UPDATED DISCUSSION: Winter Storm Chances Increasing for Prairies and N Plains this Weekend

Saturday November 7, 2020

Threat level: HIGH

Impacts: HIGH (based on population density)

Confidence: MEDIUM (based on model agreements)

Expected hazards: Winter storm with all hazards: Snow, freezing rain, sleet and possible whiteout conditions

Expected Snowfall: 15-35+cm (Low Confidence in Location)

Expected Freezing Rain: 5-15+mm (Low Confidence in Location)

Time frame: Starting Saturday Afternoon (Nov 7th) into Early Monday Morning Nov 9th

Locations impacted: Southern Saskatchewan and Southern/Central Manitoba

Expected watch: winter storm watches

Most likely areas impacted: Southern Manitoba and Saskatchewan

Forecast map created by NZP Chasers on October 29, 2020

---

The following discussion was created by Lance Quackenbush. Join our site today and become a member of our community! Get emailed every time a blog post is posted.

Discussion: Model solutions agree that a shot of cold air is expected over Central Canada as a system over the northern Prairies ejects eastward later this week. A developing storm on the lee-side of the Rocky Mountains is expected to form into the weekend in the US, with development occurring near or over Colorado. This, combined with abundant moisture will setup a potent winter storm for the Northern Plain states of the US and the Southern Prairie provinces of Canada. Strong winds will be likely with this system, which could lead to the risk of blizzard conditions, though uncertainty still exists as to where the storm will track at this time.

Setup Leading to the formation of a Colorado Low on Friday

The newly formed low will track over the Plain states and eventually into Canada, though there is a fair amount of uncertainty as to how far west or east the low track will be. There will however be abundant moisture associated with the low wherever it tracks, meaning heavy snow will occur where it remains colder. All types of winter precipitation will be possible in the transition zones, with significant amounts freezing rain possible for some regions in Manitoba or Saskatchewan.

Model Positions of the Colorado Low Saturday morning showing Track Uncertainty

The European Model is currently the farthest west with the Colorado low, bringing it over Southeastern Saskatchewan where it will occlude, which would bring a period of freezing rain to Western Manitoba, heavy snow to Saskatchewan, and rain to the Winnipeg region.

On the other hand, the Canadian and American Global Models bring the low over SW Manitoba and Central Manitoba respectively, which would bring the chances of freezing rain farther east. If the Canadian model solution occurs, rain will fall in Winnipeg with freezing rain over southwestern Manitoba and a transition to sleet and heavy snow to the north and west of Brandon. Behind the low, snow will affect all of southern Manitoba and Saskatchewan, and strong winds will be possible as the low exits, creating the risk for white out conditions in snow.

In the American GFS model solution, which is the farthest east, Freezing rain could be a big concern for Winnipeg where 6-12 hours of ice could fall. Snow will would be lighter in Saskatchewan, with the heaviest snow in Southwestern Manitoba through the Brandon area where 30+cm could easily occur.

Snowfall varies via model, but 30cm+ could occur in the Heaviest Snows with the Low

Conclusions

A significant winter storm is looking more likely for the Prairies and Northern Plains into this weekend. However, a fair amount of model spread remains, which is making it difficult to pinpoint who will see what precipitation type and how much of each precipitation type. Monitor updated forecasts over the next several days as this event draws nearer and models come into better agreement about possible impacts.