May 2022 Canadian derecho explained

May 2022 Canadian derecho
Date:May 21, 2022
Wind:89
Windloc:Magog, Quebec, Canada
Windest:118
Windestloc:Ottawa, Canada
Windestref:[1]
Image Location:Canadianderecho2022.jpg
Areas:Southern Ontario, southern Quebec
Duration:9 hours
Track:620
Tornadoes:4
Fatalities:12
Fatalref:[2]
Casualties:12+
Fscale:CEF2
Ef:yes
Damagetype:Widespread damage to residential and commercial property and public utility infrastructure
Damage:C$ 875 million ($780 million USD)

The May 2022 Canadian derecho was a high-impact derecho[3] event that affected the Quebec City-Windsor Corridor, Canada's most densely populated region, on May 21, 2022. Described by meteorologists as a historic derecho and one of the most impactful thunderstorms in Canadian history,[4] winds up to as well as around four tornadoes caused widespread and extensive damage along a path that extended for .

Three cities across southern Ontario declared a state of emergency. At least twelve people were killed, mostly by falling trees.[5] Power outages affected an estimated 1.1 million customers, and thousands were still without power a week after the storm.[6] Hydro Ottawa described the damage dealt to its power distribution system as more severe than the 1998 ice storm. The storm was the sixth-costliest event in Canadian history.[7]

According to an estimate published on June 15 by the firm Catastrophe Indices and Quantification (CatIQ), the insured damage would amount to C$875 million, that is, C$720 million in Ontario and C$155 million in Quebec. This ranks the derecho as the sixth-costliest natural disaster in Canada in terms of insurance claims.[8]

Background

Derechos affecting this region typically develop in the U.S. Midwest and affect only a small part of the Quebec City-Windsor Corridor.[9] This was the first deadly event of this magnitude in Canada since 1999.[10] In Southern Ontario, frequency of a derechos on average once every year in the extreme southwest (Windsor, parts of Essex County), to about once in every four years further north into central areas of Southern Ontario (Barrie, Peterborough, Kingston) and in Northwestern Ontario along a narrow strip of the Minnesota international border. The historic range has likely shifted northward, due to climate change[9]

Typically, derechos anywhere in this area can form from late spring through the summer months. These derechos usually occur when a hot and muggy air mass covers the Midwest and Ohio Valley, the stronger derechos in this region tend to develop on the northern boundary between the hot, humid air and cooler, drier air where there is also an elevated mixed layer (EML).[11] [9]

Most derechos in Canada are progressive derechos which skirt the northern edge of a heat wave high pressure area, or hybrid derechos which are similar to progressive derechos, but arise ahead of a cold front.[12] Tornadoes which accompany these types of derechos are usually Quasi-Linear Convective System (QLCS) tornadoes which are embedded in the bow echo.[12] [13]

Meteorological history

A persistent May heat wave in the U.S. expanded sporadically to include southern Ontario and Quebec throughout May, resulting in unseasonably warm temperatures more typical of July.[14] After a brief respite, the heat returned on May 19, 20, and 21.[15] At 11 am, Toronto Pearson Airport hit 29.3C, three degrees shy of the record for that date, with a humidex of 36C.[16] Ottawa-Gatineau hit 31.5C at 2 pm, one degree shy of the record for that date, with a humidex of 38C.[17] A sharp cold front was expected to bring thunderstorms through the region on Saturday, prior to a precipitous drop in temperature potentially resulting in subsequent frost.[18] [19] [20]

The system first formed south of Chicago.[21] On Saturday morning at 10:37 am EST, thunderstorms with significant wind developed in Macomb and St. Clair counties in Michigan. The wind of these storms snapped some trees, mostly in St. Clair County, but this cluster of thunderstorms had not yet formed a bow echo.[22]

The derecho developed near Sarnia at 9:30 am. By 10:45 am when the storms hit London, the derecho had coalesced into a bow front roughly wide[23] and had developed wind speeds of close to . The bow front continued to widen and intensify east of London, roughly following a corridor between Highway 401 and Highway 7 in Ontario, and then along the Autoroute 20 in Quebec.

The storm moved east at an average 100 km/h, striking Toronto at 1:00 pm, Ottawa at 3:50 pm, Montreal at 5:30 pm, and Quebec City at 6:30 pm.[24] [23] The weather changed very rapidly as the derecho approached. At Pearson International Airport, in the period between 12:52 pm and 1 pm, gust wind speeds went from 72 km/h to 120 km/h.[25]

The bow echo retained its structure for nine hours, and covered a total track length of . It weakened over south-central Quebec, and dissipated in the Atlantic Canada region by early Sunday morning.

