We are currently tracking a strengthening Colorado Low as it approaches Northwestern Ontario throughout the day on Thursday with lasting impacts through to Sunday.
A large winter storm will push into Southern Manitoba beginning in the early afternoon on Thursday. Moderate to heavy showers will begin to spread into Northwestern Ontario with heavy snow pushing into Far Northern Ontario, near the Manitoba border.
Snowfall:
Areas in orange and marked with a '4' can expect snowfall totals between 30-50cm with locally higher amounts. This region includes Ney Lake and Stull Lake with the region bordering Sachigo Lake and Opasquia. Strong winds between 30-50km/h may create significant reductions in visibility with possible brief blizzard conditions.
Areas in the yellow and marked with a '3' can expect snowfall totals in the 15-30cm range with locally higher amounts towards 40cm. This region includes Swan Lake, Sachigo Lake, Sandy Lake, Deer Lake and is bordering Muskrat Dam and Severn Lake. Widespread blowing snow and hazardous traveling conditions can be expected in this region. A significant amount of freezing rain is also possible towards the eastern portion of this region.
Areas in the green and marked with a '2' can expect snowfall totals between 5-15cm of snow with locally higher amounts towards 20cm. This region includes Agusk Lake, portions of Big Trout Lake, Weagamow Lake, Pikangikum and is bordering MacDowell Lake. Most places should see between 5-10cm of snow with totals reaching 15cm in localized areas. If the cold air can push slightly further south, than rain may change over to snow resulting in totals nearing 15 or even 20cm in this region.
Areas in the blue and marked with a '1' can expect less than 5cm of snow with local pockets of 10cm. In Far Northern Ontario, this extends from Fort Severn and Hudson Bay south towards Big Trout Lake, Cat Lake and MacDowell Lake. In Northwestern Ontario, this area extends from Lake Superior to the Manitoba border with flurries. There will be limited to no accumulations in this area.
Rainfall:
Throughout the weekend, widespread rain will affect the province of Ontario. In Northwestern Ontario, rainfall totals between 40-60mm are likely, elsewhere, rainfall totals under 15mm are expected.
Areas in the yellow and marked with a '3' can expect rainfall totals in the 50-75mm range. This region includes Pikangikum and Woodland Caribou Park where significant freezing rain and ice pellets may lower these rainfall totals. At this time, the freezing rain is questionable, hence the addition of this region on the map. Another region is around Lake of the Woods, including Kenora, Sioux Narrows, Nestor Falls and Morson. Most places should see between 50-60mm of rain, although locally higher amounts are possible.
Areas in the green and marked with a '2' can expect rainfall totals between 25-50mm of rain with locally higher amounts towards 60mm. Across Northwestern Ontario, rainfall totals between 30-50mm are likely from Vermillion Bay through to Uchi Lake and Cat Lake, including places westward such as Red Lake, MacDowell Lake and Grassy Narrows. This stretch of rain also continues into Far Northern Ontario affecting places such as Big Trout Lake and Angling Lake. Rainfall totals may increase to 40-70mm if the cold doesn't push as far south. Rainfall warnings are in effect and may need to be expanded by Environment Canada. Around the shores of Lake Superiors, moderate to heavy showers with a possible isolated thunderstorm or two, will likely increase rainfall totals towards 15-30mm, locally higher. This includes Thunder Bay, Nipigon, Wawa, and Sault Ste. Marie.
Areas in the blue and marked with a '1' can expect less than 25mm of rain. This also includes places along the Manitoba border such as Sandy Lake, which, will see more snow than rainfall.
Freezing Rain and Ice Pellets:
As the precipitation begins to push across the region, in a line extending from Lake of the Woods towards the northeast towards Uchi Lake and Pipestone River Park, including everything to the west, freezing rain and ice pellets are possible. Into Far Northern Ontario, this region also extends to include Sandy Lake, Big Trout Lake, Agusk Lake, and Sachigo Lake. Current indications suggest freezing rain totals between 2-5mm, locally 5-15mm for the region
In a line from the Werner Lake-Red Lake area northward to include Pikangikum, Cat Lake and Pipestone River Park, significant freezing rain is possible. Current indications suggest freezing rain totals between 15-25mm may be possible in this area.
Much of the freezing rain may fall as ice pellets, although, if it doesn't, a large ice storm will be possible due to the strong gusty winds.
Hydro outages and hazardous driving conditions will be possible alongside damage in forests.