Hello there! Likely one of our biggest systems this winter is arriving tomorrow. On the forecast is blowing snow, very low visibilities, and most of all 10-25 cm of snow.
It will all start tonight, as a low enters southern Alberta. Usually snow will fall a good distance northward of a low, so even though the low is in southern Alberta, the snow is here. Even though we are getting very extreme amounts of snow (for December), this system is actually still a clipper. A confliction between warm air from the south and cold air from the north will create a strong stationary front, where a lot of snow will fall very quickly, and stay for about 12 hours. 12 hours is quite long for a clipper.
Total amounts of snowfall depend on where this boundary is placed. Canadian and European models have agreed extensively that the most snow will fall right over Edmonton, while US models have put it farther south. These models, however, have slowly been moving the snow northward over the last 24 hours, so most likely the Canadian and European ones are correct. I would say we have a 90% chance of >10 cm of snow falling, and about a 50% chance of >15 cm. Continuing, 20 cm of snow has about a 30% chance, and 25 cm about a 20% chance. It is only until we get to 30 cm that the chance falls below 10%.
When will this snow fall? Light snow will begin overnight tonight, then quickly turn heavy by sunrise. This heavy snow will continue all day, before diminishing tomorrow evening to a standstill at midnight. Relatively not that long, but for a clipper very lengthy.
There is also a risk of blowing snow tomorrow morning. Winds associated with this system will start overnight tonight coming from the northeast, then switch to more northerly and less intense around noon. Winds will be on average be around 20 km/h, with the strongest gusts possible above 40 km/h. This snow will definitely drift quite a lot. Temperatures will be between -10 and -20 for the duration of the snowfall, so wind chills are quite a concern.
So there you are. This snow will be quite impactful, so be aware of conditions tomorrow. Temperatures are going to go down and stay down for a while, so this snow isn’t going anywhere until spring.