Tag: torrential rainfall

Ontario

Spectacular Shelf Cloud Spotted Near Tilbury Ontario

It’s been an active evening across extreme Southwestern Ontario. Severe storms produced torrential downpours, damaging winds, intense frequent lightning, and eerie skies. One storm chaser tracking the storms got more than he anticipated today.

https://twitter.com/IWeatherON/status/1146217122890223622
There has been some damage and minor flooding reported.
A roll cloud ended the evening of severe weather as the storms became outflow dominated, turning into a large area of moderate to locally heavy rainfall.



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. 

Alberta

[UPDATED] Severe Thunderstorms Possible in the Prairies

Isolated severe thunderstorms are possible today (Monday June 25th, 2018) and tomorrow (Tuesday June 26th, 2018) in the Prairies.

MONDAY:
A cold front will act as a trigger for severe thunderstorms today in Alberta.

The greatest risk for severe will center itself north of highway 43 and along and west of highway 63. Much of the severe activity looks to be staying south of Fort McMurray.

Environment Canada (PASPC) has placed this region in a “severe” risk on their map. Highlighting the risk for 3-6cm hail. Other threats include damaging winds in excess of 90km/h, and frequent lightning.

Environment Canada forecast map for today – highlighting the severe risk in Alberta. Please note: these maps are still in the experimental stage and are not currently operational.

TUESDAY:
A disturbance and associated cold front will move Eastwards out of Alberta tonight into Saskatchewan. The disturbance is expected to deepen as it centres itself over Central Saskatchewan Tuesday Afternoon.

The cold front will act as a trigger for thunderstorms in Eastern Saskatchewan and Southwestern Manitoba between 2pm and 8pm – West to East.

Some of these storms could turn severe with frequent lightning, large hail, torrential rainfall and strong winds.

Environment Canadas Convective Discussion for Tuesday, June 26th.

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

Manitoba

A Weekend of Severe Thunderstorms in the Prairies Persists

Isolated severe thunderstorms expected today (Sunday, June 10th) in Saskatchewan & Manitoba.

Isolated severe thunderstorms are expected to develop in Central and Eastern Saskatchewan beginning by the mid-afternoon and persisting well into the evening hours in Western Manitoba.

We have highlighted an area in orange where the greatest risk develops. Regions is yellow can expect primarily non-severe showers and thunderstorms. Note: this risk continues into Western Manitoba.

Risk factors associated with these thunderstorms include: large hail, torrential rainfall, frequent lightning, and damaging wind gusts in excess of 100km/h.

Much cooler and less humid conditions are expected for Monday.

Severe thunderstorm risk for today expected in the orange section of our map. 

ANALYSIS

A surface low will decent across Southwestern Saskatchewan early in the morning Sunday. The first low has led to rain and heavy thunderstorms in Southwestern areas of the province early this morning. At the same time, a secondary low pressure center/vort max will be deepening as it approaches Western Saskatchewan during the afternoon. A trough in the Jet-stream will be progressing Eastwards across Saskatchewan during the period.

A eastward progressing front associated with the deepening low-pressure system, will act as a trigger from the mid-afternoon through the late evening – across Central and Eastern Saskatchewan.

Deep moisture transport aided by a 30-40kt low-level Jet out of the Southeast will result in dew-points in the high teens. Concurrently, temperatures will likely rise into the high 20s. Convective Available Potential Energy (CAPE) will likely build above 2000 J/KG across the warm sector, providing plentiful energy for strong thunderstorms. Warmer air aloft (a “cap”) will have to erode before storms can erupt – perhaps after peak energy.

Marginal wind shear and helicity readings, little veering with height, and a high LCL is expected to limited any tornado activity despite a south-easterly surface wind. The south-easterly flow and storm mode/track may allow for “training” – which heightens the threat for localized flooding.

Environment Canada (PASPC) has issued a map highlighting Southeastern Saskatchewan and Western Manitoba in a “moderate” risk for severe thunderstorms. Primary hazards include: 110km/h wind-gusts and 3-5cm hail. NOTE: these maps are still in the experimental stage. 

Near the low center (which is expected to exist in the North Battleford corridor), a soaking rainfall and heavy thunderstorms is expected. This activity should remain non-severe. Rainfall amounts of 15-35mm are expected.

The risk for severe thunderstorms continues Eastwards into Manitoba. Reloading again, for Manitoba and Northwestern Ontario on Monday.

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– TCW