We are closely tracking a Texas Low which is currently (as of Saturday evening) sitting over portions of the United States, near the Gulf of Mexico. This system is and will be producing a severe weather outbreak with a possible tornado outbreak on Saturday extending from Texas to Mississippi and on Sunday from Ohio and New York extending south into Florida and the Gulf of Mexico, including everything in between. Multiple tornadoes have been reported, including multiple fatalities. Our thoughts are to those affected by this system and these tornadoes. In Ontario, this system will bring a swath of 10 to 15, locally 20 or even 25cm of snow in Southern and Central Ontario including a threat of freezing rain and heavy rain, possibly producing flooding.
As the system pushes north into Southern Ontario, light to moderate showers will spread into the Extreme South and Southwestern Ontario into the morning hours on Sunday. By noon, light to moderate showers will continue extending across Southwestern Ontario into the GTA. At times the showers could be scattered and spotty. Towards the north, moderate to, at times heavy, snow will affect portions of the Bruce Peninsula and the shores of Georgian Bay (Midland, Parry Sound, etc). Freezing rain mixed with ice pellets will cover much of the higher elevations around the Dundalk Highlands extending northwest into the Owen Sound/Wiarton region. By the mid-afternoon (2 to 4pm), scattered showers will continue across portions of the GTA, Golden Horseshoe, Extreme South, Southwestern Ontario and the southern portion of Central Ontario. There is the risk of some localized thunderstorms across the Extreme South and Southwestern Ontario during this time frame. The light freezing rain will continue near the highest elevations of the Dundalk Highlands. A patch of freezing rain mixed with ice pellets may develop over portions of Central and Eastern Ontario between Madoc and Dorset. Moderate to heavy snow will continue for portions of Central and Eastern Ontario including Manitoulin Island, the North Bay/West Nipissing Area and the Bruce Peninsula. Into the early evening, scattered showers and thunderstorms will affect portions of Central and Eastern Ontario, including the GTA and Golden Horseshoe region. A large severe weather outbreak is expected along the southern shores of Lake Erie in Ohio/Pennsylvania/New York. We are not expecting severe thunderstorms in Southern Ontario, although, we can't rule out the severe front clipping portions of the Niagara region. We will be watching despite the low risk. A large area of freezing rain/ice pellets/snow is likely over the Algonquin area extending into Renfrew County. Snow will push north into Northern Ontario affecting Manitoulin Island, Sudbury, and Temagami. By the late evening, scattered light showers with embedded thunderstorms will remain possible over portions of Southwestern Ontario with the main part of the 'action' centered around Eastern Ontario. Moderate to heavy showers with thunderstorms are possible across the region. The expected severe front may track over Lake Ontario and may clip portions of Prince Edward County. Due to the cold waters in Lake Ontario, we are expecting the severe threat to diminish before affecting land. Despite this, heavy rain is possible and likely. Light freezing drizzle may affect the Dundalk Highlands once again. During the overnight hours between Sunday and Monday, a final burst of showers with thunderstorms will affect Southwestern Ontario with another round of moderate snow across the Bruce Peninsula and Algonquin regions. Freezing rain will affect the Dundalk Highlands. The showers will change over to snow as the temperature dips below the freezing mark. As the showers continue east into the morning hours, moderate to heavy snow will continue across Grey/Bruce Counties extending into the Midland/Parry Sound/Algonquin regions. Light snow will fill in across the Extreme South and Southwestern Ontario. The moderate snow alongside the already fallen snow and wind gusts may cause local bus cancellations across the Parry Sound/Muskoka/Grey/Bruce region. It's too early to say although, either way, our daily snow day forecast will be updated. Our snow day forecast can be found here. By the mid-morning on Monday, the system will be ending with lingering light showers in the southern portions of Eastern Ontario with light to moderate snow across Central and Eastern Ontario. By the late evening, the Ottawa/Perth regions can expect some lingering flurries before the system fully pulls away from the province and affects Atlantic Canada.