Straight line wind speeds

The highest reported wind gust of was recorded at Lake Memphremagog, Quebec.[26] In Ontario, Kitchener/Waterloo Airport recorded a peak wind gust of .[27] [28] [29] Most of the weather stations along the derecho's path recorded wind gusts near or above, including the Greater Toronto Area, Ottawa, Trois-Rivières, and Quebec City.[30]

A storm survey from the Northern Tornadoes Project reported a severe downburst in parts of southern Ottawa. Its windspeeds reached up to .[24] [31] [32]

A gust of at Pearson International Airport set a May record, and is the fifth strongest wind gust ever recorded at that location.[33]

Tornadoes

An (C)EF2 tornado which was embedded in the leading edge of the derecho[13] struck Uxbridge, Ontario at 1:15 pm.[24] [34] [35] Two (C)EF1 QLCS tornadoes were confirmed in London, Ontario.[36] Another (C)EF2 tornado was detected in the Lake Scugog area .[37]

Prediction

For the first day of the Victoria Day long weekend, atmospheric instability was forecast throughout Michigan's south peninsula, the Ohio Valley, southern Ontario and southern Quebec. Most of southern Ontario south of the 401 was assigned a marginal risk of severe weather. Tornadoes were predicted to be possible in eastern Ontario into southern Quebec in the afternoon.[38]

Environment Canada issued weather statements for Sarnia and Windsor at 9:43 am,[39] which was upgraded for Sarnia to a severe thunderstorm warning at 10:25 am.[40] Severe thunderstorm watches for the London area followed at 10:41 am,[41] upgraded to a severe thunderstorm warning at 11:08.[42] The alert mentioned possible strong wind gusts up to, along with nickel-sized hail.

Severe thunderstorm watches were issued for points eastward of London at 11:19 am.[43] These were later upgraded to severe thunderstorm warnings.

Additionally, after the derecho hit London, Environment Canada issued an emergency alert for regions in Ontario and Quebec along the path of the storm, with alerts going out over cellphones, television, and radio.[44] This was the first time Environment and Climate Change Canada (ECCC) issued an Alert Ready message for a Severe Thunderstorm Warning.[45]

Impact

The derecho impacted roughly 15.6 million people, representing about 41 percent of Canada's population.[46] Strong winds downed over 1,900 hydro poles, five metal transmission towers, and numerous trees along the path of the derecho.[47] [48] [49] [50] The damage included the downing of over 300 power poles in Ottawa.[51] [52] In Quebec, the Laurentides, Lanaudière, and l’Outaouais were most affected.[53]

Eleven people were killed in eastern Ontario by windthrown trees or branches. Another person was killed after their boat sank in the Ottawa River near Gatineau, Quebec.[54] Most of the victims were engaged in recreational activities on the holiday weekend.[55]

Extensive damage was inflicted upon homes and buildings by wind and falling trees,[56] with some homes completely destroyed.[57] The communities of Stittsville, Hunt Club, Navan, and Sarsfield, where a church steeple was toppled and farms were destroyed, were the worst hit in the Ottawa area. The Saint-Fidèle church in Fassett also lost its steeple.[58] In Rockland, a 30-ton silo was moved a foot and had its roof torn off.[59] Power outages affected over 1.1 million customers, with 586,000 Hydro One outages in Ontario and 550,000 Hydro-Québec outages.[60] [61] In Ottawa, the airport and water treatment plant lost grid power for more than 24 hours.[62] In a letter to Ottawa mayor Jim Watson, Hydro Ottawa described the damage dealt to its power distribution system as "beyond comprehension" and more severe than the 2018 tornadoes or the 1998 ice storm.[63]

Rail and air transportation were significantly affected. Trains along the Windsor-Ottawa corridor were delayed by hours due to trees on the tracks, with some passengers having to be bussed to their destinations. Flights were delayed at Pearson International Airport, while a small plane at London International Airport was flipped over despite being strapped down. Subway trains in Toronto were stalled after one train ran over a downed tree.[64]

Aftermath

The storm was the sixth-costliest event in Canadian history.[7] It was also the most damaging storm ever experienced in Hydro Ottawa history, surpassing the January 1998 North American ice storm and the 2018 Ottawa tornadoes.[65]

