Premature classification of atmospheric rivers, according to Environment Canada, months after the wish of British Columbia


“We’re not going to increase the accuracy of the forecast model, but it can help better communicate the impact of the storm, and maybe give an early warning to operational forecasts.” — Ruping Mo, Senior Researcher and Operational Forecaster at Environment Canada

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When torrential rains caused widespread flooding and washed out major highways in British Columbia last fall, the provincial government was quick to signal the creation of an Atmospheric River System Rating System.

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But eight months later, Environment Canada and its scientists say there is still no timetable for when such a system could be operational.

“A decision on whether or not to implement such a scale as an operational information product would be premature at this time,” Environment Canada said in a statement.

Public Safety Minister Mike Farnworth said the province could have a usable rating system for atmospheric rivers early this year.

“It will allow us, I think, to prepare more effectively. From what I’ve been told, I expect it to come. It should be implemented at the beginning of January 2022,” he said during a press conference on November 22.

Over the past few days, some 20 precipitation records had been broken across the province. Landslides closed the Trans-Canada Highway and other key roads, and the Sumas Prairie was flooded as the levees were submerged.

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The rain was brought by an atmospheric river, in which moist tropical air travels long distances in a narrow band. On the west coast of North America, the phenomenon is known as the “pineapple express” because it tends to originate near Hawaii.

The meteorological office said it was studying various rating scales to reflect the intensity of atmospheric rivers with a numerical value, but “there are no immediate plans to officially adopt such a scale operationally in the short term. “.

The British Columbia Ministry of Public Safety did not directly respond to questions about an updated schedule.

But Environment Canada said it focused instead on analyzing the “suitability” of such a system for Canada and noted that any new products must undergo rigorous evaluation and review. peer reviews to ensure its validity and reliability before implementation.

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“It is essential for public safety,” he said in a statement.

Roxanne Vingarzan, senior manager of applied science at Environment Canada, said researchers are aiming for the system to have about five to eight levels, but it’s “very much at the research stage.”

“It is essential that any proposal for a scale or specialized emergency management support product meets the decision-making needs of public authorities. This includes ensuring that situationally relevant information is timely, accurate and well understood,” she said.

One aspect of the study aims to understand how a warming climate will affect the severity and duration of atmospheric rivers, Vingarzan said.

“Climate models indicate that severe storms are expected to become much more frequent in duration and more severe. This is one of the motivating factors behind our project as we expect that these atmospheric rivers will not disappear and, on the contrary, they will have more impact in the future,” she said.

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Ruping Mo, principal researcher and operational forecaster at Environment Canada, said the classification system would be based on the same prediction system that generates current forecasts and warnings. He said current weather models can provide “confident” atmospheric forecast forecasts over rivers up to five days in advance.

“We’re not going to increase the accuracy of the forecast model, but it can help better communicate the impact of the storm, and maybe give an early warning to operational forecasts,” he said. .

Vingarzan added that while a new ranking system would not increase accuracy, it would provide historical context to “identify its rarity and potential impacts”.

“Prediction accuracy depends on weather models that are constantly being improved by the Canadian Center for Meteorological Research (of Environment and Climate Change Canada),” she said in an email.

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In the meantime, Emergency Management BC said the province is ready to use the existing Alert Ready system.

“The Atmospheric River Assessment System is not the only determinant of issuing an alert. If a community or communities sense there is an imminent threat to life or public safety, the province is prepared to utilize the Alert Ready system,” he said in a statement. “First Nations and local authorities are the experts on the ground, and emergency managers – at local and provincial levels – will continue to coordinate closely.

Alert Ready is available across Canada and allows officials to issue public safety alerts through TV and radio broadcasters, as well as wireless devices.

Although the system is coordinated at the provincial level, it is up to local authorities to use it. In extreme cases, the province can step in and issue an alert directly, Farnworth said in May. He noted that while officials were ready to use it in some areas if needed last fall, it is now in place for use across the province.

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