A record-breaking Colorado Low over the Upper Midwest Plains in the United States has caused record-breaking pressure recordings in the area, hurricane-force wind gusts and widespread road closures is slowly weakening and moving into Ontario. The system will bring heavy snow to portions of Northern and Far Northern Ontario as well as heavy rain to portions of North Central Ontario. Freezing rain for portions of Northeastern Ontario and even the risk of severe thunderstorms in Southwestern Ontario.
Light to moderate snow is expected to move into Northwestern Ontario on Wednesday evening between 6 and 8pm near Morson. The snow will push northeast into Northern Ontario with the snow reaching areas Kenora, Vermillion Bay, Sioux Lookout and Ear Falls by midnight on Wednesday. By the morning hours on Thursday between 6 and 8am, the snow will continue eastward towards Armstrong, Fort Hope, and Pickle Lake. The snow will continue west, northwest, and north of Lake Superior before strengthening north of Lake Superior from Armstrong and Wabakimi Park northeast towards Attawapiskat. In the middle of the afternoon between 2 and 4pm, the rain is likely to make a change over to moderate or heavy snow for areas northwest and north of Lake Superior, over the Armstrong, Gull Bay, English River, and Nakina areas. The snow will continue northeast into Friday with the snow ending from west to east. The snow will end in Far Northern Ontario before scattered, light to moderate snow develops across Northeastern Ontario.
Blue or '1':
Areas in the blue or marked with a '1' can expect less than 5cm of snow. This includes areas around Lake Superior such as Thunder Bay, Nipigon, and Wawa with limited snow near Atikokan and Upsala as well. Areas towards the northeast near Moosonee, Smoky Falls, Hearst and White River will also see then 1-3cm of snow. Areas in the south near Sault Ste. Marie, Sudbury, Manitoulin Island, North Bay, and Temiskaming Shores may not see any or less than 2cm of snow over the forecast period. Areas between Smoky Falls through Hearst into the Timmins and Chapleau area may see between 4 and 6cm of snow. In the Far North, areas around Fort Severn, Ney Lake, Sandy Lake, Muskrat Dam, and Big Trout Lake will likely see between 1 and 3cm of snow with locally higher amounts towards 2 and 4cm around Big Trout Lake and Deer Lake. Towards the east near Peawanuck and Angling Lake, local amounts between 4 and 8cm are possible, although, based on current forecasts, this is unlikely to meet the 5 to 10cm range (green).
Green or '2':
Areas in the green or marked with a '2' can expect between 5 and 10cm of snow. This includes much of Far Northwestern Ontario including Moshikopaw Lake, Kingfisher Lake, Weagamow Lake, Pikangikum and Cat Lake. Towards the south, this also includes Red Lake and Uchi Lake as well as Fort Frances, Ignace and English River, including Fort Albany. Based on the amount of rain and the time of the switchover from rain to snow, areas between Fort Frances and English River may see slightly fewer amounts in the blue range.
Yellow or '3':
Areas in the yellow or marked with a '3' can expect between 10 and 20cm of snow. This includes Kenora, Ears Falls, Vermillion Bay, Dryden and Morson where 10 to 15cm is likely and local amounts towards 20cm. Areas between Sioux Lookout and Savant Lake are likely to see between 12 and 16cm of snow with local amounts towards 20 and 24cm of snow. A patch to the west of Lake Nipigon over Gull Bay could see local amounts towards 15 to 20cm of snow. This is questionable based on the timing and location compared to the system although, with lots of model agreement, we have gone on the high side and included this in the 10 to 20cm range instead of the green range. Areas towards the north over Pickle Lake and Summer Beaver can expect between 14 and 18cm of snow, locally 20 to 25cm. Areas including Polar Bear Park and Webequie can expect between 15 and 20cm of snow with local amounts towards 25 or even 30cm of snow. There is some questioning model data on the exact location of the heavy snow swath, therefore, we have gone low but added an 'Area of Interest' over the area.
Orange or '4':
Areas in the orange or marked with a '4' can expect between 15 and 30cm of snow. This includes a large area from Hudson Bay and James Bay near Attawapiskat extending inland towards Missisa Lake, Landsdowne House, Ogoki, Fort Hope, Wabakimi Park, and Armstrong. Snowfall totals between 20 and 30cm are likely although isolated pockets towards 15cm are possible. We have added an 'Area of Interest' over this region as there is the potential to see between 25 and 45cm of snow in this area. The risk is low, but not zero for snowfall amounts that extreme, therefore, we went with the lower scale but the 'Area of Interest.'
