Friday will be a day of transition across most of Alberta with the southern half of the province expecting temperatures in the high teens, and rain transitioning to snow around the Capital region. Strong wind is expected across most of Alberta – including Calgary, where sustained wind speeds of 20 to 40 km/h are likely with gusts over 40 km/h. A cold air mass will bring a quick change in temperatures and amplify the effects of that moisture-laden system situated east to west over the northern edge of the Rockies. Heavy rain is forecast for areas along the Yellowhead Highway in B.C. and Alberta and extending into Saskatchewan. As of 8 a.m. Friday, rain was already starting to transition to snow in the higher elevations along the Alberta-B.C. border north of the Rockies, and in locations where temperatures were close to freezing. A yellow-level snowfall warning was issued for the west-central portion of Alberta, with Environment and Climate Change Canada (ECCC) saying significant snowfall us expected over west-central Alberta Friday and Saturday. “Rainfall will change over to snow through the day (Friday) as temperatures drop. Accumulating snow will be confined to higher elevations during the (day), but will become widespread by this evening.” There is little model agreement on how much snow will fall or where the heaviest accumulations will be, with the national weather agency saying snowfall amounts will be “highly variable, ranging from about seven cm to 25 cm.” The most likely scenario is that locations that are in protected valleys and lower terrain, such as the townsites of Jasper, Grande Prairie and Valleyview, will see snowfall totals at the lower end of this range. “Areas of higher terrain and northeast facing slopes, such as Highway 40 between Grande Prairie and Hinton, will see snowfall amounts at the higher end of this range,” ECCC said. That low-pressure system from northern Alberta will track south along the foothills on Saturday and is expected to impact central Alberta by the middle of the day. Major highways, including the QEII, are expected to experience periods of poor driving conditions from the precipitation. Strong wind will complicated matters by limiting visibility at times, and with temperatures expected to peak just above freezing, some surfaces could become icy and/or slushy. Calgary is not expecting significant precipitation accumulations, and may stay warm enough to avoid snow – but rain is likely Friday afternoon or evening, and there is a chance of some mixed precipitation and/or snow. In their special weather statement issued for most of the province outside of the snowfall warning, ECCC said snow will move southwards Saturday night and continue to affect areas south of Calgary on Sunday. “At this time, only light snow is expected in Calgary and areas to its east, but more significant snowfall may occur against the Southern Alberta foothills as well as in locations south of Calgary.” Regardless of the amount of precipitation that falls over Calgary, it will be cold. After reaching the daytime high of 19 C on Friday, the temperature will fall to around 2 C overnight, and that will essentially be the warmest value until Monday. Overnight lows will drop below freezing this weekend in Calgary, with temperatures starting to moderate by early next week. Daytime highs will range from 9 to 14 C from Monday through Friday. The normal high in Calgary this time of year is 14 C.
