Devastating flash flooding on the West Island

Heavy rain from strong thunderstorms quickly overwhelmed the sewer system, inundating roads across parts of the West Island on Saturday afternoon. (West Island Community Page via Facebook)

Powerful moisture-latent thunderstorms swept across parts of the West Island and South Shore on Saturday afternoon, producing nearly two month's worth of rainfall in just a few hours. The slow moving thunderstorms impacted a relatively small area of the Island of Montreal, focusing on Pierrefonds-Roxboro, Pointe-Claire and Dollard-Des Ormeaux. In those communities as much as 170mm of rain fell between 3 pm and 7 pm.

Heavy rain also fell in Dorval, with 60mm at Trudeau Airport. In stark contrast, I only measured 5mm at my weather station here on Ile Perrot.

The result of the torrential rain was immediate, with several main roads, including Highway 40 between Sources and Saint John's Boulevard becoming inundated with water and impassable. Drivers became trapped in their cars by rising flood waters, with at least 15 requiring rescue by Montreal Firefighters. Montreal Division Fire Chief, Martin Guilbault, said his department responded to nearly 800 calls within the first hour of flooding and close to 1200 overall.

At least a dozen communities have been impacted by devastating flooding, affecting hundreds of homes and vehicles.

The Montreal Fire Department responded to over 800 calls in  first hour after the flooding began. Above the department arrives to rescue drivers trapped in their vehicles on Gouin Boulevard in Pierrefonds. (Photo Peter Turnbal)

Nearly four hours of lightning at Trudeau Airport, resulted in a ground stop for safety reasons. Dozens of flights were canceled or delayed and at least 25 incoming flights were diverted to other airports. Between 3 pm and 7 pm it was a constant rumble of thunder to my east over the West Island as dark clouds moved from northwest to southeast and onto the South Shore.

Hail and strong wind gusts also occurred with the storms. As a result of the flooding, Hydro-Quebec needed to cut power to most of the affected area. That combined with other storm effects, such as wind and lightning, resulted in the loss of power to over 25,000 customers. Most of the power was restored early Sunday according to  media relations spokesperson Paule Veilleux-Turcotte.

At least 300 homes were severely damaged by flood waters, but that number is likely much higher. The clean up began in earnest on Sunday, but was interrupted by more weather warnings and thunderstorms. Sunday's storms were a little more tame, as the Atlantic Canada system began to weaken. They still managed to dump heavy rain over the area, with 16.2mm on Ile Perrot in just 30 minutes. That storm also produced hail and strong wind gusts.

As Saturday's storms moved onto the South Shore, more significant flooding and road closures occurred in Saint-Constant, La Prairie, Chateauguay and even as far south as Napierreville.

The thunderstorms were the result of deep moisture pinwheeling around low pressure located over Atlantic Canada. It was the same storm the brought heavy rain and severe weather to Ontario and Quebec last Thursday.

Strong thunderstorms produce flash flooding in parts of Montreal and South Shore

Flash flooding in Pierrefonds on Saturday afternoon. Strong thunderstorms have been moving over the same area for several hours now producing torrential rain, in some cases in excess of 100mm from Laval southeast across Montreal and onto the South Shore. (Photo: Luka Korda via West Island Community Page)

Severe Thunderstorm watches and warnings for southwestern Quebec including metro Montreal through this evening.

Strong thunderstorms have been moving southeast across portions of Laval, through Pierrefonds, Dorval and central portions of the Island of Montreal and onto the South Shore Saturday afternoon, producing widespread lightning and torrential rainfall. Radar estimates and reports form local weather stations are indicating anywhere from 30mm to as much as 100mm has fallen in the last several hours.

At Trudeau Airport, 32.1mm has fallen in the last few hours, with nothing at my weather station on Ile Perrot.

The storms are training over the same region. Flooding has been reported in Pierrefonds and well as on the South Shore in La Prairie and Saint Constant. Several roads have been inundated, while others have significant water accumulations.

