Tag: Severe thunderstorm

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.
Alberta

Much NEEDED RAINFALL & SNOW to Kick off the…

A potent upper-level system will stall all week across Alberta and Saskatchewan. The unsettled pattern will bring much-needed rainfall, thunderstorms, much below seasonal temperatures, and even accumulating S*** for Banff & Jasper.

Beneficial rainfall will persist all week in Alberta & Saskatchewan as an upper-level system stalls across the region. The heaviest rainfall is anticipated across Central Alberta where 50-75mm+ is expected by Friday. With much of that rain falling between Wednesday and Thursday. Some rainfall is in the forecast for drought-stricken High Level (Northern Alberta) & Moose Jaw (Southwestern Saskatchewan).

The much below seasonal temperatures and a soaking rainfall will make it feel more like the middle of October across the foothills. By Wednesday, temperatures will plummet nearly 10c below seasonal. Continuing through the day Thursday.

DAYS OF THUNDERSTORMS CONTINUE WITH THE THREAT OF SEVERE TUESDAY

Thunderstorms have been an almost daily occurrence over the last several days in the Prairies. The thunderstorm risk is expected to continue this week.

Monday: thunderstorms producing heavy downpours and small hail across Interior British Columbia and Northern Alberta.

Locally strong to severe thunderstorms expected across the yellow shaded area today.

Tuesday: better dynamics for potent thunderstorms across Southern Alberta (Calgary to Medicine Hat). Discrete cells or supercells could be capable of producing damaging winds and large hail.

Wednesday: daytime heating thunderstorm risk moves further East into Saskatchewan.

ACCUMULATING SNOW KICKS OFF SUMMER IN BANFF & JASPER

Between Wednesday night through Friday, accumulating up-sloping snow is expected over the high-elevation topography of Banff and Jasper National Parks. Believe or not, Friday is officially the first day of summer.

Alberta

Convective Outlook: Thunderstorms & Flood Risk

Our forecasting team at TransCanada Weather is cautiously watching long range model guidance. Between Tuesday May 28th – Thursday, June 6th, the evolution of a pattern supportive of heavy rain, severe thunderstorms & unsettled conditions will envelop parts of Canada. Read below to find out where.

PRAIRIES: Unsettled Conditions, Risk of Cold Core Funnels, Threat of Thunderstorms

The Prairies will have to contend with unsettled conditions. Including a pattern that may support the risk of cold core funnel clouds & areas of severe thunderstorms between late May to early June. This is be welcomed news for Alberta; contending with out-of-control forest fires.

GREAT LAKES: Heavy Rain & Severe Thunderstorms

A second area we are watching closely: the Great Lakes/Ontario region. A supportive pattern for flooding and/or severe thunderstorms is possible between Tuesday May 28th to Thursday May 30th.

Abnormally, deep troughing, seasonably deep height-falls, strong waves of low-pressure, concurrent with a southeast ridge. Will bring surges of warm moist air along with supportive wind profiles for severe thunderstorms and/or flood risk. A significant severe day will be possible within this regime across Southern or Northeastern Ontario.

Saturday, May 25th: after Thursday, the next threat for severe across Southern Ontario will come Saturday. Risks across Southwestern Ontario include: isolated damaging wind gusts, large hail & torrential downpours.

Additional considerations: drought conditions in the Southeastern US allowing mid-level dry/warm air to migrate north within stronger circulations. Abnormally-wet southern plains, increasing low-level moisture transport/PWAT values in stronger 850mb flows.

-troy

Quebec

Severe Thunderstorm Risk Pushes East into Quebec

A strong cold front will act as a trigger for isolated severe thunderstorms across the Eastern Townships and Southeastern Quebec Wednesday. Damaging winds, torrential rainfall giving 25-50mm of rain in a short duration, frequent lightning and isolated supercell(s) are risk factors with these storms.

Thunderstorms may track into Northern New Brunswick bringing heavy rainfall and lightning as they begin to weaken and become elevated. 

TECHNICAL ANALYSIS:

A developing area of low-pressure will track out of Northeastern Ontario into Quebec Wednesday, deepening rapidly. An area of height-falls & falling atmospheric pressure will overspread the warm sector, ahead of a seasonably sharp cold front. Temperatures will rise into the mid-20s with dew-points nearing 20c. Pockets of 1500J/kg of CAPE should develop across the warm sector. Largely unfavourable lapse rates will be compensated by a strong tendency for ascent. 65 knot, 500mb flow will overspread the Eastern Townships & Southeastern Quebec – ahead of an amplified, positively tilted trough. A modest low-level jet should be sufficient for moisture transport across the warm sector, and a damaging wind threat. Speed-shear and wind shear will be sufficient enough to sustain long-lived updrafts – well-tilted updrafts capable of rotating. A threat for stronger bowing-linear segments or super-cells exists between 1-5pm. Additional risks, include torrential downpours, frequent lightning and hail in the stronger updrafts.

Timing of the cold front and pre-frontal clearing will be important determining factors considering how severe thunderstorms will be. 

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.

Alberta

Tornado & Damaging Hail Threatens the Edmonton Region

A potent severe weather setup is expected today (July 20th 2018) in the Western Prairies. 

Thunderstorm risk map for today. The highest severe threat is highlighted in red – which includes Edmonton in a risk for tennis-ball sized hail and an isolated tornado. 

