Wednesday will be the coolest day for the next week and include weather conditions similar to Tuesday with periods of sun and cloud, stronger north and northwest wind and scattered showers and thunderstorms. The daytime highs in southern Alberta will sit in the low double-digits Wednesday, compared to the seasonal average of 17 C in Calgary. Sustained wind speeds in Calgary will range from 30 km/h to 50 km/h with gusts stronger than that. The main weather-maker is a “lee-side low,” a low-pressure system that forms on the leeward side of a mountain range (or in this case the eastern slopes of the Rockies). An incoming ridge of high pressure behind it is forcing that low to track east rather than sit along the foothills. This means precipitation will be more widespread and continue to follow the path of that low rather than produce pockets of rapid accumulation if the low were to remain stationary east of the range. Areas south of Calgary and north of Highway 3 could see rainfall totals of over 10 millimetres today, whereas Calgary is expecting around one to two millimetres in communities that do get rain. Mild thunderstorms will likely develop in southern and eastern Alberta by the afternoon and evening and could include small-sized hail and/or weak funnel clouds, especially north and east of Red Deer. Starting Thursday, that incoming ridge will introduce some stability and warmer air for the end of the week. Daytime highs are expected to sit in the low to mid-20s in Calgary from Friday until Tuesday, with overnight night lows ranging from 8 C to 11 C. The average low in Calgary this time of year is 4 C.
