Tag: Ontario

Manitoba

Winter Storm to Bring Blizzard Conditions Throughout Thanksgiving Weekend…

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.


Projected snowfall totals between Thursday, October 10th to Sunday, October 13th

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.


Projected snowfall totals between Thursday, October 10th to Sunday, October 13th

ICE STORM

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.


Projected freezing rain totals between Wednesday (pm), October 9th to Sunday, October 13th

RAINFALL

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

Alberta

Long-Duration Snowstorm Brings Early Season Chill Across British Columbia…

A strengthening Colorado Low will bring a long-duration, widespread snowstorm to portions of British Columbia, Alberta, and Saskatchewan before lingering into Manitoba and Northern Ontario.

A weak low is expected to bring a snowstorm to the mountains of British Columbia and Alberta on Friday lasting through to Sunday. Strengthening into the weekend, on Saturday, a strong low is expected to form near the Wyoming/Colorado border before moving east towards Northwestern Ontario before phasing out and reorganizing into a low which will bring widespread rain to portions of Northeastern and Southern Ontario.

WESTERN PRAIRIES & SOUTHERN BRITISH COLUMBIA SNOWFALL TOTALS

Accumulations from the snowstorm will vary greatly throughout Southern Alberta/Saskatchewan with the heaviest accumulations throughout the mountains. Current guidance suggests snowfall totals will be highest between 30 and 60cm, locally higher towards 70cm+, in the extreme southwestern portion of Alberta throughout Waterton Lakes National Park towards Pincher Creek, where the extent of red is shaded in the forecast map. Isolated totals near 100cm may be possible. Along the United States border extending into the mountains, highlighted in pink, snowfall totals between 15 and 30cm are likely with pockets of snow towards 40cm possible throughout the mountains. The highest snowfall totals are due to the position of the low creating an ‘up-sloping’ event where the snow is driven up and into the mountains and foothills allowing for significant accumulations. Snowfall ratios in this region will likely peak around 10:1 (10 inches of snow for 1 inch of water).

Down the mountains into the foothills and into the Central-Northern Rocky Mountains, Purcell Mountains, and Northern Selkirks Mountains, snowfall totals will be limited to 10-20cm with local totals towards 20-30cm. This includes Banff and Cranbrook, as well as, this region is highlighted in purple on the forecast map. In Extreme Southern Alberta, outside of the foothills will likely see between 10-20cm of snow. This includes the City of Lethbridge extending towards the southeast, also seen in purple on the forecast map. The snowfall totals may significantly drop off outside of the mountains and foothill regions as temperatures on Saturday through to Monday across the lower Prairie regions will be within 2 degrees of 0, meaning, snow may change over to rain at the lower elevations. This would significantly limit accumulations. The temperature change would be most prevalent in Extreme Southeastern Alberta into Southern Saskatchewan. Snowfall totals in this region are expected to be between 5-15cm are likely, which can be seen in purple on the forecast map, and circled. If temperatures trend cooler for this region, 10-20cm wouldn’t be out of the question for Southern Alberta and Southwestern Saskatchewan, extending as far in to include Shaunavon. Snowfall ratios will peak around the 3:1 and 5:1 range.

A general 5-15cm, locally up to 25cm, can be extended throughout the Rocky Mountains from the Lake Lousie region northwest into British Columbia extending towards Fort Nelson, as well as the Southern Selkirks Mountains and portions of the Monashees and Cascade Mountains. This would include Jasper and Grande Cache. This is highlighted in dark blue on the map. Across Southern Alberta and Southwestern Saskatchewan, a widespread 5-10cm, locally 15-20cm can be expected, also highlighted in dark blue. This includes Calgary, Medicine Hat, Swift Current, Rockglen, and Penticton. Elsewhere in light blue, flurries are likely. Snowfall totals around 5cm with local totals to 10-15cm are likely around Kelowna and Vernon. Snowfall totals will range under 5cm with local pockets sticking up to 10cm for portions of Saskatchewan and Central Alberta. Generally, the snow will melt-on-contact for a majority of the event for these highlighted regions, including Red Deer, Regina, and Saskatoon.

Environment Canada has issued widespread special weather statements across Southern, Western and Central Alberta, as well as, portions of British Columbia. Winter storm watches have been issued ahead of the snowstorm for Pincher Creek, Waterton Lakes National Park, Canmore, Okotoks, Cardston, and Fort Macleod regions.

