Category: 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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Ontario

Severe Thunderstorm Risk; Brief Cool-Down; Another Blast of Heat…

Conditions will become favourable for the development of severe thunderstorms for a large area across Southwestern, Southern, Central and Eastern Ontario for Thursday, July 5th.

What to Expect
With continued rising temperatures, high dew-points, and daytime heating, a weak front will slice through the aforementioned regions and provide enough instability to bring-about some severe thunderstorms later in the day on Thursday.

While the dynamics are not entirely conducive to significant supercell development, a lack of shear, ultimately, will mitigate rapid intensification and development. The primary risk therefore, with these thunderstorms, will be quick flooding rains (25-50mm).

The greatest threat for severe thunderstorms will likely occur just east of Lake Huron, but likely 15-20km west of the major 401 corridor. The GTA and QEW should remain non-severe (overall) and regions around Cottage Country should receive rain showers.

1 or 2 severe thunderstorms on the northern edge of Lake Ontario cannot be ruled out.

Cool-Down
A brief / slight cool-down (24-27C; less humid; and drier conditions), will arrive for the aforementioned regions on/for Friday, Saturday and Sunday.

What’s Next?
From te brief cool-down outlined above, temperatures are expected to rebound back into the upper 20s and low 30s for the next severel weeks (avg: 29-32C). This time around however, conditions will be less humid than the more recent surge of warmth.

As outlined in our summer prediction, isolated severe thunderstorms will continue across Ontario and Quebec for much of the summer.

Long-Range Outlook: Manitoba, Ontario and Quebec.
Continued above normal temperatures and relatively dry conditions are still expected for Manitoba, Ontario and Quebec. There is some potential for record-breaking heat once again somewhere in the last few days of July into early August for about a week.

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.

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

Ontario

Isolated Severe Storms Slice Humidity in Ontario & Quebec

Scattered thunderstorms are expected across the lower half of Southern Ontario and Southwestern Quebec today (July 2nd, 2018).

A weak cold front will slowly track across Southern ON/SQUE today acting as a trigger for thunderstorms. The frontal passage is not expected to offer much relief from the heat, but will lower humidity to more comfortable levels tonight and Tuesday.

The primary risk with these thunderstorms will be torrential rainfall. Due to slow movement of the frontal passage some thunderstorms may “train” or, regenerate over the same region bringing locally 30-50mm in a short period of time. Additionally, isolated damaging winds are possible – primarily in Eastern Ontario and Southwest Quebec where the greatest risk for severe exists. Small hail between pea and dime size is possible in the more robust updrafts across the entire isolated severe risk zone.

The timing for storm development today, will be between 11am-6pm. We have highlighted localized municipalities – stretching from the Golden Horseshoe into Eastern Ontario in a isolated severe threat.

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Manitoba

Heavy Thunderstorms Expected in Southeastern Prairies

Widespread heavy to severe thunderstorms likely late this evening – continuing into the overnight hours in Southern Manitoba and Southeastern Saskatchewan. 

 

A stationary front this afternoon in Northern Dakota will separate warm, moist air south of the international border, with warm, drier air in Southern Manitoba. Along this front, there is a risk of isolated severe storms in North Dakota this afternoon – staying stateside. 

A deepening system out of Rockies will trigger severe thunderstorms stateside and a second, more significant/widespread risk of thunderstorms this evening/overnight.

Environment Canada (PASPC) Thunderstorm Outlook. Valid 12pm Thursday to 6am Friday. Highlighting the risk for severe thunderstorms. Note: these forecast maps are still experimental and are not currently operational on Environment Canadas website. 

A second wave which is forecast to develop late in the day, stateside, is the one we are watching closely. Moist and unstable air creeps across the border into Southeastern Saskatchewan and Southern Manitoba this evening. The northern extent of the second wave is expected to cross the international border into Southeast Saskatchewan and Southern Manitoba sometime around midnight. 

There is still some uncertainty regarding evolution and timing of this convective complex. Such complexes also known as MCSs or MCCs – Mesoscale Convective Complex; are notorious for producing intense frequent lightning, flash flooding, and damaging to destructive winds. Large hail is also a possibility, during the initial storm development.

