A strengthening Colorado Low will bring a long-duration, widespread winter storm to portions of the Upper Midwest in the United States before moving into Manitoba and Northwestern Ontario with blizzard and ice storm conditions.
A band of light to moderate snow will cross Southern and Central Manitoba along a cold front throughout the early morning on Thursday bringing a widespread 2-5cm, locally 10cm of snow. Into the late morning and early afternoon, conditions will begin to deteriorate as a Colorado Low begins to push north towards the region.
Widespread snow is expected across Southern and Central Manitoba extending from the Saskatchewan border into Far Northwestern Ontario. Across the Southeastern Manitoba into Northwestern Ontario, heavy rain will begin to soak the already saturated ground. This will also begin the long-duration ice event which is expected along the Ontario-Manitoba border, east of Winnipeg, extending northeast towards Red Lake and Weagamow Lake in Northwestern Ontario.
The exact location of the system is yet to be determined. Most global forecast models are consistent with the system moving over the Lake of the Woods area, although, a slight shift in the track will make a major change in the forecast in terms of snowfall/rainfall locations, more significantly, the location of the significant ice.
SNOWFALL & BLIZZARD CONDITIONS – SOUTHERN REGIONS
Accumulations from the winter storm will vary greatly throughout Southern Manitoba with the heaviest accumulations throughout the higher terrain. Current guidance suggests snowfall totals will be highest between 30 and 50cm, locally higher towards 65cm+, in the extreme southern portion of Manitoba throughout the Red River Valley into the Darlingford Moraine region. This area has been highlighted with the extent of dark pink in the forecast map. Isolated totals near 70cm may be possible. Snowfall warnings are in effect for portions of this region.
Throughout this region, widespread winds between 60-80km/h are likely to cause significant blowing snow and possibly blizzard conditions. Whether blizzard warnings are issued or not, significant impacts on travel are likely across much of the major highways in the southern portion of the province. Highways such as 1 (Trans Canada Hwy.), 2, 3, 5, 23 and 75 should be avoided throughout the weekend.
The criteria for a blizzard classification and blizzard warning in Canada follow the 4-4-4 rule: 40km/h winds or greater causing widespread reductions in the visibility to 400 meters or less for at least 4 hours. A full list of alert criteria can be found here.
Extending inland towards Lake Manitoba, including Portage la Prairie, snowfall totals will be less in the 20-40cm range although local totals between 40-60cm are possible. The extent of this region can be seen in pink. This region also includes Boissevain to the west and Winkler/Altona to the east. This region continues in a swath between Lake Manitoba and Lake Winnipeg, extending just east of the lake as well, including Bloodvein. This region is less likely to see the locally higher totals. Snowfall ratios in this region will likely peak around 10:1 (10 inches of snow for 1 inch of water).
Extending out in all direction, snowfall totals are likely to decrease. This is seen in the dark blue shade on the map. Towards the west of Lake Manitoba, snowfall totals between 10-20cm are likely. There was some discussion within the team as to whether or not we should extend this region to the west of Northern Lake Winnipeg, although, we have went against this due to the expected location and size of the system. This remains a possible option, but, less likely at this time. Between Southern Lake Winnipegosis and Lake Winnipeg, 10-20cm of snow is also possible. Towards the east, including Winnipeg, as well as areas east of Lake Winnipeg to the Ontario border, snowfall totals between 10-20cm are likely throughout the weekend with local totals towards 30cm. Finally, areas northeast of Lake Winnipeg through the Poplar region towards the God’s Lake region will also see between 10-20cm of snow with an increased risk of 20-30cm.
Towards the west into Saskatchewan, a brief period of snow is likely to bring generally 5cm of snow to the region. Further into Manitoba, 5-10cm is expected from the ‘after side’ of this system. In Ontario and Southeastern Manitoba, 5-10cm is likely with most, if not all, the snow remaining melt-on-contact due to the expected heavy rainfall throughout the system. Towards Lake Superior, snowfall totals will be localized to 5cm with limited to no visible accumulations likely.
SNOWFALL & BLIZZARD CONDITIONS – NORTHERN REGIONS
Accumulations from the winter storm will be significant along the Manitoba/Ontario border. The heaviest accumulations will occur in the pink region. This region extends from between Poplar Park Reserve in Manitoba and Opasquia Park in Ontario along the border to Sturgeon Lake in Ontario. Snowfall totals between 25-45cm are likely with local amounts approaching or surpassing 50cm. Outside of this region, a widespread 10-20cm, locally 25cm is likely within the dark blue region. This extends from Lake Winnipeg through to Sandy Lake and Sachigo Lake in Ontario towards Hudson Bay. with the heaviest accumulations throughout the higher terrain. A winter storm warning is in effect for portions of this region.
In the light blue region, which extends from Hudson Bay through to Lake Winnipeg and Big Trout Lake, Ontario, snowfall totals between 5-10cm are possible. Local totals towards 15cm are possible into Manitoba, although, current guidance suggests this is unlikely.
Across Southeastern Manitoba, southeast of Winnipeg, extending into Northwestern Ontario along the Manitoba/Ontario border, a long-duration ice storm is increasingly likely.
As temperatures near 0 C throughout the long-duration of the winter storm, freezing rain and ice pellets will be a large concern along the border of the provinces towards the south. With the system expected to track of Lake of the Woods, heavy rain is likely across portions of Southeastern Manitoba (Buffalo Point westward) and much of Northwestern Ontario. A thin band of moderate to heavy freezing rain is likely to remain stationary for multiple hours.
Extending from the Vita/Marchand area in Manitoba through the Ontario border into the Red Lake and MacDowell Lake areas, heavy freezing rain between 15-30mm of ice is possible. In a tight gradient outside of this region, the freezing rain totals will quickly drop off in a thin 5-15mm ice range followed by a large 2-5mm ice range. This larger area extends from Hudson Bay through Big Trout Lake into the Whiteshell Provincial Park area in Manitoba. The attached map highlights the possibly affected areas, but due to the tight gradient, we have not added totals onto the map.
Widespread wind gusts between 40-60km/h, locally higher towards Southern Manitoba will likely result in widespread power outages in the affected communities. Highways such as 1 /17 (Trans Canada Hwy.), 44, 105, 307, 596, 658 should be avoided throughout the weekend.
Across Northwestern Ontario and Southeastern Manitoba, heavy rain will bring a wide swath of 40-70mm to the region. Local totals between 70-90mm will be possible in the strongest bands in the system. Rainfall warnings have been issued for these regions as there are numerous communities already dealing with flooding throughout the area.
You can continue to monitor weather alerts issued by Environment Canada from their website: https://weather.gc.ca/warnings/index_e.html