The municipal governments of Uxbridge and Clarence-Rockland declared local states of emergency on May 21. Peterborough declared a state of emergency on May 25.[66] [67] Ottawa did not declare a state of emergency; mayor Watson stated that the city had enough resources to handle the situation and that declaring a state of emergency would only amount to a symbolic gesture.[68]

Due to the extensive infrastructure damage and large number of fallen trees, at least a quarter of outages in the hardest hit areas continued more than four days.[69] [62] Ottawa Hydro restored power to just over half its customers after one week.[70] Three hundred Ottawa-area customers were still without power at the beginning of June.[71] Some rural and remote Hydro One customers in the Perth, Bancroft, and Tweed areas remained without power for multiple weeks.[72] [73]

Forty percent of Quebec hydro outages continued two days after the storm hit.[74] [75] Five percent of customers lost power for more than a week.[76]

Rogers and Bell reported widespread internet and television service outages in Ottawa and the surrounding area, but did not provide information on when service would return.[77] Outages were also reported across southern Ontario.

Due to the Victoria Day holiday, most schools were able to open normally on Tuesday, although a few remained closed because they were still without power.[69]

The National Capital Commission (NCC) greenbelt lost thousands of trees during the derecho, with every greenbelt sector affected. It was the first time the entire NCC greenbelt was closed. Some trails were still closed as of August 25. Red pine logs resulting from the fallen trees could be salvaged at no cost by the public, requiring only a land access permit.[78]

Provincial election

Advance poll voting for the 2022 Ontario provincial election was disrupted by the power outages and by falling trees, particularly in the London, Kitchener-Waterloo, Brampton, Peterborough, and Ottawa regions. Forty-nine advance polls closed after they lost power or were damaged by falling trees or wires, either temporarily or for the day.[79] Some advance poll locations had to be removed or changed, but all locations retained at least one advance poll per riding.[79] [80] One of the London tornadoes brushed the Stronach Community Recreation Centre, where one of the London—Fanshawe advance polls was based.[81]

Provincial elections in Ontario are computerized, but are designed to be used with paper ballots and contingency ballot boxes, as well as hardcopy backups of the electors list.[82] Many polls lacking power were able to operate with natural light.[83] No votes were lost.[79]

Government assistance

At the federal level, Prime Minister Justin Trudeau offered federal aid to severely affected communities.[74]

Locally, Ottawa and Peterborough opened respite centres, with showers and charging stations.[60] [69] Tweed opened a water filling station at its municipal office. Ottawa and Gatineau also offered emergency food aid.[84]

To assist small business owners who had been severely affected by the derecho, Renfrew County offered relief loans to small businesses at 0% interest, with deferred payments for one year.[85]

