Notice: Forecast models are still in a disagreement over the track, Snow line, and intensity of this Low pressure system. If you live near the expected snow-rain line(Saskatoon, Edmonton, Red Deer, And Calgary) be prepared for no snow at all or 30+cm of snow. It all depends on the track and timing. Thundersnow/thunderstorms may cause higher localized accumulations.
A major spring storm in expected to begin tonight and track through Alberta, Saskatchewan, and Manitoba. There is still some disagreement in the models as for the exact track, and temperatures however it appears the snow-rain line should be the Yellowhead highway, and along the QE2 highway. To the south and east we can expect rain or a mix of rain and snow with little accumulation of snow.
Upwards of 25mm of rain can be expected near the snow line and to the southeast, as well as showers and even thunderstorms.
To the north snowfall amounts well over 30cm can be expected and thundersnow is a widespread general risk.
The maps below are my interpretation of the forecast models. NAM, GFS, GEM global, and GEM Regional over multiple runs.
Starting off mostly as snow Thursday morning over most areas, switching to rain or mix near and southeast of the snow/rain line around 9am to noon. The snow line will move south overnight Friday, bringing accumulating snow in cities such as Edmonton, Red Deer, Calgary, and Saskatoon. During the day Friday the snow line may not move north again and snow slowly tapers off in Alberta into early Saturday.
Aftermath: Most areas that get heavy snow likely retain that snowpack well into the work week or the following weekend. Record breaking cold is possible Sunday morning as temperatures could dip as low as -15C in Central and Northern Alberta behind the low. Well below normal temperatures could last the rest of next week as well.
The risk of flooding is high, especially on the SK side of the storm as the 40-50cm of snow melts into already swollen creeks and rivers.
Wind gusts of 50-80km/h will cause blowing snow and reduced visibility in areas that receive heavy snowfall.