The risk moves out of Southeastern Manitoba into Northwestern Ontario pre-dawn Friday into Friday morning.

We will be monitoring the situation attentively into this evening and overnight. 

Ontario

June 30 and July 1: Extreme Humidex Values to…

Humidex values across parts of Ontario this weekend are ‘all set’ to arrive for millions this weekend – just in time for Canada-Day festivities. This will be one of the hottest Canada-Day’s in years.

 

Across Southwestern and Southern Ontario, the hottest of the two days will be on Saturday with humidex values into the 40s; regions north of Toronto and extreme Southwestern Ontario will ultimately top the mid 40s.

Across Eastern Ontario, such as the Ottawa-Valley, the hottest of the two days will be on Sunday, with humidex values nearing the upper 40s to potentially 50C in some regions. Records will certainly be broken by the end of Sunday.

Temperatures across a multitude of regions this weekend will be in the neighbourhood of 32-36C with certain regions in the Ottawa-Valley potentially reaching 37-38C.

If you plan on enjoying the weekend heat – or Canada-Day/weekend festivities – remain hydrated and be fully cognisant of all potential heat exhaustion signs to prevent heat stroke.

Look-out for one another.

Be safe and have an incredible Canada Day!

After this weekend, temperatures will cool slightly but remain consistently warm for quite some-time. Watch for drought-like conditions for Ontario and Quebec for the remainder of the summer, overall, with intermittent periods of isolated severe thunderstorms.

For a quick view regarding our updated Summer Forecast from a few days ago, please view the image below.

Updated Summer Temperature Forecast.

 

TCW

Alberta

Updated Summer Forecast: Heat Expected to Dominate Ontario, Manitoba…


2018 Canada Summer Outlook and Higlights Depicted Below —- July and August

Key Highlights

– Heat Builds for Northern, Southwestern, Southern, Central and Eastern Ontario and Southern Quebec Beginning June 29th.

– Many Canadians are Expected to Receive a Warm or Hot July 1st (Canada Day!).

– Unusually Dry for Ontario and Quebec.

– Intermittent Rounds of Isolated Severe Thunderstorms for MB, ON, and QC.

– Decently Warm for SK and AB; Some Periods of Very Warm to Hot Weather.

– Wet BC Coast; Warmer and Drier Interior.

– Newfoundland and Labrador Likely to be Disappointed this Summer Due to Cooler and Wetter Conditions.

– ‘Bone-Dry’ for the Yukon, NWT, and Nunavut.

*Some Potential for Record-Breaking Heat (the Upper 30s) for Parts of ON and Parts of QC for the Last Week of July or 1st Week of August.

Brief Discussion

We at TCW are expecting overall, the country to be slightly above seasonal for the majority of the two months. We expect consistent heat to surge into Manitoba, Ontario and Quebec. While the heat will be slightly less humid as is typical, the heat will be quite consistent for the months of July and August.

It is expected that Manitoba, Ontario and Quebec will be quite dry for these two months, but, become inundated with intermittent days of isolated severe thunderstorms as a result of day-time heating.

The Maritimes are expected to warm-up as the summer progresses, while Newfoundland and Labrador is expected to remain cool and somewhat wet.

Saskatchewan and Alberta will have a few periods of hot weather (especially Saskatchewan), however temperatures will overall, be more warm to very-warm than hot.

British Columbia will remain seasonal and wet near the immediate coast, with the interior being drier and a few degrees above seasonal.

The Yukon, NWT and Nunavut will be slightly above seasonal and very dry.

– TCW

Ontario

Severe Thunderstorm Risk Builds in Southern Ontario

Showers and a risk of severe thunderstorms for Southern Ontario. Heavy rainfall from East of Lake Superior to the Quebec border Wednesday (June 13th, 2018).

A strengthening low pressure system will track East of Lake Superior through the Nickel Belt Wednesday, bringing a risk for heavy rainfall for Northern Ontario and a risk of severe thunderstorms in Southern Ontario. 

WHAT’S EXPECTED 

A swath near the low track, from East of Lake Superior to the Quebec border will likely see rainfall amounts of 25-50mm between Wednesday morning to evening. 