Environment Canada Discussion (PASPC):

ALBERTA 

A low pressure system developing in Alberta with an associated trough swinging through west-central Saskatchewan in the afternoon will trigger scattered severe thunderstorms. The main threat with these storms will be large hail. In the northwest section, there is a potential for supercells to develop with the potential of producing a tornado. The severe potential will last into the evening but thunderstorms are expected to persist into the overnight.

SASKATCHEWAN 

A low pressure system developing in Alberta with an associated trough swinging through west-central Saskatchewan in the afternoon will trigger scattered severe thunderstorms. The main threat with these storms will be large hail. In the northwest section, there is a potential for supercells to develop with the potential of producing a tornado. The severe potential will last into the evening but thunderstorms are expected to persist into the overnight.

Environment Canada’s Thunderstorm Outlook for today July, 20th 2018. Highlighting an extreme risk for severe thunderstorms in the Capital Region.

TECHNICAL DISCUSSION

A low pressure system will form south of Edmonton today with an associated cold front extending southward along the northern foothills and warm front through east-central Alberta and into Saskatchewan. Severe thunderstorms will trigger along the cold front early in the afternoon. They will likely be isolated in nature at first, before becoming a severe line of thunderstorms. The warm front will track through the area in the morning followed by a trough in the afternoon. Severe thunderstorms are expected to trigger along the trough in the afternoon. There is the potential for the right conditions to align near and to the east of Edmonton for a tornado to form, with the potential extending into west-central Saskatchewan, albeit, less likely than the risk in Alberta. MLCAPE values are between 1500 to 2200 J/kg with 0-6 km shear values around 30 kt with values up to 40 kt in and around the Capital region in Alberta. RDPS prog tephis are indicating idealized veering hodographs, conducive to tornado development, however, tornado formation in this area will be highly dependent on a few factors: There is the potential that the low level shear will be too much for the marginal CAPE in some areas, essentially shearing the storms apart. As well, on the Saskatchewan side, LCLs are progged to be around 1500 – 2000 m, which is a little high for tornado development, whereas, on the Alberta side, LCLs are progged to be 1000 m, which is more favourable for the formation of tornadoes. In addition, models are indicating the formation of a dryline that will bulge out into the southwestern corner of the Lloydminster region which may also be an area to watch for a tornado to develop in the later afternoon hours.

*Please note this maps and discussions are currently experimental and are not currently operational on Environment Canada’s website. 

Please closely monitor Environment Canada alerts today. Take any warnings seriously and seek shelter immediately. 

We will be monitoring the situation attentively. 

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. 

Manitoba

Powerful Supercells for SE Saskatchewan Bring Tornado Risk and…


An associated warm front will set the stage for parameters conducive for strong Tornadoes today for isolated regions in SE Saskatchewan.

Residents in Southeastern Saskatchewan should be extra vigilant to the sky as the current risk leads to a threat for 1 or 2 strong Tornadoes (EF2+), large hail (nickel to ‘ping-pong’ size) and damaging winds (100-120km+).

As the cells form mainly just west of Weyburn, quick evolution and a track E to ENE as LP (low precipitative) supercells will be prevalent. These cells are representative of large hail (in this case, ‘ping-pong size), and a risk for a Tornado a little after their original formation as shear levels drop a slightly.

As the cells continue to track into Manitoba, the cells will become more of a ‘line’ just across the border into Virden, Melita and Brandon – winds up to 120km/h+ are the main threat and the Tornado threat will diminish rapidly.

Elsewhere, isolated severe cells over a large swath of Saskatchewan and Manitoba are possible.

Amongst the most interesting parameter (one among many) is the LCL (lifted condensation level: represents the lowest level in which condensation can occur). Generally, the strongest Tornadoes in history are between 300-600m. LCL levels, in this case, are somewhat conducive to Tornadoes of EF2 or stronger nature.

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

Manitoba

Risk of Damaging Hail and Tornadoes in the Prairies

Severe thunderstorms possible today (June 14th, 2018) in Southeastern Saskatchewan and Southwestern Manitoba. Isolated severe thunderstorm risk continues across Southern Manitoba throughout the evening and overnight.

A disturbance is forecast to move into Saskatchewan today from Alberta. At the same time, a surface low will be moving northwards from the United States. HIGH levels of energy will build south of an associated warm front.

Although this warm front isn’t expected to make it far north of the border (keeping high amounts of energy stateside), moderate energy amounts, and an environment conductive to severe weather is expected. Including discrete cells and supercells capable of producing damaging wind gusts up to 100km/h, toonie to golf-ball sized hail, and a risk for 1 or more tornadoe(s). Damaging hail is currently what we are most concerned about.

Environment Canada (PASPC) has highlighted the risk for 3-5cm hail, 90-100km/h wind, and an isolated tornado in their “moderate” severe risk zone (highlighted in orange). Please note: these maps are still in the experimental stage.

We will be closely watching an area south of a line from Carlyle to Antler to Souris between 5pm-9pm. An isolated severe threat will continue in southern Manitoba through the evening and overnight, as cells become more linear (MCC – Mesoscale Convective Complex) – increasing a chance for damaging winds, torrential rainfall, hail and frequent lightning.

– TCW