I wonder what the topic should be for this week’s article? Maybe, just maybe, we should take a look at the massive blizzard that struck and paralyzed over three-quarters of Manitoba last week. What looked initially in the weather models to be a modest storm turned out to be a record-breaking storm that impacted all of northern and western Manitoba. The only part of Manitoba that didn’t really feel much of an impact from this storm system was the southeast.
- Read more: Western Manitoba opens doors for stranded travellers
- Read more: Western Manitoba prepares as province releases its first flood outlook
I wouldn’t say this was a strange storm; after all, our biggest storms occur in March and April, because all of the major ingredients are in place. For a big storm to develop you need plenty of moisture, which we see in the fall and spring, but rarely in the winter. You also need plenty of cold air, which is often lacking in the fall, but is around in the winter and early spring. What was a little unusual about this storm was the track it took. I would love to be able to analyze the path of major storm systems over the last 50 or so years to see if there has been a change. Unfortunately, I don’t have access to that kind of data. Based on my memory only, it seems to me as if we have seen a shift in the path of big storm systems.
Growing up, I remember the big winter storms would develop to our southwest, often over Colorado (thus the name “Colorado low”), then track northward toward the Dakotas before tracking off to the northeast. These systems would bring stormy conditions to southern and central regions, with southeastern regions often the hardest hit. Over the last several years some of our biggest storms have developed in the same general region and tracked northward, but their shift to a northeastern track doesn’t take place until they have made it well into Manitoba. This was the case with this storm system. The result is that western and northern regions saw the heaviest snowfall, with southeastern regions missing out on most of the heaviest precipitation.
This historic storm began as an area of low pressure over Montana. As the low started to push northward a second area of low pressure developed over Colorado, and as it pushed northward, it merged with the Montana low over western Manitoba. This allowed the low to deepen fairly rapidly, helping to pull up plenty of moisture and provide very strong winds.
This alone wouldn’t have created the storm system we ended up with. The final ingredient, which has often been missing this winter, was a very strong area of arctic high pressure that was building south on the back side of this system. Put that deep area of low pressure beside a strong area of high pressure and you end up with a truly impressive pressure gradient, which is just a fancy way of saying “really strong winds.”
What was also impressive with this system was the size that it achieved. By late Tuesday and into Wednesday the circulation around this storm stretched from southern Manitoba all the way to almost Baffin Island. At one point, wind speeds were gusting above 70 km/h at pretty much all locations in Manitoba — truly an amazing amount of air moving across our province.
I don’t have the space to go into all of the details on this storm. Regions saw thundershowers and thunder snow. Temperatures plunged from well above freezing to well below freezing within 10 to 20 minutes as the cold front pushed through, changing rain into blinding snow within minutes. Snow and high winds lasted for days instead of hours.
The tables shown below give you a compilation of the different storm summaries put out by Environment Canada. Hopefully in my next article we’ll get to that spring flood forecast and take a look at how this storm may have affected that.