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Analysis | Five 1,000-year rain events have struck the U.S. in five weeks. Why?

Analysis | Five 1,000-year rain events have struck the U.S. in five weeks. Why?


Five weeks. Five instances of 1,000-year rain events. If it seems like the weather across the Lower 48 as of late has been bonkers, you’re not imagining things. It’s been a maelstrom of weather extremes, a seesaw fluctuating wildly from significantly dry to record wet conditions.

Parts of the United States, especially in the West, are gripped by an inveterate and devastating drought — yet many drought-stricken areas have experienced rare and extreme flooding over the summer, bringing fiercely different precipitation extremes to the region in a matter of hours.

At least one dead after Dallas area hit by 1-in-1,000-year flood

On Monday, parts of the Dallas-Fort Worth metroplex awoke to torrential downpours that dropped totals of 10 to 16 inches, bringing calamitous impacts and prompting widespread water rescues. Entire neighborhoods near the suburb of Mesquite were left beneath water, and at least one person died.

What happened in the Dallas area came after the city and 29 percent of the state were gripped in a top-tier “exceptional” drought that impacted crops and drove water shortages. Some farmers were forced to thin their herds in a process called “culling,” according to the U.S. Drought Monitor. DFW International Airport was 11.11 inches behind for rainfall since Jan. 1.

Then Monday became the airport’s wettest calendar day on record.

The extreme rainfall in Dallas was a “1,000-year rain event,” an episode of flooding that has just a 0.1 percent probability of happening in any given year. It joins the company of 1,000-year rain events that struck Kentucky, St. Louis, eastern Illinois and Death Valley, Calif., since the end of July — all of which were experiencing abnormally dry conditions or in a severe drought beforehand.

Droughts can often make flooding worse. Droughts kill plants and leaves the ground bare, reducing soil absorption. They also harden top soils, which makes it easier for water to run off. The extremely dry ground, combined with the rapid rainfall, can trigger widespread flooding.

While no single weather event is caused by mankind’s influence on the atmosphere, the weather facing the nation bears the fingerprint of a warming world. While it seems contradictory, both drought and flooding are closely tied to human-driven warming and are altering our environment and how we interact with it.

We are witnessing firsthand the effects of ordinary weather events — a product of chaotic randomness and natural variability — supercharged by climate change.

What is a 1,000-year rain event?

We haven’t been taking measurements for 1,000 years, so how can we know what constitutes a 1,000-year rain event? It comes from constructing what’s called a probability distribution, and requires some basic grade-school statistics.

Using an available data set of, say, 100 years or so, we can plot the frequency of rain events of varying magnitudes for a given time window. Once that’s done, we can note the shape of whatever distribution results. Think back to the bell curve in math class — most of the data is clumped around the middle, with more extreme events on the edges as frequency trails off. Finding the likelihood of an extreme weather event is similar.

From there, meteorologists and statisticians extract “recurrence intervals,” or the average frequency with which a given extreme event should occur. That means a 1,000-year rain event has an 0.1 percent chance of happening in any given year. A 100-year event would have a 1 percent chance, and so on.

Nowadays, however, our climate is evolving rapidly enough that previously-defined recurrence intervals based on historic data may no longer apply. Michael Mann, a climate scientist at Pennsylvania State University, explained that today’s climate is making some of these reference points relics of the past.

“Recurrence intervals start to lose their meaning for ‘nonstationary’ systems,” he wrote, “in this case because there is a trend toward greater extremes in a warming climate.”

Extreme weather tormenting the planet will worsen because of global warming, U.N. panel finds

In a 2017 paper, he found the return period of a 7.4-foot storm surge flood in New York City had decreased from once every 500 years in preindustrial times to once every 25 years since. It could become a once-per-five-year event toward the middle of the century. Precipitation extremes follow a similar trend.

Five 1,000-year rain events in five weeks

It’s normal that somewhere will see a 1,000-year rain each year. It’d be abnormal if that wasn’t the case. But five in five weeks is extreme, and hints at an overarching trend.