Radar is showing more storms developing over the lower Laurentians moving into the Montreal region. Remain vigilant this evening especially after dark. Do not attempt to cross flooded roadways.

Hydro-Quebec is reporting outages to just over 9000 customers at 5:40PM

The showers and storms should weaken after sunset, but more are expected on Sunday. The culprit is strong low pressure over Atlantic Canada sending disturbances in the atmosphere pinwheeling into our region. Conditions should improve Sunday night. 

Radar shows a plume of thunderstorms extending from Laval onto the South Shore. They have been dumping torrential rainfall over the same sections of the city, with 30mm to as much as 100mm falling just in the last few hours.

Another unsettled weather weekend for southern Quebec

The weather has been very active over the last few days in Montreal, with plenty of gusty winds, showers and thunderstorms. Sadly this trend will persist into the upcoming weekend. The tree above tumbled across a Pierrefonds road during Wednesday afternoons storm that hit the West Island. That storm also cut power to more than 60,000 Hydro-Quebec customers. (Photo: Jessica Wasserscheid)

That big low pressure system spinning its way slowly down the St. Lawrence Valley early Friday morning, will continue to influence our weather through the upcoming weekend. Unfortunately that means another weekend where we will be dodging frequent showers and thunderstorms.

The system is strong for June, producing very low barometric pressure readings in southern Quebec, strong wind gusts and plenty of rain and thunderstorms. Fortunately for Montreal, the strongest thunderstorms remained over eastern Ontario, southward into Upstate New York and New England. On Thursday, several tornado watches and warnings were issued in Eastern Ontario as well as Vermont. At least one potential tornado occurred near Woodstock, Vermont and there was rotation observed near Alexandria, Ontario. In the Vermont storm, extensive damage and power outages occurred. Vermont power outages reached over 20,000 Thursday afternoon.

In southern Quebec, winds gusted a high as 70km/h, slowing recovery efforts from Wednesday's storms. Power remains out to just over 5500 Hydro-Quebec customers Friday morning.

In Montreal, it was rain and plenty of it. Another 30-60mm fell across the region. I measured a storm total of 33.2mm on Ile Perrot, bringing my monthly total to 105mm. Trudeau Airport sits at 85.4mm for the month. So if you thought it was a wet June, you would be correct.

Friday will be breezy in Montreal once again, up to 50km/h from the west, along with a few breaks in the clouds. A few disturbances will rotating around the main storm located over the Gulf of St. Lawrence, producing scattered showers and afternoon thunderstorms through at least Sunday. High temperatures will remain cooler for late June, near 20C (68F), perhaps warming into the middle 20s Sunday. Overnight lows will be in the middle teens. 

Another 10-20mm of rain may fall over the next 48 hours, perhaps more in thunderstorms. No severe weather is expected for our region, but gusty winds may accompany any showers or storms.

Airport delays - power outages caused by storms - more expected Thursday

Hail covers the ground in Saint-Louis-de-Gonzague southwest of Montreal during strong thunderstorms Wednesday afternoon. More storms are expected on Thursday. (Photo: Amy Reynolds via Facebook)

A round of strong thunderstorms Wednesday afternoon impacted the extreme southwestern corner of the province, including the West Island portion of Montreal as well as Ile Perrot. The intense cells moved northeast from the New York state border region, later weakening over Laval by late afternoon.

The storms resulted in the loss of power to more than 60,000 Hydro-Quebec customers at the height of the outage. That number was down to 80 breaks Thursday morning, totaling just over 11,000 customers. Most of the damage to the power grid was caused by lighting strikes. Power was also out at Trudeau Airport and most of Dorval, resulting in major flight delays during the late afternoon hours.

The storms also produced significant hail across the region from Ile Perot southwest towards Valleyfield.

On Thursday morning, strong low pressure is lifting across the Great Lakes early, forecast to move north of Montreal to lie near the Gulf of Saint Lawrence on Friday. A warm front will produce heavy rain Thursday morning, followed by a break in the early afternoon. It will be a muggy day, with temperatures in the low 20s.

