A combination of snow, fog, freezing drizzle, wind and sub-zero temperatures created the perfect storm early Monday, coating surfaces with a layer of ice while drivers also faced pockets of compromised visibility. Environment and Climate Change Canada (ECCC) issued a yellow-level freezing drizzle advisory for the Calgary area, noting “Roads, walkways and other surfaces will likely become icy and slippery. Icy surfaces will likely form and could be difficult to detect. Be very careful if walking or driving. If driving, turn on your lights, slow down and maintain a safe following distance.” Freezing drizzle is a type of precipitation that contains super-cooled water droplets that are smaller than that of freezing rain. Both will freeze on contact with surfaces like roadways, windshields, sidewalks, steps and parking lots, but freezing drizzle will fall in periods of light intensity and can create layers of ice that are difficult to detect – including sections of black ice that can make travel especially dangerous. These types of conditions will also enhance the risk of slips and falls in places like sidewalks, parking lots, and stairways. Around 7:30 a.m., visibility was near-zero in Calgary, and ECCC also issued a yellow-level fog advisory, explaining, “Travel will likely be hazardous in some locations. There may be a significant impact on rush hour traffic.” The fog is expected to mix out during the day Monday, and the ice is likely to melt throughout the morning. Some areas will likely ice up again overnight once temperatures drop down to 0 C or cooler, but that ice Tuesday should be more typical of a “freeze-thaw” cycle compared to the insidious nature of ice that forms during freezing drizzle events. A special weather statement was also issued by Environment Canada for areas west of Calgary – including Banff National Park – due to a system that is expected to travel along the foothills late Monday and early Tuesday. “Heavy flurries may affect travel overnight tonight and Tuesday morning. Bands of flurries are expected to pass through the region overnight tonight and Tuesday morning. Snowfall rates in these bands may be heavy, reducing visibility and causing snow to accumulate rapidly. Local snowfall amounts of 5 to 10 cm are expected as the flurries pass, particularly over higher terrain.” The national weather agency issued yellow-level snowfall warnings for northern Alberta and northeastern British Columbia, forecasting 15 to 20 centimetres of snow for that region. “Snowfall amounts will be variable but generally near 15 cm, except near the BC border where about 20 cm is expected.” Calgary will likely see some snow on Monday and Tuesday, however, it looks like most of the precipitation should stay west of the city. Daytime highs will remain slightly below seasonal in Calgary this week, before jumping back up to 15 C on Friday. The normal range this time of year is 9 C for a daily high and -4 C for the daily low.