  • On the morning of July 26, St. Louis awoke to historic flooding in the city. A staggering 7.87 inches of rain fell in six hours during the morning commute, inundating vehicles and prompting hundreds of water rescues. It came from training thunderstorms, or storms moving along a stalled frontal boundary. A total of 8.64 inches was logged for the day, becoming St. Louis’s wettest day on record. It crushed the previous record of 5.59 inches on May 16, 1995, by a wide margin; records date back to 1931. Some places west of the city received close to 13 inches.
  • On July 27, rains began in eastern Kentucky north of Hazard and quickly turned fatal. Rainfall rates topping 2 inches per hour contributed to rapid rises on area rivers, including the North Fork of the Kentucky River at Whitesburg, which rose 11 feet in five hours. That was six feet above the previous record. The water probably kept rising, but the sensor was washed away. It was another 1,000-year rain event that tragically killed 38 people.
  • On the night of Aug. 1, training thunderstorms in eastern Illinois dumped 8 to 13 inches of rain in about 12 hours near the town of Effingham. Fortunately the landscape was able to handle the rainfall, but there were some reports of flash flooding.
  • On Aug. 5, heavy storms dumped 1.46 inches of rain on Death Valley, Calif. That doesn’t sound like much, but it’s just 0.01 inches shy of the all-time daily record. Given the rapidity with which it fell, it was classified as a 1,000-year rain event. Death Valley averages just 0.11 inches of rain in August; 1.46 inches is equivalent to nine months’ worth of rainfall. According to the Park Service, the flooding destroyed a water system that serves numerous park residences and facilities. A number of vehicles were also damaged.
  • On Aug. 22, moisture pooling on a stalled frontal boundary over Dallas translated to training thunderstorms. DFW International Airport saw both its wettest day and wettest hour on record. Flash flood warnings were issued across the city.

All five events stemmed from stationary fronts and anomalously-humid air masses.

The fingerprint of climate change

It’s well-established that a warmer world is a wetter world. That’s due to something called the Clausius-Clapeyron relation. For every degree Fahrenheit the air temperature warms, the air can hold about 4 percent more water. That’s leading to higher humidity and heat indexes — which can be taxing on the human body — but is also manifesting in precipitation extremes.

It’s not noticeable in the day-to-day, but let’s consider that we take a storm in preindustrial times and copy it into today’s environment. With about 1.8 degrees of warming since preindustrial times, the air would have a 7 to 8 percent greater capacity to store and transport moisture.

In a water-loaded environment like a thunderstorm complex or tropical system, you might think that would mean 7 or 8 percent more rainfall. But that’s where things get murky. Because an air mass is being constantly replenished and fed into these storms, that can quickly lead to a 10 or 20 percent increase in precipitation totals.

We’re seeing this quite prominently in rainfall rates, meaning the wetter atmosphere is leading to heavier instantaneous downpours. Dallas, for example, saw its highest one-hour total on record between 1 and 2 a.m. on Monday, with 3.01 inches coming down. Records at DFW International extend back to 1953, but seven of the top 10 wettest one-hour totals have occurred in the 2000s.

There’s already been a 24 percent spike in the frequency of top 1 percent rainfall events in Texas since the dawn of the 20th century. That trend is echoed across the country and world.

No weather is caused by climate change. Weather will always be weather. But the signature of a warming world is now perceptible every day in the conditions we regularly face.

For many people, the concept of a changing climate might seem distant and removed — a two-millimeter rise in sea levels a year or a subtle uptick in global temperatures may appear inconsequential. But human influence is affecting the dynamics of weather systems, the periodicity of the jet stream and the moisture-holding capacity of the atmosphere.

As is becoming evident in the Lower 48 and across the world, 1,000-year floods may happen a lot more than once every 1,000 years. “Unprecedented” may, in fact, become precedented. And the uptick in extremes and changing conditions means our environment is evolving faster than our infrastructure. That’s the crux of the problem.