Rainfall and Flooding
Moderate rain is expected to move into Northwestern Ontario on Wednesday evening between 6 and 8pm near Fort Frances and Thunder Bay. The rain will push northeast into Northern Ontario with the rain reaching areas near or slightly northeast of Lake Nipigon as well as areas near Manitouwadge and Carmat by midnight on Wednesday. By the morning hours on Thursday between 6 and 8am, the rain will continue eastward towards Moosonee and Fort Albany with lingering impacts over Marathon, Wawa, and Hearst. The rain is likely to have let up from Nipigon northwest and west. Near noon on Thursday, a weak front is expected to cross Southwestern Ontario bringing a line of non-severe thunderstorms and showers to the region. In Northern Ontario, the rain will continue east and northeast of Lake Superior before redeveloping for a final time north, northwest and west of Lake Superior. In the middle of the afternoon between 2 and 4pm, the rain is likely to make a change over to moderate or heavy snow for areas northwest and north of Lake Superior, over the Armstrong, Gull Bay, English River, and Nakina areas. Into the early and mid-evening, there is the risk of a line of showers, including the risk of non-severe and isolated severe thunderstorms across Southwestern Ontario. Moderate to heavy downpours are possible inside this line of light to moderate rain. By the overnight period, the temperature will begin to drop across the province and lingering showers will start to end across Southern and Northeastern Ontario before some light snow showers spread across the region.
Blue or '1':
Areas in the blue or marked with a '1' can expect less than 10mm of rain. In Northern Ontario, this includes Kenora, Dryden, Ignace, Armstrong, and Ogoki. These areas will likely see mainly snow although some pre-snow rain is possible. Accumulations between 2 and 4mm are likely at most for these areas with the exception near Sioux Narrows and Morson where amounts between 4 to 8, locally 10mm may be possible.
Green or '2':
Areas in the green or marked with a '2' can expect between 10 and 20mm of rain with local totals near 30mm. In Northern Ontario, this includes Fort Frances, Mine Centre, Gull Bay and English River where 8 to 16mm is likely. This area also includes Fort Albany, Moosonee, Kesagami Park, and Fraserdale. Further southeast to include Mammamattawa, Hearst, Timmins, Chapleau, and Agawa Bay, rainfall totals between 10 and 20mm is likely. Locally higher amounts towards 30mm are possible, mainly near Hearst, Agawa Bay, and Mammamattawa. Towards the southeast over Sault Ste. Marie, Temiskaming Shores, Temagami, Sudbury, and Manitoulin Island, rainfall totals between 12 and 18mm are likely with local amounts towards 25mm. Local pockets across the area may see totals between 4 and 12mm of rain depending on where the moderate rain bands set up within the system, the biggest risk of this appears between Fraserdale, Cochrane, Sudbury, and Nicholson. In Southern Ontario, areas west and north of a line which runs from Arnprior through Plevna, Peterborough, Vaughan, Mississauga, and Port Dover can expect between 10 and 20mm of rain with local amounts towards 25mm. Areas south and east of this line including Niagara, Toronto, Kingston, Perth, Cornwall, and Ottawa can expect amounts less than 10mm. Areas east of Lake Huron extending south to Lake Erie including Sarnia, Windsor, and Chatham as well as Wingham, Stratford, Woodstock, and Delhi may see locally higher amounts between 25 and 50mm of rain due to enhanced thunderstorms which may cross over the region with a downpour or multiple may cross over the same area all with downpours. This range may extend into Grey/Dufferin/Simcoe/Muskoka regions depending on the lining of the thunderstorms and track of multiple thunderstorms. A patch from Ottawa to Hawkesbury also has our interest for locally higher amounts between 10 and 20mm, although, due to some model disagreement, we have left this out of our map. If an area sees thunderstorms, locally higher amounts than what is forecasted are possible.
Yellow or '3':
Areas in the yellow or marked with a '3' can expect between 10 and 30mm of rain with local amounts towards 40mm. Areas around and including Nakina, Pagwa, Ameson, Longlac, and Hornepayne are likely to see between 10 and 20mm of rain. We have included this in the yellow instead of the green as there is more model agreement that 30mm in local areas is possible. Further south towards Beardmore, Raith and Lake Superior Park, rainfall totals between 15 and 25mm are likely. Locally higher amounts between 25 and 35mm are possible. Areas around and including Thunder Bay, Nipigon, Marathon, Pukaskwa Park, and Wawa are likely to see between 20 and 30mm of rain with local amounts towards 40mm. Isolated pockets of 2" (50mm) is possible in this area although the risk is low.
The Ministry of Natural Resources and Forestry has issued a widespread FLOOD WATCH for all of Southern Ontario as well as portions of Northern Ontario including Sault Ste. Marie, Sudbury, North Bay, Manitoulin Island, Temiskaming Shores, Fort Frances, Thunder Bay, Armstrong, Fort Hope, and Webequie. We encourage you to check your local conservation authorities as multiple local statements, watches, and warnings have been issued. The Ministry of Natural Resources and Forestry can be found here. #TurnAroundDontDrown
Freezing rain/drizzle is expected to develop over portions of Northeastern Ontario along the Quebec border extending from Kesagami Lake to Cochrane/Timmins to Sultan/Ruel before connecting back at the Quebec border. A trace to 2mm is likely of accretion with local totals between 2 and 4mm. Besides this, a trace to no accretion can be expected from this listed area to Lake Superior and Lake Huron.
Because of the limited risk, we have not included a map for this risk.
Severe thunderstorms are possible with this system is the Extreme South part of the province. The full forecast can be found here: https://www.weatherwatch.space/post/low-severe-thunderstorm-risk-across-extreme-southwestern-ontario-march-14th-2019