2018 United States–Canada tornado outbreak
Major damage to apartment buildings in Gatineau, Quebec, as a result of an EF3 tornado
|Formed||September 20, 2018; EDT|
|Dissipated||September 21, 2018|
|Max. rating1||EF3 tornado|
|Casualties||1 fatality (non-tornadic), 31 injuries|
|Areas affected||Ohio, Iowa, Minnesota, Wisconsin, eastern Ontario, and southern Quebec|
|1Most severe tornado damage; see Enhanced Fujita scale|
The 2018 United States–Canada tornado outbreak was a two-day tornado outbreak that affected the Great Lakes region of the United States on September 20, 2018, and the National Capital Region of Canada on September 21, 2018. 37 tornadoes were confirmed, including a long-tracked EF3 that moved along a 80 km (50 mi) path from near Dunrobin, Ontario to Gatineau, Quebec, and an EF2 in the Nepean sector of Ottawa. The tornadoes in Ottawa-Gatineau were declared one of the ten most significant weather events of 2018 in Canada by the Meteorological Service of Canada.
Numerous tornadoes touched down in Minnesota on the initial day of the outbreak, including a high-end EF2 that caused major damage in Morristown, Minnesota. Other damage occurred in Eastern Ontario due to downburst winds from the severe thunderstorms. One death was reported as a result of straight-line winds that occurred during the outbreak, and 31 people were injured.
In the Great Lakes region of the United States, a warm front surged in a hot, unstable air mass ahead of a strong cold front on September 20. An enhanced risk of severe weather was issued by the Storm Prediction Center (SPC), including a 10% hatched risk area for tornadoes stretching from southern Minnesota into Wisconsin. Later that evening, a quasi-linear convective system with numerous embedded circulations and bowing line segments produced many tornadoes across southern Minnesota. This included a high-end EF2 that heavily damaged or destroyed many homes in the town of Morristown, Minnesota. Another EF2 tornado damaged the local airport in Faribault. A few tornadoes were also confirmed in Iowa, Wisconsin, and Ohio, and damaging winds from the line of storms also caused significant damage. Embedded downbursts produced destructive straight-line winds of up to 100 mph (160 km/h) during the event. With 25 tornadoes in a matter of hours, this event was Minnesota's third most prolific tornado day on record.
The severe weather threat was expected to move eastward to affect southern Ontario and a part of southwestern Quebec the next day. On September 21, a significant severe weather threat was confirmed across southern Ontario and the Outaouais region of Quebec, with the potential for severe thunderstorms and tornadoes noted.
Severe thunderstorm watches and warnings along with wind warnings and special weather statements were issued across the parts of Ontario as early as the pre-dawn hours of September 21, which remained in effect until that evening. The warm humid air mass reached Ontario that morning of September 21, along with localized thunderstorms with heavy torrential downpours in most of the areas across southern Ontario and again later that day during the tornado outbreak. Record breaking temperatures across southern Ontario ranged from the high 20s into the low 30s.   Tornado watches and warnings were issued by that afternoon.
On the afternoon of September 21, 2018, a localized outbreak of tornadoes impacted eastern Ontario and southern Quebec. During the event, Environment Canada issued numerous tornado warnings as multiple discrete tornadic supercells moved through the area. Between 3:30 p.m. and 6:30 p.m. EDT, seven tornadoes, six of which were strong, caused considerable damage in and around the National Capital Region of Canada.
The most significant tornado of the event made a direct strike on the small community of Dunrobin in the west end of Ottawa, then crossed the Ottawa River and struck the Mont-Bleu residential area in the Hull sector of Gatineau, Quebec. The Dunrobin-Gatineau tornado was classified as a high-end, long-tracked EF3, with peak winds reaching 265 km/h (165 mph). Approximately 25 people were injured by the EF3 tornado, six of those taken to the hospital and five people had life-threatening injuries. At least 200 buildings were damaged and an unknown number were destroyed along the path. During the event, the long-tracked EF3 tornado that struck Dunrobin and Gatineau was visible on the horizon behind the Parliament Hill buildings in Ottawa. A still image of the funnel was also captured from a live webcam.
A second damaging tornado, rated EF2, caused significant damage in the Arlington Woods, Craig Henry, and Merivale Road residential areas of Nepean, with peak winds of 220 km/h (140 mph) The tornadoes were preceded by severe thunderstorms throughout Ontario and Quebec. Five other tornadoes also caused minor to moderate damage in the region, though they remained over remote forested areas and mostly damaged trees and power lines. A single EF1 tornado also occurred in Iowa during the early morning hours of September 21. The severe weather threat then diminished by late Friday evening, with cool windy conditions. 
Damage from the tornadoes caused more than 272,000 customers of the National Capital Region to lose power, with some of the outages lasting for days. In addition to the tornadoes, microbursts and hail from the severe thunderstorms also caused considerable damage across Ontario and Quebec. 
Most of the severely damaged buildings that remained intact after the tornado were under repair. The Dunrobin Plaza shopping center, which was severely damaged by the tornado, was demolished in December 2018, more than two months after the tornado.   In October 2018, a month after the storm, it was announced that the September 21 tornadoes caused a massive $295 million in insurance costs, making it one of 2018's costliest storms in Ontario.    