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Rain or shine? Not this time — Weather cancels area events – Salisbury Post

Rain or shine? Not this time — Weather cancels area events - Salisbury Post

ROWAN COUNTY — As storms rippled through much of Rowan County over the weekend, many residents were relieved.

After weeks of steadily rising summer temperatures, the opportunity to cool off with a quick summer shower was a welcome opportunity.

Unfortunately, those brief summer showers turned out to be a whole lot more in some parts of the region, leading to the cancellation of multiple events around the county.

The storms included a series of powerful cells bringing lightning and heavy rain that repeatedly swept through Rowan and surrounding counties on Friday evening, with more arriving later on Saturday and Sunday as well.

As a result of this, the Reels & Riffs series had to cancel its screening of “Ghostbuster Afterlife” at City Park in Salisbury on Friday evening.

On Sunday, Kannapolis was forced to take similar measures when another round of rainy weather led local officials to close down activities at Village Park for children and cancelling their own Movies in the Park event as the rain persisted.

The rain also impacted the Kannapolis Cannon Ballers and their ability to start an afternoon game on Sunday, leading to a delay as groundskeepers hurried to protect the field while players and fans alike waited out the weather.

These cancellations have raised questions about just how possible it is to plan outdoor social events in Rowan County when strong storms regularly pass through the region on a consistent basis for the summer season.

Speaking with local officials for Salisbury and Kannapolis, there is a confidence that such events can continue, however, due to a proactive approach to anticipating and planning around any weather-related issues.

Annette Privette Keller, the director of communications for Kannapolis, explained that, “usually our events are rain or shine, but if there is lightning or more severe weather, we will consider a cancellation.”

Keller pointed out that Kannapolis has not canceled any previous movies for the public this year and that this decision was only made after consideration that rain had been falling for hours, the showers were expected to continue, and the temperatures were unseasonably cold.

Vivian Koontz, the events coordinator for Salisbury, said that they take a lot of factors into consideration before deciding how to handle a scheduled event when inclement weather is on the horizon.

Koontz explained that, “summer storms often come with high winds which are dangerous to our movie-goers” and could potentially damage the city’s screening equipment as well.

Salisbury works to assure that when these events occur, contingencies are in place. Whether it involves notifying the crowd in advance so they don’t arrive to find the event canceled, or adding a make-up date on their calendar to reschedule a canceled event, officials are mindful of the possibility for inclement weather.

The impact of these storms may continue in the coming weeks and months as the summer heat and humidity only leads to new storm cells passing through the region, according to the National Weather Service.

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‘1 in 10-year event’: Experts react to severe flash rain events in the Okanagan – Kelowna Capital News

‘1 in 10-year event’: Experts react to severe flash rain events in the Okanagan - Kelowna Capital News

Monday afternoon’s rainfall in the Okanagan was so significant that meteorologists say such an event may not happen for at least another 10 years.

Within 45 minutes between 2 p.m. to 3 p.m. on July 4, more than 12 millimetres of rain fell to the ground in Penticton, prompting the evacuation of 16 homes, 86 structures flooded and the activation of a local state of emergency.

But Environment Canada meteorologist Doug Lundquist says the focus of the event should be more on the “return rate” of the rain, as opposed to overall precipitation statistics.

“All the way from the U.S. border at Osoyoos and to the suburbs of Kelowna, there were storms that recorded a return rate of 10 years, at the minimum,” he explained. “That’s just based on where our weather stations are, though. In all likelihood, the return period is probably even longer than that.”

Though it was Penticton’s emergency operations centre who responded to 86 flood-related calls from residents on Monday, Lundquist says that Summerland actually experienced the heaviest rainfall in the South Okanagan.

Based on the location of the local Environment Canada weather centre, Summerland set its own all-time precipitation record for the day of July 4, experiencing more than eight millimetres of rain in one hour with 15.7 mm in total.

Lundquist added that Osoyoos also broke its own daily precipitation record on Monday (14.1 mm).