Weather alerts can be monitored on Environment Canada’s website: https://weather.gc.ca/warnings/index_e.html

Projected snowfall totals between Friday, September 27th to Monday, September 30th

MANITOBA & ONTARIO SNOWFALL TOTALS

As the snowstorm producing low-pressure system crosses east, bringing the precipitation with it, light to moderate showers are likely across Southern Manitoba, and most of Northern Ontario. Alongside these showers, a band of flurries to light snow will cross portions of Central/Northern Manitoba into Far Northern Ontario. Snowfall totals less than or near 5cm are likely due to the snow mainly being melt-on-contact. A few pockets across Southwestern Manitoba and into Far Northern Ontario may see local totals towards 10cm. The highest confidence for locally higher totals is circled in red.

Projected snowfall totals between Monday, September 30th to Wednesday, October 2nd

BLOWING SNOW & STRONG WINDS

As the snow falls across the Southern Prairies, increasing wind speeds will bring the threat for hazardous traveling conditions in fast accumulating snow and falling snow. Current guidance suggests wind speeds will range from 30-50km/h across Southern Alberta and Southern Saskatchewan later in the day on Saturday extending through to Sunday morning. During the afternoon and evening on Sunday, winds will likely increase to 40-70km/h before 40-60km/h wind gusts settle in across Saskatchewan, Manitoba, and Ontario as the system weakens and phases out beginning mid-day Monday.

Blizzard conditions are possible.

Blowing snow and falling snow may make travel hazardous on Highway 1, 2, 3, and 4 across Southern Alberta and on Highway 1, 13, 18, 21, and 37 in Southern Saskatchewan.

Manitoba

Powerful Line of Storms Threaten Damaging Winds in Manitoba

Temperatures are set to surge near the 30 degree mark today in Southern Manitoba, once the humidity is factored in it will feel closer to 40 degrees celsius. Relief will come in the form of thunderstorms; atmospheric conditions will be primed for severe weather.

A potent system will track eastwards out of Saskatchewan into Manitoba this afternoon acting as a trigger for severe thunderstorms. Strong southwesterly winds aloft will overspread southeasterly winds at the surface; a summer-time signal the atmosphere is primed to produce severe thunderstorms.

Lets play out how storm evolution will likely occur today.

[Valid 4pm] In this model projection, we see ongoing storms in Southeastern Saskatchewan. Manitoba still largely remains thunderstorm free – until the forcing for ascent arrives and the capping inversion erodes.


[Valid 7pm] Explosive thunderstorm development follows around the dinner hour across Southwestern Manitoba; including Brandon, Neepawa, Morden, and Portage. Quickly growing into a large line of severe thunderstorms that will produce damaging winds up to 110km/h, 3-5cm hail, torrential rainfall, frequent lightning, and the risk of a tornado.

[Valid 10pm] an expansive line of windstorms will progress throughout Southeastern Manitoba. Likely clipping the Ontario/Manitoba border. This severe complex could become a powerful, long-track Mesoscale Convective Complex (MCS); as it transverses North Dakota & Minnesota through the overnight hours.


Note the triple-point – an axis of intersection between a warm, cold and occluded front. South of this intersection point (warm front), storm energy will likely build to a very-unstable value nearing 4000J/Kg. This is the region that will be watching for the potential of a tornado. The risk may continue into southeastern Manitoba through the late evening.

Environment Canada Thunderstorm Outlook valid today. Noting an ‘Extreme Risk’ for Severe Thunderstorms. Navigate to their forecast here.
New Brunswick

Texas Low: Severe Outbreak Precedes Potent Storm for Eastern…

A significant trough crossing the Guadelupe Mountains will drive the development of a potent area of low-pressure across Texas Saturday. Favorable conditions for the development of severe thunderstorms, will exist along the warm front axis; ahead of a vigorous cold front. This will be significant “severe weather event” for Northern Louisiana, Southern Arkansas, Western Mississippi, and Eastern Texas. Reloading for a second day of severe weather, across the Eastern United States.

Moisture laden low developing in Texas bringing severe thunderstorms. With impacts across Eastern Canada to end the week. Persisting into early next week.

During the day Sunday, the low is forecast to take a northeast hook towards the lower Great Lakes bringing a plume of rain and snow for Southern/Central Ontario & Southern Quebec.

Atlantic Canada is poised to see the most tempestuous conditions, with rapid deepening of the low-pressure center late Monday. This system will be a heavy-rain story for the Maritimes. On the contrary, Newfoundland could see heavy snow, significant freezing rain and strong winds.

COOL, WET & LOUSY COUPLE DAYS FOR SOUTHERN ONTARIO

Get out and enjoy the abundant sunshine and warm temperatures Saturday. A messy, moisture-laden system out of Texas will deliver below seasonal temperatures, a soaking rainfall, mixed precipitation and accumulating wet snow. The heaviest rainfall will be situated along the Lake Ontario shoreline into the Niagara Region. The heaviest of the snowfall will be seen across parts of Central Ontario – through cottage country.