The trailing cold front will produce strong thunderstorms late afternoon in Montreal, with the risk of  gusty winds up to 90km/h, more hail, lightning and torrential downpours. The unusually strong June low pressure will also generate brisk winds outside of thunderstorm activity, gusting up to 70km/h into the evening hours and 50km/h on Friday. 

Wind warnings are in effect across a large portion of upstate New York and New England and may be extended into southern Quebec. Heavy rain with the storm has prompted warnings north and east of Montreal for up to 80mm of rain. Montreal can expect storm totals of 25-50mm. As of 8AM, 13mm had fallen here on Ile Perrot.

Strong winds both today and Friday may result in isolated tree damage and scattered power outages across the province.

Another round of rain and thunderstorms for Montreal

Just about every other day this month has featured some form of rain or thunderstorms across eastern Ontario and southwestern Quebec. Some have been forecast, while others seem to pop up out of nowhere. Sadly this trend is expected to continue through  the upcoming weekend. (Valley Weather Photo)

Strong low pressure for June is forecast to deepen as it lifts northeast form the Midwestern United States down the St. Lawrence Valley towards Quebec City over the next 24-36 hours. This storm system on the weather maps is more typical of a winter storm and not one you would expect to find in June. That being said, only liquid precipitation is forecast, as it is June!

On Wednesday, clouds will begin to increase as a warm front associated with the storm moves northeast. A few showers and thunderstorms are expected ahead of the main event on Thursday. While no severe weather is anticipated Wednesday in Montreal, some heavy rain will be possible with any storms that develop.

Thursday will be a more active day, with a round of heavy rain in the morning, with as much as 30mm possible for Montreal. A few breaks in the cloud will stir up afternoon showers and thunderstorms, some with torrential rain, gusty winds and small hail. The activity should diminish by sunset. 

Rain totals over the next 4 days could easily surpass 50mm for some locations in our region. Heavy rainfall warnings are currently in effect from Sorel-Tracy towards Quebec City along the north shore of the St. Lawrence River.

Temperatures will remain in the middle 20s both Wednesday and Thursday, with overnight lows in the teens.

Gusty winds will develop with this storm system, even outside of thunderstorm activity. The winds will back from southeast to southwest on Thursday, gusting between 30-60km/h.

As the storm system moves towards the lower St. Lawrence River Valley, it will begin to slow, resulting in stubborn clouds, scattered afternoon showers and chilly temperatures for mid-June. These conditions will persist into Sunday, before yet another storm system approaches for the start of the new work week.

June has already been a wet month in Montreal, with rain falling on more than half the days already. Amounts range from 60mm (2.3 inches) to more than 100mm (4 inches) to date across the southern portions of the province. At Trudeau Airport, 61.1mm has fallen, while I have measured 73.2mm at my weather station on Ile Perrot.

Dry weather with seasonable seasonable temperatures should return for the St Jean Holiday by next Wednesday. 

Increasing heat, humidity and thunderstorms for Montreal

A warm and humid airmass will invade southern Quebec through the end of the week. Humidex values will soar into the middle and upper 30s. Some heavy showers and isolated thunderstorms are possible, with 25-50mm of rain falling for some locations. (Valley Weather Photo)

Severe Thunderstorm Watch in effect for Southern Quebec including metro Montreal for Wednesday.

A few strong thunderstorms are possible late Wednesday and again on Friday across Southern Quebec.

A summery airmass will move into southern Quebec through Sunday, with increasing heat and humidity as well as showers and thunderstorms. A warm front will lift across the region on Wednesday, accompanied by showers. Late today, increasing humidity will lead to scattered thunderstorms, some may have heavy rain and gusty winds. High temperatures will remain in the middle 20s Wednesday in Montreal, rising into the upper 20s to near 30C through Saturday. Overnight lows will remain on the warm and muggy side, near 21C (70F).