While Penticton fell short of setting a daily record, what set the city apart compared to other Okanagan communities was the number of different neighbourhoods that were affected by the heavy amounts of rain.

“What’s unique about this is for Penticton that the most severe weather hit right where people live,” Lundquist said. “There have been storms like this in the high terrain, which is why Mission Creek in Kelowna has peaked out a couple of times in the last month or so.

“But we haven’t seen something like that this year and it seems as though it affected people in Penticton the most.”

Before the anticipated heatwave next week — where temperatures are expected to reach up to 32 C — Lundquist says that people in the Okanagan should still be on guard for severe storms until Thursday.

“We’re not out of the woods just yet,” he said. “‘There’s another storm that may be coming on Thursday, and we’re worried about that, too.”

Environment Canada weatherNewsOkanagan

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Rain event, transit masking, STC wellness centre highlight Saskatoon city council |

Rain event, transit masking, STC wellness centre highlight Saskatoon city council  |

The response to last week’s rain event was a big topic at Saskatoon city council Monday afternoon.

“In the 24 hours from the beginning of the storm over 1,200 calls were recieved at the customer care centre, with 114 that required service,” said Angela Gardiner, general manager with Utilities and Environment.

Mayor Charlie Clarke said a lot of credit should be given to the city for the rain event response,

“It’s a moment worth celebrating for the city to be able to do that and I think lots of people I’ve talked to have said good on the city for that” said Mayor Clarke.

Councillor Bev Dubois put forward a motion seconded by councillor Donauer for an investigative device that could signal to drivers not to proceed under overpasses when water or snow gets to a dangerous depth.

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Councillor Loewen put forward a motion also seconded by councillor Donauer to receive information back and to be transparent about what is learned about our infrastructure.

The motions carried unanimously.

Read more:

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Masking on city transit was another topic of discussion.

Saskatoon Fire delivered the June COVID-19 update, with the motion of the information be received being moved by councillor Jeffries and seconded by councillor Gersher.

The update recommended masking continue to be mandatory on transit on a month-to-month basis.

Councillor David Kirton motioned to make masks optional, and council agreed.

Councillors Gough, Loewen, and Gersher were the only one to oppose the move.

Council plans to re-visit mandatory masking on transit in the fall.

The STC Wellness Centre’s temporary location also stirred up a lot of talk at council.

Council looked at several different options for the STC to have outdoor space and decided moved a motion to use the sidewalk in front of the building.

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The option is temporary and will be revisited at the end of October.

Read more:

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Council also brought up the residential speed limit review program, a program proposed by councillor Kirton several months ago.

The program would entail volunteers working with police to track speeders.

Council passed the motion, sending it to the Board of Police Comissioners for more information.

The board will report back with more information at a later date.

© 2022 Global News, a division of Corus Entertainment Inc.

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Rain! Calgary takes steps to prep for a major weather event – LiveWire Calgary

Rain! Calgary takes steps to prep for a major weather event - LiveWire Calgary
Higher steel gates have been placed along the Glenmore Dam. This mitigates the effect of smaller scale floods, allowing resources to be diverted to more vulnerable areas, ETHAN WARD/ FOR LIVEWIRE CALGARY

Calgary is forecasted to get a lot of rain over the next few days, and that’s raised the flood alert in the city.

The City issued a boating advisory for the Elbow River due to higher-than-expected flow rates. Calgarians are asked to stay off river during this time.

But before we get too far, it’s important to put things in perspective. The forecast – as it stands – calls for between 75 to 100 millimetres of rain over the next few days.

That’s roughly half the 220 millimetres averaged during the 2013 flood, according to Francois Bouchart, director of Water Services with the City of Calgary.

Still, he said the forecasts have changed continuously since the middle of last week.

“We knew there was an event coming, the event was identified as being much smaller,” he said.

“Now, as we get closer to the events materializing, we’re working very closely with the province and Environment Canada and we’re now at a point where this is a significant enough event that we’ve taken specific steps to prepare for the event.”