A lousy system for the Great Lakes. Below seasonal temperatures, a soaking rainfall and more snow expected.

SIGNIFICANT RAINFALL & GUSTY WINDS FOR THE MARITIMES

Significant rainfall will encompass much of Nova Scotia, the Bay of Fundy region in New Brunswick & Prince Edward Island. There is still considerable uncertainty how this low will develop in the Maritimes. Current projections have most of the precipitation falling as rainfall. As much as, 40-75mm of rain is possible, between Sunday night through Tuesday morning.

Click to navigate a larger image of the map.

POTENTIAL ‘WEATHERBOMB’ FOR NEWFOUNDLAND

The system is expected to undergo rapid deepening Monday night. Slowing as it transverses through Gulf of St. Lawrence. A strengthening wind field along the Northwestern coast, persists all-day Tuesday. Refinements to the forecast will come throughout the coming days. Nevertheless, this is looking like a potent system for Newfoundland.

We are becoming increasingly concerned regarding a freezing rain threat for the north coast of Newfoundland. Including Fogo Island, Bonavista North & Green Bay. 10-15mm+ of freezing rain, ending as snow and strong winds could bring localized power outages.

Heavy snowfall will be the story across Northwestern Newfoundland with as much as 20-40cm falling over the hardest hit areas. Concurrent, with strong winds leading to blowing and drifting snow.

Ontario

A Wintery Mix Supersedes Extreme Cold Across the Great…

Winter returns to the Great Lakes, after an extended lull in activity and cold air between December and early January. Find out where, and, how bad the ‘next one’ will be.

KEY DETAILS

An area of low-pressure tracks through Illinois late this evening. Tracking through Michigan & Northeast Ontario by Wednesday afternoon & evening. Precipitation begins as snow across Central, Northeastern, and much of Southwestern Ontario Tuesday evening.

Freezing rain and ice pellets begin after 9pm across the Windsor – Sarnia corridor. Changing to rain, with little impact. Freezing rain spreads north of Lake Erie through the overnight. 3-6 hours of freezing rain is expected before changing over to rain. 

Snowfall continues across much of Central, Southwestern, and Eastern Ontario overnight into Wednesday morning. A lull in snow develops across the 400 corridor near 7am. Lowering snowfall totals across Southern Simcoe county; risk of freezing drizzle.

South of the 401/402 changes over to all rain during the early morning. Freezing rain continues along the escarpment (West of Lake Ontario). A changeover to rain continues North & East throughout the afternoon, proceeded by brief freezing rain.

Snow continues North of Lake Simcoe and North of Ottawa through the afternoon. A extended period (5-8 hours) of freezing rain develops Wednesday afternoon in Montreal, after a period of snow. Conditions will be hazardous in the City.

Projected precipitation totals across Southern Ontario Tuesday night through Wednesday.

TOTALS

A primarily snow event stretching from Bruce and Huron county’s through Georgian Bay. Also, putting parts of Eastern and Northeastern Ontario in a swath of 15-25cm. Little accumulation north of Lake Erie, but watch for icing with the potential of 5-8mm of accretion before the changeover to rain. 2-4cm of snow across the GTA, with brief freezing rain. A larger swath of 5-10cm of snow is expected across the light blue shaded area on our forecast map.

New Brunswick

Mixed Precipitation for Eastern Canada & First Appreciable Snowfall…

A system developing in the Southeastern United States will track up the Eastern Seaboard this weekend, becoming a weather story across Eastern Canada.

SYNOPSIS:

A developing coastal system will bring a wintery mix across Southern Ontario, Quebec, and Northern New Brunswick. 

A boundary will form in Southern Ontario between a cold & dry high-pressure system, and moist air arriving from the Southeast. Colder air will overspread Southern Ontario and Southern Quebec Saturday, owing to a cold Northeasterly wind. Concurrently, a large area of precipitation will push north into Southern Quebec and Southern Ontario.

Snow, mixing, rain and freezing rain is expected from Saturday morning to Sunday evening. Flurries will continue through Monday.

Across, Nova Scotia, PEI and much of New Brunswick will see primarily rain. Although, Northern New Brunswick could remain as a mix or snow depending on the track of the developing system.

WPC forecasted fronts & precipitation types. Valid Friday evening.

SOUTHERN ONTARIO:

Many residents East of Highway 6 and across the GTA have started the day with moderate wet snow.