Snowfall (and Ice Pellets)
Blue or '1':
Areas in the blue or marked with a '1' can expect less than 5cm of snow. This area includes all the Extreme South, GTA, and Golden Horseshoe regions. This also includes portions of Central and Eastern Ontario such as Ottawa, Kingston, Belleville, and Peterborough. Areas in Northeastern Ontario such as Sudbury, Espanola and Temagami can also expect near 5cm of snow. Most places in this region should see between 1 and 3cm of snow although areas like Goderich, Arthur, Lindsay, Peterborough, Perth, Ottawa, and Northeastern Ontario can expect totals in the range from 2 to 4cm of snow with local amounts between 4 and 6cm.
Green or '2':
Areas in the green or marked with a '2' can expect between 5 and 15cm of snow. This includes a large swath of Southern Ontario. Areas between and including Wingham, Kincardine, Hanover, Orangeville, Shelburne, Collingwood, Orillia, Minden, Woodview, Bon Echo Park, and Arnprior. This area can expect a widespread 5 to 10cm of snow with local amounts as high as 15cm. Areas between and including Owen Sound, Saugeen Shores, Meaford, Midland, Haliburton, Bancroft, and Renfrew can expect snowfall totals between 8 and 12cm of snow with local amounts near 15cm. In Northeastern Ontario, Manitoulin Island, Killarney, French River, and North Bay can expect between 5 and 10cm with local amounts towards 15cm. Slightly further south towards Tobermory, Britt and Powassan, snowfall totals between 8 to 12cm are likely with local amounts near 15cm.
Yellow or '3':
Areas in the yellow or marked with a '3' can expect between 10 and 20cm of snow. This includes a large swath of Southern Ontario. This includes most of the Bruce Peninsula such as Lion's Head and Wiarton. This area also includes all of Algonquin Park and much of the Renfrew/Haliburton/Muskoka regions. Areas between and including Parry Sound, Dorset, Barry's Bay, Cobden, Bayfield Inlet, South River, and Sonecliffe are included in this region. Most places should see between 10 and 15cm of snow although amounts as high as 20cm are possible. In the 'Area of Interest' which extends from Parry Sound into Algonquin Park and the Pembroke, Barry's Bay, South River regions, snowfall totals as high as 25cm are possible. We have not included this in the next level on the map due to the low confidence.
If the system pushes further north than what we have forecasted, everything on the map can be pushed north by 1 to 2 listed places on the map. We are confident with our forecast, although, there are some conflicting models which show otherwise.
Freezing Rain
Blue or '1':
Areas in the blue or marked with a '1' can expect less than 2mm of ice accretion. This includes a portion of Central, Eastern, and Southwestern Ontario. Areas such as Saugeen Shores, Wiarton, Angus, Beaverton, Barrie and Fenelon Falls will likely see trace amounts while areas such as Owen Sound, Minden, Haliburton, and Hanover are likely to see amounts from a trace to 2mm. We are expecting more ice pellets than freezing rain for areas across portions of Central and Eastern Ontario such as Orillia, Dorset and Barry's Bay, therefore, we haven't included them within this region. If more freezing rain than ice pellets fall, than these areas may see between a trace and 2mm.
Green or '2':
Areas in the green or marked with a '2' can expect between 2 and 5mm of ice accretion. This includes portions of Central and Eastern Ontario including Bancroft, Bon Echo Park, Woodview, and Plevna. Most places will see between 2 and 4mm although local amounts within this region may be as high as 4 to 8mm. We have not included this on the map as we are less confident in this occurring, although, as there is a risk, we have included this in an 'Area of Interest'. In Southwestern Ontario, a widespread 2 to 4mm is likely for areas near Owen Sound, Meaford, Mount Forest, and Arthur.