The Dunrobin-Gatineau EF3 was the strongest tornado to hit eastern Ontario since 1902.   The last time an EF3 tornado occurred in Ontario prior to this event was the Goderich tornado in August 2011. One non-tornadic death occurred as a result of this severe weather outbreak. The fatality was reported in the township of Rideau Lakes, Ontario, after a man was struck by a falling tree after being caught in straight-line winds.
The National Capital Region power outages
One of the sites that was affected by the Arlington Woods EF2 tornado was the Merivale electrical substation, one of the two major stations in the city, located near the intersection of Merivale and Hunt Club Road in western Ottawa. While there is no proof confirming whether or not the tornado directly struck the station, it did rip off the roof of two nearby buildings, slamming into the infrastructure, insulators, and wires. Furthermore, the effects of the storm snapped approximately 80 to 90 Hydro poles in the area, downing many others, and leaving pole and wires dangling.
This was the main reason for the longest power outages in the Ottawa-Gatineau region, affecting more than 300,000 customers of the 331,777 total customers who use Hydro Ottawa, plus those served on the Quebec side by Hydro-Québec. Rebuilding the power plant was especially difficult, which took Hydro One and Hydro Ottawa two days working to repair enough of the damage to restore power. Finally, on the evening of September 22, power was restored in some neighbourhoods in southwestern Ottawa. Repair of the downed poles was done as fast as possible, as to restore heat and power as well in several residences.
Although electricity had been restored, the power plant had still required additional repairs, and Hydro One continued working on critical repairs to the station in order to return it to its full potential state. Planned power outages around the city affected more than 50,000 Hydro One and Hydro Ottawa customers to replace important elements. Work at the Merivale station was expected to last for several months.
September 20 event
September 21 event
- CONFIRMED: Two tornadoes, one downburst hit Ottawa region, The Weather Network, September 22, 2018
- Dave Phillips of the Meteorological Service of Canada (December 2, 2018). "Ottawa-Gatineau tornadoes on summer's last day". Canada’s top 10 weather stories of 2018. ECCC. Retrieved December 24, 2018.
- Storm Prediction Center (September 20, 2018). "Sep 20, 2018 0600 UTC Day 1 Convective Outlook". National Weather Service. Retrieved November 20, 2018.
- US Weather Forecast Office in Twin Cities, MN (November 15, 2018). "September 20, 2018 Tornado Outbreak and Widespread Damaging Wind (updated 11/15)". National Weather Service. Retrieved November 20, 2018.
- US Weather Forecast Office in Cleveland, OH (November 15, 2018). "Two Tornadoes near Middlefield, OH Sept. 20, 2018". National Weather Service. Retrieved November 20, 2018.
- Storm Prediction Center (September 20, 2018). "Sep 20, 2018 0600 UTC Day 2 Convective Outlook". National Weather Service. Retrieved November 20, 2018.
- "Elevated Severe Thunderstorm Risk With Damaging Winds, Lightning, Hail and Possibly an Isolated Tornado Risk (Fri, Sept 21st, 2018)". InstantWeather. September 21, 2018. Retrieved November 20, 2018.
- Wind gusted to 83 km/h in the Sault, yesterday: Environment Canada. Also confirms tornado in Ottawa area and high temperature records broken in areas of southern Ontario, sootoday.com, September 22, 2018
- Ottawa International Airport, ON weather historical data for September 21, 2018, Wunderground, September 21, 2018
- Tornado warning issued for Ottawa-Gatineau area, CBC News, September 21, 2018
- "Tornado aftermath: The science behind the twisters". The Ottawa Citizen. 2018-09-23. Retrieved 2018-09-24.
- "Tornado hits Ottawa-Gatineau area, damaging buildings and flipping cars | CTV News". Retrieved 2018-09-22.
- "Updated: 'It's devastating': Tornado levels houses, leaves trail of destruction". 22 September 2018.
- "Tornado tears through Ottawa and Gatineau area, causing injuries | The Star". thestar.com. Retrieved 2018-09-22.
- "Dash cam of tornado and the damage in Dunrobin. The Dunrobin businesses was devastated, but the driver was unharmed". CBC News. September 2018.
- The sky does not look good, Twitter, September 21, 2018
- Live shot of Parliament Hill downtown Ottawa right now. Tornado warned storm cell tracking north of downtown towards Gatineau, Kelly Sonnenburg TWN/trendsmap.com, September 21, 2018
- "Tornado destroys homes, hydro poles in Hunt Club and Greenbank area". CBC News. September 21, 2018.
- Inc., Pelmorex Weather Networks. "'Dynamic fall storm' slams Quebec with severe weather". The Weather Network. Retrieved 2018-09-22.
- "At least 2 tornadoes touch down near Ottawa; about 272,000 without power in Ontario and Quebec". Global News. Retrieved 2018-09-22.