A cold northeasterly wind will reinforce colder air by Saturday evening. Mixing or rain-showers will transition into a wintery mix of wet snow & ice pellets east of Highway 6, along/north of highway 407/7. Continuing through much of Central and Eastern Ontario (away from the lake shore). A few wet centimetres is possible. Especially for municipalities at higher elevation South and East of Georgian Bay. Please plan accordingly, as conditions will deteriorate through the day Saturday.

MARITIMES: Strong Winds & Heavy Rainfall

This system will be a rain and wind story across much of the Maritimes. The strongest winds, with gusts between 80-90km/h, will be located across the Bay of Fundy. Elsewhere winds across much of Nova Scotia, PEI and New Brunswick are expected to be gusting between 50-70km/h Sunday morning. Total rainfall amounts between 20-50mm is expected by Sunday afternoon. The heaviest rain falling in Southern New Brunswick and coastal Nova Scotia. Across Northern New Brunswick, a period of snow and mixing may persist into the overnight. 

Forecast precipitation type & accumulation.

QUEBEC:

Flurries will begin north of the St. Lawrence Saturday evening. Montreal, and the Eastern Townships will likely changeover to rain late Saturday evening/overnight, with the arrival of warmer air. 

For regions north of the St. Lawrence, this will be a snow and ice story. Stay tuned to further forecasts Saturday night through Sunday morning, this region could see a 5-8 hour window for freezing rain.

Model depiction showing precipitation types late-evening Saturday, continuing overnight.


Ontario

Another Round of Severe Weather Targets Southern Ontario &…

Monday will be a pleasant seasonal day, dominated by high pressure and brilliant sunshine – across Southern Ontario & Quebec.

Wet, humid and stormy conditions start the week, with a risk of thunderstorms. Find out when and where.

SYNOPSIS:

Cloud, spotty showers, steady rainfall and humidity will make a return to Southwestern Ontario as early as tonight, with a warm front pushing northwards. Overspreading, the rest of Southern Ontario and Extreme Southern Quebec by Tuesday Morning.

Concurrently, an area of low pressure will strengthen along the Manitoba/Ontario border as it tracks towards Hudson Bay. 15-30mm of rainfall is expected in Northwestern Ontario. With wet snow mixing in across far Northern sections. 

2 WAVES OF PRECIPITATION

The first wave of precipitation will arrive overnight tonight into Tuesday morning across Southern Ontario, moving into Quebec by the morning – ending early afternoon. Some embedded heavy-downpours is expended in a swath from the shores of Lake Erie to Niagara. Elsewhere, expect light to moderate rainfall and predominantly cloudy, warm and humid conditions. Dry slot arrives in the late morning to afternoon.

We will be watching Southwestern Ontario closely Tuesday, as any clearing could further destabilize the atmosphere increasing the risk of evening thunderstorms ahead of the cold front.

SECOND WAVE; RISK OF ISOLATED SEVERE THUNDERSTORMS

Associated with a sharp cold front – along a developing strong area of low-pressure forecast to deepen as it tracks through Northeastern Ontario and Quebec.

SOUTHERN ONTARIO

Thunderstorms will develop ahead of a cold front Tuesday night, persisting into Wednesday morning from East of Georgian Bay through Southwest Ontario. Isolated severe storms are possible. Bringing isolated strong wind gusts and heavy downpours. 

SOUTHEASTERN QUEBEC

A risk of isolated severe thunderstorms develops for Extreme Eastern Ontario and Southeastern Quebec late Wednesday morning or early afternoon, ahead of a sharp cold front. The primary risk will be damaging winds and heavy downpours. Isolated supercell(s) cannot be ruled out in Southeastern Quebec, but the risk will largely depend on timing & clearing.

GUSTY WINDS

Gusty southwesterly winds of 40-60km/h will overspread the risk area Tuesday. Becoming northwesterly through Wednesday. The strongest wind gusts of 60-70km/h will remain draped across Central Quebec and Nova Scotia.

Ontario

Potent System: Severe Thunderstorms & Pattern Change for Ontario…

[UPDATED] A strong fall-like system will track across Ontario and Quebec Friday, bringing a risk of severe thunderstorms. Heavy rainfall, strong winds and a pattern change is expected. Find out where.

Through the day Thursday, an area of low-pressure will deepen as it tracks from the Midwest into Northeastern Ontario, Friday morning. The low will mature as it tracks into Quebec by Friday afternoon.

A warm front, associated with the seasonably-deep low will push north across Ontario and Quebec Thursday morning into Friday. Concurrently, temperatures will soar into the high-20s Friday afternoon across Southern Ontario and Southern Quebec (near the border). Increasing dew-points will lead to muggy conditions feeling into the mid-30s.