Water levels have been dropped in the Glenmore Reservoir in preparation. It will be 3.5 metres below crest to prepare for the additional water.  Bouchart said they also have an agreement with TransAlta for the Ghost Reservoir further upstream to draw it down. He said it’s been drawn down lower than the expected amount.

Pathways in lower-lying areas are being closed. The City is also stockpiling materials to provide riverbank protection and temporary barriers. Protective balls are also being deployed so rising water can’t push back into the stormwater system.

The next 24 to 48 hours

The first layer of defense is the forecasts, said Bouchart. As they receive Environment Canada information, they’re able to extrapolate potential flow rates upstream. They work with the province to confirm that the data and the forecasts are telling the same story.

“That allows us to understand what flow rates we can anticipate, when we can anticipate the peak occurring. And that allows us to start looking at what are the triggers at different points,” Bouchart said.

Even though the risk appears to be smaller, Bouchart said they’re taking things very seriously.

“There’s always a risk. We can never eliminate the risk,” he said.

He said flood investments made over the past nine years have significantly improved the protection of lower-lying areas. At this point, Bouchart said they don’t anticipate it being put to the test.

“I want to caution people that the models are still predictions. The weather is so dynamic that we will just continue monitoring, forecasting and responding as it evolves,” he said.

The City is asking residents in lower-lying areas to take precautions.

  • Move valuables and documents out of your basement as basement seepage is possible in river communities in lower-lying areas.
  • If you have a sump pump or backflow valve, ensure it’s working.
  • Direct rainwater away from your home: Eavestroughs and extensions should drain at least 1.5 metres (5 feet) away from your and your neighbour’s home and onto a landscaped area so the water can soak into the ground.

They also want Calgarians to be cautious around the rivers. While they don’t expect the banks to be breached, the flows will be higher and it’s dangerous.

The water can also lead to pooling on streets. If a storm drain is unable to clear within 90 minutes, take a photo and send it to Calgary 311.

Monitor flow rates here:

More Calgary flood info here.

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Rain or shine, there’s plenty to do around Lethbridge this weekend

Rain or shine, there’s plenty to do around Lethbridge this weekend

Lots to do in Lethbridge this May long weekend, May 20, 2022 (Photo: LNN)

By Drew Stremick

May 20, 2022 | 6:31 PM

LETHBRIDGE, AB — As we head into the long weekend there are a handful of events happening around Lethbridge that are sure to keep everyone in your household entertained.

Parents looking for a free family event this weekend can check out Saturday Matter Day on, you guessed it, Saturday, May, 21, 2022. This is a free event put on by Rise Above Mental Health and Community Supports, and will be happening from 12 p.m. until 4 p.m. in the Latter Day Saints Church Gym at 2213 6A Avenue N.

For anyone who wants to avoide any potential bad May Long weekend weather, but want to hang out and have a drink with friends, check out “Anything Goes!” at Didi’s Playhaus located at #210 517a 4 Avenue S. You can enjoy playing board games, a library of musicals for viewing, or music and drinks. The fun starts at 7 p.m. on Saturday May, 21, 2022. Tickets are only available at the door.

If you would rather watch some superpowered performances, Circus Funtastic is putting on three performances of its Superhero Adventure. All three shows take place at the Exhibition Park South Pavilion, located at 3401 Parkside Drive South on Saturday May, 21, 2022. Audiences can expect to see acrobats, jugglers, clowns, and a real-life transformer. Tickets are available on Eventbrite.

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Learn how to conserve rain water in new online event by eMERGE

Learn how to conserve rain water in new online event by eMERGE

eMERGE says the reduction in your monthly water consumption and benefits to the environment can be well worth it

With spring showers approaching, a local environmental organization wants to teach residents how conserve the water.

eMERGE is inviting residents to register for an online event called Rain Water Harvesting: From summer rain barrels to 4 season system.

The online event takes place on Thursday, March 24 at 7 p.m. To register, click here.

A release from eMERGE says participants will learn how they can buy a rain barrel from the City of Guelph and access rebates up to $2,000 for whole home rain water harvesting systems.