See also

External links

Notes and References

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  2. News: Maps for May 21st derecho and all 2022 ground surveys . 22 May 2023 . uwo.ca . Northern Tornadoes Project . 25 November 2022.
  3. News: 2022-05-22 . What is a 'derecho'? Climatologist explains Saturday's powerful storm . 23 May 2022 . CTV News.
  4. News: 25 May 2022 . Deadly derecho affected nearly half of Canada's population, spawned EF2 tornado . AccuWeather . 2022-05-29.
  5. News: 11th person dies from weekend storm, tens of thousands Ontarians still without power . 27 May 2022 . CP24.com . Bell Media . 26 May 2022.
  6. News: Two more tornadoes confirmed in Ontario from destructive derecho . 29 May 2022 . The Weather Network . The Weather Network . 28 May 2022.
  7. News: May 21 storm ranked 6th most expensive natural disaster in Canadian history: IBC . 15 June 2022 .
  8. News: fr . . Plus de 875 millions de dollars de dommages assurés . La Presse . June 15, 2022 . June 15, 2022.
  9. Web site: Understanding a Derecho: What is it? . https://web.archive.org/web/20141222110142/http://www.erh.noaa.gov/rah/newsletter/RAHNewsletter_Mar13.pdf . 2014-12-22 . NOAA . dead.
  10. News: CBC News .
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  12. Web site: Facts About Derechos - Very Damaging Windstorms .
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  14. Web site: 'Just a head-shaker': Unexpected May heat wave blankets Ottawa . 2022-05-16 . . https://web.archive.org/web/20230319211803/https://www.cbc.ca/news/canada/ottawa/hot-weather-may-ottawa-record-breaking-1.6453875 . 2023-03-19 . live .
  15. Web site: At least 11 dead in wake of Michigan tornado, Canada derecho » Yale Climate Connections . 23 May 2022 .
  16. Web site: Hourly Data Report for May 21, 2022 - Climate - Environment and Climate Change Canada . 31 October 2011 .
  17. Web site: Historical Data - Climate - Environment and Climate Change Canada . 31 October 2011 .
  18. Web site: Shorts to coats: A wild forecast for Canada's unofficial start to summer . 18 May 2022 .
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  21. News: Bernstein . Jaela . What's a derecho and why is it so destructive? The science behind this powerful storm . June 18, 2022 . CBC . May 25, 2022.
  22. Web site: Storm Prediction Center 20220521's Storm Reports .
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  24. Web site: Weather Summaries - Environment Canada . 6 August 2013 .
  25. News: Environment Canada confirms EF2 tornado was part of deadly Ontario storm . 24 May 2022 .
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  27. News: 21 May 2022 . Three dead, more than 350,000 without power after powerful storm rips through Ontario . 23 May 2022 . CP24 . en.
  28. News: 22 May 2022 . At least eight dead, thousands without power after storm . 23 May 2022 . CP24.
  29. News: 23 May 2022 . Storm leaves at least 10 people dead, many powerless . 23 May 2022 . CP24 . en.
  30. News: Nearly half of Canada's population hit by derecho, why it was harmful. Pelmorex Weather Networks Inc. www.theweathernetwork.com.
  31. News: Ottawa storm winds reached 190 km/H: Researchers . 25 May 2022 .
  32. Web site: EF2 downburst in Ottawa .
  33. News: Derecho leaves roughly 1,000 km of damage, fatalities in its wake .
  34. News: Tornado confirmed in Ontario after destructive long-weekend storm . 24 May 2022 . The Weather Network . Pelmorex Corp. . 24 May 2022 . Oakville ON.
  35. Web site: Uxbridge ON EF2 tornado .
  36. Web site: Two EF1 tornadoes in London, ON . 2022-05-27 . www.uwo.ca . en.
  37. Web site: 2022-06-27 . May 21 derecho update #1 of 2: one more EF2 tornado . 2022-07-11 . www.uwo.ca . Northern Tornadoes Project . en.
  38. Web site: Storm Prediction Center May 21, 2022 0600 UTC Day 1 Convective Outlook .
  39. 1528010758205886464. ECAlertON147. 09:43 EnvCanada issued #Weather statement #Sarnia #ONStorm. 21 May 2022.
  40. 1528019171824521218. ECAlertON147. 10:25 EnvCanada issued #Thunderstorm warning #Sarnia #ONStorm. Details:. Weather #Radar. 21 May 2022.
  41. 1528023287166541826. ECAlertON137. 10:41 EnvCanada issued #Thunderstorm watch #London #ONStorm. 21 May 2022.
  42. Web site: Alerts for: London - Middlesex - Environment Canada . 16 April 2013 .
  43. 1528032738997149697. ECAlertON118. 11:19 EnvCanada issued #Thunderstorm watch #Ottawa(KanataOrléans) #ONStorm. 21 May 2022.
  44. News: GTA, Southern Ontario feeling effects of severe thunder storm . 24 May 2022 . Global News.
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  47. Web site: Hydro One. www.hydroone.com.
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  49. News: Canada storms: at least eight dead amid trail of destruction . 23 May 2022 . The Guardian . Reuters . 22 May 2022.