Instability, very-strong upper-level winds, wind-shear, and marginal energy will lead to severe thunderstorms Friday. Ahead of a vigorous cold front, and strong upper-level trough where heights will be falling.

RISK & COVERAGE

The greatest risk for severe thunderstorms in Ontario will stretch from Central Ontario to Eastern Ontario. Coverage will be more isolated in Ontario than Quebec. These thunderstorms will be capable of producing strong wind gusts. Upscale growth into a squall-line bringing straight-line winds, heavy downpours and frequent lightning is possible.

In Quebec, atmospheric energy & cooler temperatures will be less favorable than Southern Ontario, but better forcing, shear, and instability will lead to isolated-severe thunderstorms. Risks include damaging winds, frequent lightning and heavy downpours. This will include the risk of supercells. The strongest risk will largely affect rural, unpopulated municipalities.

WIND & HEAVY RAINFALL

Regardless of thunderstorms, synoptic winds will be strong across Southern Ontario and Southern Quebec with this fall-like system. Widespread gusts between 50-80km is expected across a large swath of Ontario and Quebec, preceding the cold front and after its passage.

UPDATE: latest model guidance is suggesting that localized wind gusts of 90-100km will impact Ontario and much of Quebec.

30-50mm of rainfall is expected along a swath East of Lake Superior through Northeastern Ontario.

PATTERN CHANGE INTO FALL

The passage of the cold front will usher is much cooler and drier conditions by Friday night. Temperatures will struggle to get into the mid-teens by the weekend. A hard freeze is looking probable across Northern Quebec and Northern Ontario.

Ontario

Isolated to Scattered Severe Thunderstorms for Ontario – Monday,…


A few rounds of Isolated to Scattered Severe Thunderstorms will arrive for a large swath of Ontario for Monday.

Beginning early on Monday, several rounds of severe thunderstorms will arrive for Ontario. While initially on radar, it may look like only certain regions will be encompassed by Severe Weather, there will be a few rounds throughout the day.

The initial round looks to be from Sarnia to Windsor, with a secondary and tertiary line of storms for the rest of Southern and Eastern Ontario mid to late day.

A few severe thunderstorms are also possible early on due east of Georgian Bay.

Key Highlights
– The best chance of severe thunderstorms near the Canada/USA border from a line including Sarnia SW to Windsor; primary risk is wind gusts up to or above 100km/h
– Some indications of isolated cluster cells SE of Georgian Bay, and all along the GTA, as well as, much of Eastern Ontario; primary risks are winds up to 90km/h, small hail and torrential rain
– Elsewhere, a few isolated severe thunderstorms are likely

Remember, summer thunderstorm forecasts  – severe and/or non-severe – represent a plausible scenario based on extensive weather calculations, parameters and up-to-date atmospheric data. Nothing is for certain, but outlines a possible or likely scenario based on the aforementioned points.

Please stay tuned, as we at TCW are monitoring this situation attentively.

Drive safe and always be alert during hazardous conditions.

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https://twitter.com/TransCANWeather

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Ontario

When Will it End? Early April Chill to Bring…


An early April chill will allow colder air from Northern Canada to funnel into much of the continent of North American and provide one residual and last remnant shot of winter; significant accumulating snow April 4th (Night) through April 5th is likely, especially for some regions.

We have prepared a risk map outlining the potential for significant snow (deemed in this case a minimum of 5cm or more), across Southern, Eastern, Central and Northern Ontario, as well as parts of Southern Quebec and the Townships.

At this point, it seems most of the coldest air should remain north of the 401, alongside the higher moisture content; most of the heaviest snow will reside around Cottage Country and near Lake Superior/Northern Ontario.

At this time, the 401 corridor with the exception of regions near Lake Erie, can except a swath of 5-10cm, while regions north of the 401 (and Quebec) can expect 8-12cm, locally 15cm, and regions in Cottage Country, Northern Ontario and Lake Superior region can expect 15-20cm+.

Inevitable = >90%
Very High Chance = 80%+
High Chance = 70%+
Moderate Chance = 50%+
Slight Chance = 30%+
Minimal Chance = 10%+

When will the cold relinquish?
As recently predicted and outlined in our Spring/Summer forecast, it is [and we expect] Spring to be relatively cool across much of Eastern Canada with above normal precipitation. However, we do believe more moderating temperatures will begin to enter the Eastern half of the country beginning very late April, and more prominently into early May.

Please stay tuned, as we at TCW are monitoring this situation attentively.

Drive safe and always be alert during winter conditions.

For hourly and live storm updates around the clock, follow us on Twitter.
https://twitter.com/TransCANWeather