Yellow or '3':
Areas in the yellow or marked with a '3' can expect between 5 and 10mm of ice accretion. This includes a portion of the Dundalk Highlands such as Markdale, Shelburne, and Orangeville. Most places should see between 4 and 8mm although local totals upwards of 10mm are possible. As the freezing rain may fall at a moderate or heavy intensity, all the fallen freezing rain may not stick, therefore, totals may appear lower than shown on the map. As local amounts may reach just over 10mm, we have included this in an 'Area of Interest'.
Rainfall and Flooding
Blue or '1':
Areas in the blue or marked with a '1' can expect less than 15mm of rain. This includes a large area north of Amberley, Hanover, Markdale, Washago, Minden, Bancroft, and Cobden. This is due to the snowfall and freezing rain which may take higher priority. Areas in Grey County such as Hanover may see near or locally over 15mm. This is due to thunderstorms which may develop and enhance rainfall totals.
Green or '2':
Areas in the green or marked with a '2' can expect between 15 and 25mm of rain. This includes a swath of Southern Ontario extending along the shores of Lake Huron including Tiverton, Kincardine, Goderich and Brand Bend extending inland to including Mount Forest and Listowel. Areas further east such as Shelburne and Orangeville may also see between 15 and 25mm of rain. Areas higher in the elevation may see near or slightly below 15mm due to freezing rain taking higher priority. Further east over Barrie, Newmarket, Fenelon Falls, and Apsley, rainfall totals between 15 and 25mm are possible. Finally, areas further east such as Bon Echo Park and Renfrew may see between 15 and 25mm of rain with local amounts as high as 30 or 35mm. Rainfall totals over 25mm are possible if an area receives thunderstorms.
Yellow or '3':
Areas in the yellow or marked with a '3' can expect between 20 and 40mm of rain. This includes another large swath of Southern Ontario such as Windsor, Sarnia, London, Kitchener, Hamilton, and Toronto. Most of these places will see between 20 and 30mm of rain with local amounts closer to 40mm of rain. Any thunderstorms which pass through this region may create totals over 40mm. Further east including Peterborough, Macdoc, Sharbot Lake, Perth, Ottawa and Arnprior, rainfall totals between 25 and 35mm are likely with amounts as high as 40mm possible. Local totals towards 50mm can't be ruled out, especially with thunderstorms.
Orange or '4':
Areas in the orange or marked with a '4' can expect between 30 and 60mm of rain. This includes the Niagara region and Port Dover/Long Point as well as Prince Edward County extending into Belleville and Kingston. This region can expect between 40 and 60mm of rain with local amounts as high as 75mm, especially with thunderstorms. Further east including Westport, Brockville, and Cornwall, rainfall totals between 30 and 50mm are likely.
The Ministry of Natural Resources and Forestry have issued a flood watch for Southern Ontario and a watershed condition statement for Northeastern Ontario. Alongside the ministry, there are multiple conversation authorities which have issued flood watches and warnings and watershed condition statement. A full list can be found on their website.
In their summary, they state, "Seasonal temperatures are expected to continue for southern Ontario on Saturday, with daytime highs reaching +10 deg.C in eastern Ontario, with slightly cooler temperatures for the remainder of the region, and overnight lows at or slightly below freezing.
A strong Texas low pressure system is expected to move quickly through southern Ontario on Sunday, and overnight into Monday, bringing 25 – 40 mm of rain to areas south of a line from Parry Sound to Petawawa. Temperatures are expected to maintain their current trend: daytime highs between +5 and +10 deg.C, and overnight temperatures nearing zero.
The latest snow survey from April 1st shows a continuing snowpack in southcentral and northeastern Ontario ranging from 100 to 200 mm of snow water equivalent. Station reports indicate the snow is compacting due to the diurnal freeze-thaw and recent rain events appear to be maintaining the stored water equivalency in the snow pack."
Following this system, we look at the end of this upcoming week for another impactful storm which will affect a large portion of the province. Check back for updates on that next system.
Also, check out our partners at TransCanada Weather, which, we partner-forecast for. Here is their forecast for the same system: https://transcanadaweather.ca/2019/04/12/texas-low-brings-severe-outbreak-stateside-with-sights-set-on-eastern-canada