- Here's how the Ottawa-Gatineau tornadoes formed so quickly, Global News, September 24, 2018
- Tornado strikes were 'luck of the draw,' says meteorologist, CBC News, September 23, 2018
- "6 tornadoes hit Ottawa-Gatineau region, Environment Canada says". CBC News. Retrieved 2018-09-26.
- Map of where the six tornadoes touched down in Ottawa-Gatineau areas on September 21, 2018, CBC News, September 25, 2018
- UPDATE: Officials increase Friday's tornado count to SIX, The Weather Network, September 26, 2018
- Ontario: Cool down follows damaging wind storm, The Weather Network, September 21, 2018
- "Here's where power is out across the region - CBC News".
- Kalvapalle, Rahul. "Ottawa residents could be without power for days after tornado devastates Hydro One station". Global News. Retrieved 2018-09-22.
- Chianello, Joanne. "When is the power coming on? Not for days". CBC News. Retrieved 22 September 2018.
- Third tornado at Calabogie and White Lake is confirmed by Environment Canada, Ottawa Citizen, September 24, 2018
- Environment Canada confirms 3rd tornado hit Calabogie, White Lake, insideottawavalley.com/Renfrew Mercury, September 25, 2018
- The Destructive Dunrobin - Gatineau Tornado. Includes images and videos of the tornadoes and damage
- Dunrobin Plaza demolition underway, CTV Ottawa, December 6, 2018
- Demolition begins at Dunrobin Plaza, but future still unclear, CBC Ottawa, December 9, 2018
- Tornado damage costs insurers $295M, Ottawa Citizen, October 23, 2018
- Ottawa-Gatineau tornadoes cause nearly $300 million in insured damage, insurancebusinessmag.com, October 23, 2018
- Were the Ottawa-Gatineau tornadoes the costliest in Canadian history?, canadianunderwriter.ca, October 17, 2018
- Cellphone video of Ottawa-Gatineau tornado, CBC News, September 2018
- Dunrobin tornado strongest to hit eastern Ontario since 1902, 580 CFRA, October 5, 2018
- Ottawa newsmakers 2018: Sept. 21 tornadoes left us battered, the biggest blow since 1903, Ottawa Citizen, Originally published December 27, 2018; Updated January 1, 2019
- "Inside Hydro One's tricky problem: How to turn on the lights with a major power station down". Ottawa Citizen. 2018-09-24. Retrieved 2018-11-15.
- "Tornado aftermath: 'The roof fell on us' — Twisters leave residents awestruck and in the dark". Ottawa Citizen. 2018-09-23. Retrieved 2018-11-15.
- Limited, Hydro Ottawa. "About Us - Governance - Overview - Hydro Ottawa". hydroottawa.com. Retrieved 2018-11-15.
- "Inside Hydro One's tricky problem: How to turn on the lights with a major power station down". Ottawa Citizen. 2018-09-24. Retrieved 2018-11-15.
- Limited, Hydro Ottawa. "Media - News Releases - Hydro Ottawa". hydroottawa.com. Retrieved 2018-11-15.
- Ottawa airport forced to use backup power as storm sweeps through region, Global News, September 21, 2018
- Clean-up begins after storm hits Ottawa-Gatineau, CTV Ottawa/CTV Morning Live, September 22, 2018
- NWS Damage Survey for September 20th 2018 Multiple Tornadoes Near Middlefield Ohio (Report). Iowa Environmental Mesonet. National Weather Service Weather Forecast Office in Cleveland, Ohio. September 21, 2018. Retrieved September 22, 2018.
- NWS Damage Survey for 09/21/2018 Tornado Event (Report). Iowa Environmental Mesonet. National Weather Service Weather Forecast Office in Davenport, Iowa. September 24, 2018. Retrieved September 24, 2018.
- NWS Damage Survey for Superior Iowa Tornado - Update 2 (Report). Iowa Environmental Mesonet. National Weather Service Weather Forecast Office in Sioux Falls, South Dakota. September 24, 2018. Retrieved September 24, 2018.
- NWS Damage Survey for 09/20/2018 Tornado Event - Update 2 (Report). Iowa Environmental Mesonet. National Weather Service Weather Forecast Office Twin Cities, Minnesota. September 28, 2018. Retrieved September 28, 2018.
- NWS Damage Survey for 09/20/18 Tornado Event - Initial Issuance (Report). Iowa Environmental Mesonet. National Weather Service Weather Forecast Office Twin Cities, Minnesota. September 22, 2018. Retrieved September 22, 2018.
- "7 Tornado Outbreak in Eastern Ontario/Southern Quebec".
- "In Arlington Woods, tornado cleanup begins amid 'ripped apart' buildings - CBC News".
- "Egan: Crushed by tornado's fury, Renfrew man may never walk normally again". 5 November 2018.
- "Egan: Overlooked in Calabogie — the F1 tornado that escaped limelight". 25 September 2018.
- "Environment Canada confirms 3rd tornado hit Calabogie, White Lake". 25 September 2018.
- "Environment Canada Investigates Possible Tornado in Sharbot Lake". iHeartRadio.
- "6 tornadoes hit Ottawa-Gatineau region, Environment Canada says". CBC News. 25 September 2018.