Updated: Apr 26, 2019
A series of upper-level disturbances will bring some precipitation chances for the Northern Plains and Canadian Prairies over the weekend. We were monitoring this, but a general "warmer" event was expected, therefore mainly rain. However, latest model trends are trending colder, bringing some snowfall into the forecast.
Above depicts the NAM 12-km resolution forecast for Sunday night, depicting a surface Low somewhere in northwest North Dakota. There are still disagreements between the European, Canadian and American models with the exact placement of the Low, but we chose to depict this position due to a "general" consensus for now. This Low placement would place the axis of heaviest precipitation somewhere in southern Saskatchewan, eastern Montana and western North Dakota.
How much snow? Well that is the tougher question to answer. It really depends on the precipitation type (IE temperature). A few degrees Celsius could mean the different between significant snowfall and little accumulations. Above is a model trend showing a lot of uncertainty regarding placement of snowfall. A general trend towards colder event is noticed however.
Assuming a colder trend:
Southern Saskatchewan: 15-25cm possible
Southeastern Saskatchewan: 20-30cm possible
Eastern Montana: >30cm possible
Extreme SW Manitoba: ~5-15cm possible
Manitoba should see rain from this event, being in the warm sector. We will update in the next few days as we get more information.
Discussion from NWS Glasgow, Montana:
While one system moves to the east Saturday morning, the next system moves in Saturday afternoon. A stacked surface and upper low moves through Eastern Montana Saturday Night and Sunday morning with a mix of rain and snow expected. Temperatures will likely be cold enough Saturday Night and Sunday for accumulating snow in some areas with the best chance north of the Missouri River. System will need to be watched in future model runs for heavy snow potential as models are trending colder. That system moves to the east Sunday Night ending the precipitation. Monday looks dry and cold with surface high pressure.