While a daunting topic, the release said the reduction in your monthly water consumption and benefits to the environment can be well worth it.

The event will also discuss how residents can get a rebate for providing proof of reduced water consumption to the City of Guelph program, Blue Built Home.

This is a pay-what-you-can event. Tickets for this event are $5, but residents can also make a donation instead. 


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Minnesota seeing more big rain events, less extreme cold

Minnesota seeing more big rain events, less extreme cold

RENVILLE, Minn. — Starting Wednesday afternoon and continuing into the night, the rains fell.
One day later, the August 11, 2016 headline in the West Central Tribune summed up the flooding that resulted throughout much of Willmar as a “1,000 year event.”

Expect more of them.

Pete Boulay, climatologist with the Minnesota Department of Natural Resources, said we are seeing an increasing frequency of mega-rainfall events.

Boulay, and Todd Peterson, of the Sand County Foundation in Des Moines, Iowa, were featured speakers at the Hawk Creek Watershed Project’s annual meeting on March 9 in Renville.

Boulay said the state has been seeing temperatures rise by an average of one-half degree each decade.

Despite last year’s drought, Boulay said our weather has otherwise been trending wetter and warmer. The change is most pronounced since the 1970s. Our weather in the 1950s and 1960s was more benign or consistent, he said.

While variability and big swings remain the Minnesota norm, there are obvious trends based on more than 100 years of weather data.

During the winter, we are seeing fewer cold extremes. He pointed to the records kept by the Opjorden family at their home outside of Milan since 1897. Luther Opjorden, who continues the practice his grandfather started, records fewer days with low temperatures of minus-30 or minus-40 degree temperatures compared to his father or grandfather.

That might seem like a good thing, but Peterson and Boulay both noted that those bitter cold days are beneficial to agriculture and forestry in the state. They help keep in check a wide variety of pests, especially invasives like the Emerald Ash Borer.

We experienced some of our wettest years from 2010-2019. Areas in the Hawk Creek watershed recorded a “surplus” of moisture over the norm ranging from 30 to 50 inches during this time frame.

Our recent drought began showing itself in late 2020, but a surplus of moisture in the ground helped carry crops through the season. The drought we experienced from late 2020 and through 2021 until fall was the worst since 1987-89, according to Boulay. One of the worst droughts ever was the “one hit wonder” in 1976, which was followed by the 1987-89, 2012 and 2021 droughts.

Moisture levels in western Minnesota are recovering. Soil moisture and stream flows are back to normal, although lake levels have not yet fully rebounded from the 2021 drought, according to Boulay. Parts of eastern Minnesota are still drier than the norm. He also pointed out that to the west into South Dakota, the drought conditions continue.

Peterson, with the Sand County Foundation, said the changing climate adds to the urgency needed to adopt farming practices that reduce erosion and benefit soil health. He said we continue to lose our topsoil at 23 times the rate that soil can be formed by natural processes. Mega-rain events and other trends exacerbate the soil losses. In Iowa, the rate of topsoil loss has actually increased.

In the last 40 years, we have been losing an average of five tons of topsoil per acre per year on cultivated ground. That amounts to the thickness of a dime per year. Stack 40 dimes on top of one another and the loss is put into perspective. “We’ve lost half of our topsoil, folks,” said Peterson.

The Sand County Foundation was founded by conservationist Aldo Leopold, and focuses on working with the owners of private lands. Roughly 50 percent of the land in the U.S. is private and 70 percent of that is in agricultural use, he pointed out.

Three-fourths of the sediment the Mississippi River carries as its leaves Minnesota for the Gulf of Mexico comes from the Minnesota River basin, he said.


Big rainfall events like this August 10-11, 2016 event in Willmar are increasing in frequency, according to state climatologist Pete Boulay. The former S & F Furniture store in Willmar was among the local businesses that had to deal with flood waters from the rain event. Boulay spoke at the Hawk Creek Watershed Project annual meeting on March 9.

Tom Cherveny / West Central Tribune file photo