Cooler air arrives by late Sunday along with more widespread showers and thunderstorms. Highs will drop into the low 20s. Much cooler air will move into southern Quebec early next week, and is showing signs of remaining in place through the end of the month. Highs will be in the low 20s, with morning lows in the low teens.

A rotating shelf cloud southeast of Winnipeg near the community of Ste Anne, Manitoba, likely produced a tornado on Tuesday afternoon. It was part of a significant severe weather outbreak across Saskatchewan and Manitoba including torrential rain and large hail. (CBC)

Severe Weather in Manitoba & Saskatchewan

A significant severe weather outbreak occurred on Tuesday afternoon and evening across southeastern Saskatchewan, Southern Manitoba and adjacent North Dakota. In Saskatchewan, a tornadoes were reported at North Portal, Alemeda and Oxbow, with significant damage occuring. Heavy rain and tennis ball size hail was also observed. 

Storms were more widespread in Manitoba, with tornadoes observed near Ste Anne and Otterburne. Funnel clouds occurred across the Red River Valley. Hail the size of tennis balls fell in numerous locations. Torrential rain fell with the storm cells, causing widespread flash flooding across the southern portions of the province, including Winnipeg. Over 250mm fell in Stonewall, with 117mm at The Forks in Winnipeg. Winds gusted to 94km/h in the city as well. A peak non-tornado wind gust of 130km/h was recorded at Dand and Deloraine. Wind and hail damage as well as flash flooding occurred and is still being assessed on Wednesday.

Widespread tornado watches were in effect from Saskatchewan into northwest Ontario on Tuesday. The severe weather, though less intense, will shift into southern and eastern Ontario on Wednesday.

Wet, muggy weekend on tap for Montreal - hot next week

Rainfall forecast for the weekend can be a nuisance, however it is much needed. Many municipalities across southern Quebec have some form of watering restrictions in place, including Vaudreuil-Dorion, where it is completely prohibited.

Some much needed rainfall is on the way for Montreal and southern Quebec, unfortunately falling over the upcoming weekend. This seems to be a trend developing, with pleasant weather during the week and rainy weekends. That being said, I don't believe this weekend will be a washout.

Stubborn cloud cover and filtered sunshine is keeping temperatures a little cooler than forecast on Friday. The current temperature is 24C (76F) in Montreal, while Ottawa sits at 29C (85F). A frontal boundary will slide across the region overnight and Saturday, tapping into warm, moist air from the Gulf of Mexico, allowing for frequent showers and isolated thunderstorms Saturday. Any clearing that does occur will make conditions more unstable and lead to additional showers and storms. The same is true for Sunday. Some of the showers may produce heavy rain at times. Small hail, lightning and gusty winds are possible as well, but the risk is slight. As we witnessed last Sunday, it only takes one thunderstorm cell or two to creates problems.

High temperatures both days this weekend will be in the middle 20s, with overnight lows in the teens. Warmer, increasingly muggy weather returns next week, with temperatures again rising to around 30C (86F) by Tuesday and maybe the low 30s through Thursday.

The rain is welcome, especially for those towns and cities restricting watering. Many municipalities are evoking water restrictions this summer to help conserve drinking water, so check with your municipality before you water the lawn. In Montreal, major repairs to infrastructure will result in water shortages. As a result residents are being asked to conserve water, especially when it comes to lawns, swimming pools and washing your vehicles.

In the case of Vaudreuil-Dorion, outdoor watering is completely prohibited year-round since January 1st of this year. Fines range from $250 up to $2000 for individuals and up too $4000 for businesses. This includes automated sprinkler systems. Washing vehicles is allowed, as long as the hose has an automatic shut-off nozzle.

With May behind us, it is safe to say it was a rather chilly month. The data backs that up, with an average temperature of 13.3C (56F), which is slightly below the long-term average. Recent years have seen very warm and dry weather in May for Montreal, so this year seemed rather unusual. Below normal rainfall occurred, with 78mm falling at Trudeau Airport.