The next 24 to 36 hours will serve as a classic example of the highly variable and rapidly evolving weather conditions possible across southern Alberta. Temperatures early Wednesday were normal around the Calgary area, sitting close to -2 C with a mild wind and no precipitation. But, as the day progresses, a series of small disturbances will encounter a larger low-pressure system expected to form near Calgary, all of which will enhance the impact from both. Overnight, there were scattered lightning strikes across the region with more possible later in the day once that low forms near Calgary and the risk of instability increases. Fast wind speeds within the exit region of this trough (the eastern side of the counterclockwise rotation around the low) will only enhance the effects of the scenario. Strong north winds at the surface will limit visibility, especially in areas with persistent snowfall, and it is likely that narrow bands of snow will form. These synoptic situations make it very difficult to pinpoint precipitation totals per location as the Rockies serve as a physical barrier, but it is possible that portions of east-central and southern Alberta could see at least 30 centimetres of snow by the time this event is over Thursday night. Widespread yellow-level snowfall warnings have been issued by Environment and Climate Change Canada (ECCC) spanning along the Trans-Canada Highway west of the Rockies, across central and southern Alberta east to the Saskatchewan border, as well as south and west along the foothills. The national weather agency explained, “Snowfall amounts will vary widely, with general amounts of 10 to 25 centimetres by Thursday night. However, locally heavier amounts of 30 centimetres or more are possible.” On Wednesday morning, ECCC also issued yellow-level fog advisories southeast of Edmonton and special weather statements for most of central Saskatchewan. This event is expected to be so potent that warnings extend into Ontario. As of 7:30 a.m. Wednesday snow and mixed precipitation was already visible on some DriveBC cameras along Highway 1 and Highway 3, with blowing snow affecting visibility at times. Over the next 36 hours, Calgary may see intense amounts of snow falling over a brief period of time, or the city might end up on the low-end of these totals but, either way, conditions are expected to deteriorate rapidly once everything converges over the city. Despite warmer surface temperatures, road conditions will likely be briefly compromised as rain transitions to snow and gusty north winds combine to produce wet, sticky snow and isolated icy sections. Calgary will be cooler on Wednesday (compared to the normal high of 11 C) reaching a high of 6 C in the early afternoon. Rain is expected to start to fall mid-afternoon, and transition to snow by the late afternoon. By the evening heavy, wet snow is expected around the region, including within the city. A strong north wind of 20 to 40 km/h will precede and then coincide with that persistent precipitation, which will create near-zero visibility at times. The daytime high on Thursday in Calgary will be 14 degrees below average, but this will be short-lived. Temperatures will climb back to above-seasonal values by Saturday, which will lead to rapid melting.
