rain impacted northern Alberta early Thursday as a low-pressure system began to move northwest to southeast into central Saskatchewan. The trailing cold front has brought more cloud cover and stronger wind into southern Alberta – including Calgary. Wildfire smoke – mainly from the fires in British Columbia – was noticeable in Calgary Thursday morning and was reaching concerning levels for the southwestern portion of Alberta. A yellow-level air quality warning was issued for areas along the southern foothills including Waterton Lakes National Park, Crowsnest Pass, and Pincher Creek. Yellow and orange-level air quality warnings were issued for most of the central and southern portions of B.C. including the Fraser Valley, the Okanagan, and Metro Vancouver. Drive BC cameras on Thursday morning appeared to show wildfire smoke along major highways including Highway 3, Highway 97A, Highway 5, and the TransCanada Highway.. As of 10:30 a.m. the Air Quality Health Index rating in Calgary was a 2, low-risk, but expected to reach a 4 (moderate risk) later in the day and overnight as eastern wind pushed wildfire smoke back against the foothills. Daytime highs across southern Alberta will increase to end the week, before dropping down to more seasonal values by the end of the weekend as the ridge of high-pressure that has been situated over the western portion of the country starts to flatten. Rain is possible later on Saturday in the corridor between Calgary and Edmonton, and pop-up showers and thunderstorms are likely overnight and early Sunday. With the current wildfire situation in British Columbia a long period of steady and intense rain would be ideal, however there does not seem to be any likelihood of that happening anytime soon. The start of next week will include daytime highs as low as 17 C in Calgary (compared to the average of 24 C). Intermittent and - at times – persistent rain is expected for the middle of next week with some forecast models suggesting between 10 to 15 millimetres on certain days.
