Unusual Weather Events Cause Severe Flooding in Niagara

An unusual weather pattern brought at least three storms one after another to Ontario’s Niagara Region during July and August, unleashing heavy rain that led to flooding in thousands of homes across St. Catharines, Lincoln, and Niagara-on-the-Lake, according to experts.

Many residents in these communities, along with others in Niagara like Niagara Falls and Thorold, are still dealing with the aftermath of these storms that overwhelmed local wastewater systems and caused sewage-filled water to back up into homes.

Geoff Coulson, a meteorologist from Environment and Climate Change Canada, mentioned that there were actually more than three storms; it wasn’t just three major rainfall incidents on July 21, July 27 and 28, and again on Aug. 2.

In reality, multiple storms affected northern Niagara during each of those weather events, he explained.

“It’s one storm after another forming to the west of the affected area and then moving through the area,” he told . “[They] rolled over the same area repeatedly.”

Storms Arrived Back-to-Back

A new term for residents in Niagara to learn: training echoes.

This is a term Coulson shared that meteorologists use to describe a specific weather pattern where areas of thunderstorms or heavy rain continuously move over the same geographic location within a short timeframe. The name comes from echoes observed on weather radar.

“You may get a little break in some cases between one storm cell and another, but they are rather relentless: over a number of hours, a series of these storms hitting the same area,” said Coulson.

The outcome? A sewage system that’s simply overwhelmed by excessive water volumes.

“The water’s got to go somewhere,” said Coulson. That means up through drains into people’s basements.

Michael Pisaric, a professor specializing in geography and tourism studies at Brock University, noted that unlike typical thunderstorms that pass quickly, those convective storms affecting Niagara lined up like train cars, dropping “torrential” rain as they unleashed months’ worth of precipitation within just hours.

The average rainfall for all of July is about 74.2 mm, said Coulson. However, automated observation sites in north Niagara recorded how extraordinary the power of these three storms truly was.

On July 21, Vineland received 85.9 mm while Grimsby Mountain got 108.6 mm (data from another recording station in Port Weller in St. Catharines wasn’t available from that day), stated Coulson.

On July 27/28, Port Weller received 126.9 mm of rain while Vineland recorded 87.8 mm.

On Aug. 2, Port Weller saw an additional 131.3 mm while Vineland had 94.8 mm. “There was just seemingly one series of showers and thunderstorms after another that rolled over the northern part of Niagara Region,” said Coulson.

Volunteers with Team Rubicon Canada carry materials removed from the flooded basement belonging to 93-year-old Mary Winning’s home in St. Catharines on Aug. 9. Her home experienced flooding twice within five days. (Paul Forsyth/CBC)

The strength behind those storms came down to several factors aligning perfectly together.

“We had a lot of humidity at lower levels for all three events; this humidity acts as fuel for storm formation,” explained Coulson.

Additionally we had an unstable atmosphere with rising air currents causing droplets to collide into larger droplets until they became too heavy not to fall downwards,” said Coulson.

The Right Conditions Came Together

“The ingredients all came together,” said Coulson. “It’s very rare to see the same area hit three times within just weeks.”.

St. Catharines Mayor Mat Siscoe informed that no blockages or single infrastructure failures have been identified as causes for basement flooding. However , he pointed out most sewer infrastructure still has combined stormwater and sanitary sewers – meaning extremely heavy rains can lead sewage backup into homes.

Could such destructive storms become commonplace amid growing concerns over climate change ?

Both Coulson and Pisaric mentioned it’s too early for conclusions.

“The flooding magnitude seen recently should only happen once every century ,” Pisaric stated via email while conducting fieldwork on lakes studying climate change from Norway.

“[But] there seems some truth suggesting these events might be happening more often. Insurance claims support this claim.”

Meteorologists are also anticipating an especially strong El Niño effect occurring this year , which Pisaric mentioned could contribute towards wetter conditions across eastern Canada.” This could add intensity among certain summer storms ,” he noted.

Coulson added there’s not enough time yet for what’s known as ‘attribution’ studies regarding these Niagara storms – which assess whether human-induced climate change affects likelihood , frequency , or severity regarding weather events.

“But we do know overall concerns exist about increased warmth possibly leading towards more frequent rainstorms occurring during coming decades,” he emphasized.

Any community throughout Ontario could face similar types experiences compared against what occurred recently within their own summers ,” concluded Couselon.

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