Further south, across Southern Ontario – there will be 2 rounds of precipitation. The first, along a warm front as it edges north into Southwestern Ontario, bringing scattered showers Tuesday evening through Wednesday morning. Once the warm front moves north, there will be a clearing allowing for sunny breaks and energy to build ahead of a cold front acting as a trigger for thunderstorms Wednesday afternoon. Some of these thunderstorms may be severe with damaging winds as the primary threat.

A window for a low tornado threat is possible from mid to late afternoon in our red highlighted area. The greatest threat will be along a “triple-point” – between 1pm and 6pm. This region may expand to include municipalities near the Lake Ontario shoreline. 

Environment Canada (OSPC) is calling for a “moderate” risk of severe thunderstorms. The primary threats according to their risk map is damaging winds up to 100km/h. Please note: these maps are still in the experimental stage. 

STRONG WINDS

After the passage of the cold front the low will continue to deepen as it moves into Quebec. Strong wrap around winds will develop Wednesday evening and overnight. Gusts between 60-80km/h are expected across much of Southwestern, and South-central Ontario. Localized gusts to 90km/h are possible in higher elevation South of Georgian Bay, as well as, near the lakeshore. 

Ontario

The Remnants of Tropical Storm Alberto Approach the Great…

Alberto has been blamed for flash flooding, mudslides and power outages in parts of the Southern United States. The remnants of Alberto will churn into Michigan this evening – increasing humidity readings and creating unsettled conditions for Southern Ontario, beginning late this evening.

High dew-point values will envelop much of Southern Ontario Wednesday through Thursday. Overnight lows near or above 20C Wednesday night, coupled with dew-points in the high teens, will lead to stifling conditions in doors for residences without air-conditioning or central-air.

High humidity with temperatures in the middle to high teens will act as fuel for Thunderstorms Wednesday night in Southwestern Ontario – with a widespread risk for Thursday morning through evening for the rest of Southern Ontario.

The remnant low of Tropical Storm Alberto will act as a trigger Wednesday night and Thursday. As the remnant low approaches Michigan, bands of showers and thunderstorms will wrap around the low.

What is left of Tropical Storm Alberto as it churns north – towards Michigan. Still displaying well defined circulation and heavy rainfall. 

On Thursday, the low will coalesce will a cold front and get absorbed by the Jet-stream. Upper-level energy and a cold front is expected to act as a trigger for widespread thunderstorms, some of which could turn severe. The primary risk with any thunderstorms that develop Thursday will be torrential rainfall and gusty winds. We will be watching Southwestern Ontario where rainfall could be an issue with minor flooding concerns.

A secondary cold front passage is expected Friday – which may act as a trigger for another round of thunderstorms. Again, rainfall will be the primary concern. Small hail is also a possibility.

It’s important to note, the next couple days aren’t expected to be a wash-out for everyone. Some locales may only see a few millimetres of rain. Whereas other locales, who receive several rounds of thunderstorms or training thunderstorms, could see locally 50mm or more.

Some solace from the humidity is expected by Saturday. Temperatures return to normal with brilliant sunshine and no humidity.

NORTHERN ONTARIO

A deep-layer of tropical moisture will move well north into Canada. Reaching as far North as James Bay and Northern Quebec. Heavy rainfall is expected along a boundary between Lake Superior and James Bay continuing into Northern Quebec. Totals rainfall amounts between 40-75mm are expected in the next 48 hours in the region.

Ontario

Thunderstorms, Locally Heavy Rainfall & Frequent Lightning for Southern…

Rain and thunderstorms expected early Tuesday (May 15, 2018) in Southern Ontario.

A complex of rain and thunderstorms is developing this hour in the Midwestern United States. This weather system is expected to push East late this evening, bringing widespread rain and thunderstorms after midnight.

Ahead of this system, humidity levels will increase – with temperatures into the high teens lingering late this evening and overnight.

TIMING:

Windsor to Goderich approximately 1am Tuesday.

Port Rowan to K/W to Shelburne approximately 3am Tuesday.

GTA to Barrieapproximately 4am Tuesday.

Peterborough to Eastern Ontarioafter 5am Tuesday.

Kingston to Ottawa approximately 9am Tuesday.

IMPACTS:

Heavy rainfall and frequent lightning for communities impacted by the complex of rainfall and thunderstorms tonight. A lessor threat for small hail and gusty winds also exists.

