Just as record-level floodwaters that forced mass evacuations begin to recede in Western Washington stateResidents in the Pacific Northwest are bracing for another severe weather system that will likely cause rivers to swell to dangerous levels again.
An unusually powerful system known as an atmospheric river hit the region earlier this week. more than a foot of rain and river floods that stretch across the state towards Canada to dangerous levels. Incessant rain caused landslides to sweep through populated areas, washing away houses and forcing families to sit on rooftops waiting for help.
Bouts of heavy rain caused flooding outside Washington that spread into British Columbia, where mudslides and flooding forced more people to evacuate and closed several major highways into Vancouver.
Although atmospheric rivers are not uncommon in the Pacific Northwest at this time of year, these paired systems unusually powerful and cause cross-border problems in the US and Canada.
What are atmospheric rivers and why are they getting worse?
Because water flows through rivers on land, atmospheric rivers are large channels in the atmosphere that transport water vapor from the tropics and are essential to the world's annual water supply. In the Pacific Northwest, atmospheric rivers typically occur in the fall and winter, bringing water-laden air from areas around Hawaii to the West Coast.
Meteorologists say the severity of this particular weather event is due in part to humidity. even further in the western Pacific Ocean near the Philippines.
In the best cases, these systems can bring much-needed rain to drought-prone areas, according to the USDA. In extreme cases, such as the recent flooding over Washington and Oregon, heavy rain from these atmospheric rivers can bring devastating floods and landslides.
While much of the American public is focused on swollen rivers and flood damage in western Washington, neighbors to the north in British Columbia, Canada, are facing their own challenges.
Some experts believe the US should take action to prevent potential flooding across the border.
Can Canada count on the US to upgrade its infrastructure to stop transboundary flooding?
As Washington's Nooksack River flooded this week, sending a surge of water north across the border into British Columbia, some Canadians were haunted by memories of the flood which has devastated the neighboring community in 2021.
Four years ago, when the Nooksack River burst its banks, pushing large amounts of water north into the Sumas Prairie in Abbotsford, British Columbia, it triggered record flooding that forced evacuations, closed major highways and caused more than a billion dollars in damage. Canadian press reports.
Although the Nooksack River does not cross the Canadian border, during floods the river's water does flow into areas near the border, creating a significant flood risk for Canada. According to the Globe and Mail report in 2021Canadian politicians and engineers have called on Washington state government officials to invest in flood mitigation infrastructure on the Nooksack River to address potential threats.
Canadian flood risk researcher Charlotte Milne told CBC A report released Friday said the United States has been slow to take action to address transboundary flooding.
While Milne acknowledged that some U.S. initiatives have begun to address the watershed issue, including the Snohomish Watershed Resiliency Action Plan and the Nooksack-Sumas Transboundary Flood Initiative, she argued that they should have started earlier.
“It's not that people don't think about these things. They do take time. But I think they could happen a little faster,” Milne told CBC.
Nooksack and Sumas rivers. reached record levels again during this week's storms. As of Friday evening, 500 properties were registered. under evacuation orders in Abbotsford, and only one flood warning remained in effect for the area near a section of the Sumas River in British Columbia.
Researchers have found that the man-made climate crisis has contributed to worsening weather events, including atmospheric rivers. According to research conducted by the US Geological Survey, scientists observed a pattern of increasing water vapor transport to the West Coast over the past 70 years, which they attribute to warming of the ocean surface.
Meteorologists in Washington estimated that this week's weather system brought more than 5 trillion gallons of rain to the state over seven days, the Associated Press reported. reported.
Speaking to the press this week, Washington Gov. Bob Ferguson emphasized the severity of recent weather conditions.
“The flood levels we're seeing are potentially historic,” Ferguson said during a news conference Thursday. “I just want to emphasize how serious the situation is.”
