They say waiting is the hardest part, and as the province collectively holds its breath ahead of the arrival of what's being described as potentially the worst blizzard in decades, the waiting will end late tonight and overnight into Wednesday. Environment Canada has issued a Blizzard Warning for most of Southern Manitoba, with areas east of the Red River under a Winter Storm Warning.
Blizzard Warnings are issued when winds of 40 km/hr, or greater, are expected to cause widespread reductions in visibility to 400 metres or less, due to blowing snow, or blowing snow in combination with falling snow, for at least 4 hours. Winter Storm Warnings are issued when conditions are favourable for the development of severe and potentially dangerous winter weather, including blizzard conditions, major snowfall (25cm or more within a 24 hour period) and a significant snowfall combined with other winter weather hazard types.
"We have one final day to prepare before conditions deteriorate, travel becomes extremely challenging, if not out of the question, and we're in the thick of things for 48 hours or more," said CMOS Accredited Weathercaster Chris Sumner Tuesday morning. "I was really pleased to witness personally, and hear second-hand, how many were heeding the early warnings about this system, and were stocking up Monday on groceries, fuel and other necessities. If you still have a few things on your list, do your best to get those checked off by early evening Tuesday."
According to Environment Canada, the Colorado low responsible for what's to come will move toward Minnesota Tuesday night bringing a heavy swath of snow from southeastern Saskatchewan through most of southern Manitoba. The snow will start early Tuesday evening near the International border, then push northward throughout the night. By Wednesday morning heavy snow will be falling in much of the area as the storm continues to push northward. Strong northerly winds will develop, and persist into Friday morning as the low slowly pivots through Minnesota on its way into northwestern Ontario. This will lead to widespread blizzard conditions developing tonight into early Wednesday morning.
Widespread snowfall accumulations of 30 to 50 cm are expected, with possible accumulations as high as 80 cm possible along terrain features such as the western escarpment of the Red River Valley, the Riding Mountains and the Turtle Mountains due to topographically enhanced snowfall.
"This low is being fed by moisture rich air from the Gulf of Mexico, and that's what's leading to the potential for such substantial snowfall totals," explained Sumner. "Because we're expecting a generally northeasterly wind pattern for the first day or so of the storm, we'll more than likely see some topographically enhanced snowfall over those higher terrain areas. As air rises, it cools, and cooler air has less capacity to hold water vapour than warmer air. What that means is, as those parcels of air move higher in elevation along places like the Manitoba escarpment and Riding Mountains, the water vapour will be forced to condense, and because temperatures will be below zero, the precipitation will fall as snow at a relatively higher rater than lower lying areas."
Sumner noted there will continue to be tweaks to expected snowfall totals throughout the storm event, because even slight changes in the Colorado low's track will impact which areas see the most snow.
"Yes, we're saying 30 to 50cms is the generally expected total, but there could be variation over a general area," he said. "Now, that's not to say areas within the Warnings will completely miss out on the snow, but what it does mean is the final numbers may be within the range of that forecast, or potentially higher or lower, somewhat."
One of the tweaks is coming into play in the latest forecast model runs is the timeline for the strongest winds, and which areas will see the most powerful wind gusts. Currently, the Red River Valley and the Southwestern corner of the province are expected to see the strongest winds, and there is a possibility some areas of the Red River Valley may see a brief reduction in wind gusts Wednesday afternoon, before they pick up again Thursday.
Environment Canada continues to stress not planning on travelling, with this storm continuing to show potential to be the worst blizzard in decades.
"I can't stress enough how difficult travel may be Wednesday, Thursday and into Good Friday morning," said Sumner. "Highway closures are likely, and considering what conditions may be like, it could be extremely difficult for first responders to reach you if you end up stuck, especially in a rural area. Please avoid unnecessary travel, and again, use Tuesday to make those final stops and preparations."
Conditions should begin to improve on Friday as the winds taper off and the heaviest snow moves into northern Ontario, but it's likely travel will still be challenging.
"My take away message today is please take this storm seriously, keeping in mind what the impacts were like during the Thanksgiving 2019 event, the 'Storm of the Century' in April 1997 and the November 1986 blizzard which buried parts of the province under more than a foot of snow," said Sumner.