Due to already saturated soil, and rainfall intensity, a Special Weather Statement has been issued north of Lake Erie.

Rainfall totals between 20-40mm is expected north of Lake Erie. Locally, up to 50mm is possible. Elsewhere, expect 15+mm.

——

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– TCW

Ontario

First Noteworthy Severe Thunderstorm Risk in Ontario for 2018


For the first time in the 2018 season, a risk of widespread thunderstorms across Ontario could occur on Friday, May 4th, 2018 – some potentially severe.

Synopsis
During Friday morning, many regions across Southwestern, Southern and Central Ontario will experience widespread moderate rain: an isolated non-severe thunderstorm cannot be ruled out. As the morning and day progresses, conditions will become drier, sunny at times, more humid and potentially lead to some severe thunderstorms. The severe thunderstorms that do occur will bring mainly a wind threat.

A somewhat secondary line of isolated severe thunderstorms could also sweep into eastern sections of the Niagara region as a linear set-up of storms will form near upstate Pennsylvania and western New York state; where this line of storms exactly forms will be incredibly relevant for this region. Should it form quickly and near the CAN/USA border (as current atmospheric parameters suggest), the region will be impacted; a formation more eastwards will reduce the risk and impact substantially, to virtually nil.

Potential Severe-Threat Timing
Afternoon to early evening from west to east.

Scientific Analysis
The greatest risk for isolated severe thunderstorms can be depicted in the ‘darker orange region’.
A slight risk for isolated severe thunderstorms can be depicted in the ‘lighter orange region’.
Mainly non-severe thunderstorms can be depicted in the ‘yellow region’. One or two severe thunderstorms cannot be ruled out in this region, particularly along HWY 402, HWY 403 near Brantford and HWY 401 near the London-Woodstock corridor. Later on Friday, it is possible along eastern sections (ex. Kingston to Brockville and 50-60km east of Ottawa), an isolated severe thunderstorm is also possible.

Sufficient atmospheric energy at the immediate surface, as well as, 100mb and 300mb above the surface (SB, ML and MU CAPE) could be adequate to lead to severe thunderstorms. While energy is not astronomically high, and lower in comparison to the more traditional summer months, relatively strong dynamic forces should act as a sufficient trigger for isolated severe thunderstorms. Convective inhibition (CIN) at the surface as well as 100mb above the surface (ML-CIN), should reduce the risk of severe thunderstorms, and thunderstorms all together along the immediate northern shoreline of Lake Ontario: this will lead to cells rapidly weakening as they form near or just east of Lake Huron and usher eastwards. A relatively moderate lifted index (LI) will aid in dynamic instability leading to the greatest threat of isolated severe thunderstorms particularly near or just inland of Lake Huron and SE Georgian Bay. Storm relative helicity (SR) remains weak at the 0-1km threshold, and slightly stronger at the 3km threshold; this will allow for an increased threat of isolated severe thunderstorms in more of a linear format (although not encompassing a large area). Cyclonic updraft at the surface is virtually non-existent at the 0-1km threshold thereby limiting any tornado touchdown to virtually nil.

Other parameters including: Bulk Richardson Number, Cross-Totals, Total-Totals, Thompson Index and shear at the high atmosphere (6km) support isolated severe thunderstorms; although not super-cells; with a risk for strong wind gusts mainly to 90-100km/h as being the primary threat.

Non-conducive lapse-rates and wet-bulb zero (WBZ) coefficients will mitigate the hail risk overall to pea-size to nil.

Precipitable water (PWAT – surface to 300mb) is somewhat low for ‘torrential downpours’, therefore, residents should be spared a ‘flooding risk’ as typical with some severe thunderstorms.

Ultimately, the deepening of the approaching low-pressure system will be well-timed with strong uni-directional winds aloft, 500mb height-falls, and a jet-streak. Further, a sharp cold front is expected to eject through Southern Ontario between ~2-6pm thereby providing a trigger for these thunderstorms.

Across much of Southern Ontario, residents can expect winds gusting to 80km/h for many regions and locally up to 100km/h, irrespective if regions see thunderstorms or not.

Tie down loose patio furniture, patio umbrellas and chairs.

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.

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