  50. Web site: Death toll rises in Canada after derecho leaves widespread destruction . Thomas . Leffler . AccuWeather . 22 May 2022 . 7 May 2024.
  51. 1529945501730324485. hydroottawa. The storm damaged more than 300 poles across Ottawa. By comparison, 80 poles needed replacing after the 2018 tornad…. 26 May 2022.
  52. News: 23 May 2022 . Hydro Ottawa says current outages significantly worse than ice storm, tornadoes . CBC News . CBC/Radio-Canada . 23 May 2022.
  53. News: Orages violents | la province victime d'un… derecho . 24 May 2022 . La Presse.
  54. News: Chung . Christine . 22 May 2022 . At Least Six Dead After Severe Thunderstorms Lash Parts of Canada . The New York Times . 23 May 2022.
  55. Web site: Emergency alerts when severe weather happens can be improved: Guilbeault . 25 May 2022 .
  56. Web site: Weather summary for Ontario and the National Capital Region issued by Environment Canada at 11:35 p.m. EDT Sunday 22 May 2022 . Government of Canada . Environment Canada . 23 May 2022 . https://web.archive.org/web/20220523135448/https://weather.gc.ca/warnings/weathersummaries_e.html . 23 May 2022 . 22 May 2022.
  57. News: Woolf . Marie . 23 May 2022 . Death toll from Saturday's storm hits 10 across Ontario and Quebec . CTV News . Bell Media . Clarence-Rockland, Ontario . 24 May 2022.
  58. Web site: More than 149,000 Quebec homes still without power after violent storm .
  59. Web site: "It was crazy" – broker reacts to derecho and what lies ahead .
  60. News: Bickis . Ian . Rabson . Mia . 22 May 2022 . Cleanup underway after storm leaves at least nine dead, thousands without power . .
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  62. News: Cleanup underway after storm leaves at least nine dead, thousands without power . The Toronto Star . 22 May 2022 .
  63. Web site: Storm damage 'simply beyond comprehension,' says Hydro Ottawa . 2022-05-23 . . https://web.archive.org/web/20230319211803/https://www.cbc.ca/news/canada/ottawa/hydro-ottawa-restore-power-storm-1.6463100 . 2023-03-19 . live .
  64. News: 'This is unbelievable': Intense thunderstorm rolls through Ontario and Quebec, leaving five dead . . 21 May 2022 .
  65. Web site: Derecho: Our biggest storm yet | Hydro Ottawa .
  66. Web site: Storm Response Update May 22, 2022 . 23 May 2022 .
  67. News: 25 May 2022 . Peterborough declares state of emergency, more than 150,000 still without power after massive storm . 26 May 2022 . CBC News . CBC/Radio-Canada.
  68. News: Jhalli . Anil . 23 May 2022 . State of emergency not needed says Watson . 26 May 2022 . CityNews Ottawa . Rogers Sports & Media.
  69. Web site: Peterborough declares state of emergency, more than 150,000 still without power after massive storm . 2022-05-25 . . https://web.archive.org/web/20230601090516/https://www.cbc.ca/news/canada/toronto/ontario-storm-power-outages-peterborough-1.6465056 . 2023-06-01 . live .
  70. Web site: 'Bulk' of power system will be up and running Friday night, says Hydro Ottawa . 2022-05-26 . . https://web.archive.org/web/20221111012952/https://www.cbc.ca/news/canada/ottawa/derecho-storm-city-hydro-update-thursday-may-26-2022-1.6466611 . 2022-11-11 . live .
  71. Web site: May 21 storm knocked out power for thousands . 2022-06-02 . . https://web.archive.org/web/20230411010532/https://www.cbc.ca/news/canada/ottawa/power-outage-ottawa-duration-storm-1.6471982 . 2023-04-11 . live .
  72. Web site: Hydro One .
  73. Web site: Some rural eastern Ontario residents could still be without power for weeks . 2022-06-02 . . https://web.archive.org/web/20230416032506/https://www.cbc.ca/news/canada/ottawa/bancroft-tweed-hastings-storm-power-outage-1.6474044 . 2023-04-16 . live .
  74. News: Marchesan . John . Morton . Michelle . 22 May 2022 . Clean-up continues after Ontario storm leaves 10 dead, thousands without power . .
  75. Web site: Challenging storm cleanup still far from over southwest of Ottawa . 2022-06-06 . . https://web.archive.org/web/20230319211803/https://www.cbc.ca/news/canada/ottawa/cloyne-bon-echo-storm-derecho-damage-cleanup-1.6478431 . 2023-03-19 . live .
  76. Web site: A look at the outages caused by the May 21 derecho .
  77. News: Tunney . Joseph . 26 May 2022 . Internet outages after storm frustrate residents in eastern Ontario . 26 May 2022 . CBC News.
  78. News: Lovers of NCC woodlands, frustrated by storm cleanup, worry about Greenbelt's future.
  79. News: Ontario's chief election officer says storm or no storm, the vote goes on . Ottawa Citizen. June 2, 2022.
  80. News: If voting's on your to-do list, here's how to check if the storm has closed your local voting site .
  81. Web site: Two EF1 tornadoes in London, ON .
  82. Web site: Elections Ontario working with hydro companies to restore power to polling stations .
  83. Web site: Ways to Vote .
  84. News: 22 May 2022 . What you need to know about storm cleanup and where to get help . .
  85. Web site: Facebook. Facebook.