Region With Few AC Units Is Baking Under a 'Heat Dome'

The Pacific Northwest—and Canada, too—must bake for one more day before cooler temperatures arrive on Tuesday, reports the Oregonian. That's a relative term: It's still expected to be unusually hot in Portland, though in the 80s and 90s instead of triple digits. Related coverage of the record-setting heat and worries about what's known as a "heat dome":

• Records fall: Portland hit a record of 108 on Saturday, only to break that mark with a reading of 112 on Sunday, per the National Weather Service. On Monday, the record is expected to tick up to 114.
• New normal? A post at Axios notes that buildings in the Northwest generally aren't built for this kind of heat. Infrastructure in any region is built to accommodate its "normal" climate, but the definition of normal seems to be changing quickly, with potentially dangerous consequences. "That is exactly what is playing out now, with a region of the country largely devoid of air conditioning suffering through unheard-of temperatures over a prolonged stretch of time," writes Andrew Freedman.

• How rare? The intensity of the heat wave in the Northwest is a once-in-1,000-year event, at least based on historical models, and possibly even a once-in-10,000-years event, writes Jeff Berardelli at CBS News. But as the Oregon Climate Office tweets, the problem with such statements is that "the past is no longer a reliable guide for the future. These events are becoming more frequent and intense, a trend projected to continue."
• The dome: At play in all this is what's known as a "heat dome," which occurs when "the atmosphere traps hot ocean air like a lid or a cap," per the National Oceanic and Atmosphere Administration. The Washington Post also has an explainer, one written earlier in the month when a different heat wave roasted an area from Nebraska to California. "Hot air masses expand vertically into the atmosphere, creating a dome of high pressure that diverts weather systems around them," per the story by the newspaper's Weather Gang. This sets off a "vicious feedback loop" in which clouds dissipate and the sun bakes the ground. If the ground is already parched through drought, as has been the case in California, the feedback loop becomes even more intense.
• The dome, II: In layman's terms, the dome "is essentially acting as an oven to bake the region," writes Madeline Holcombe at CNN. High pressure is the atmospheric lid that stops hot air from rising and forces it back to the surface, where it heats up even more. "Imagine a swimming pool when the heater is turned on—temperatures rise quickly in the areas surrounding the heater jets, while the rest of the pool takes longer to warm up," per the NOAA.
• Familiar culprit named: The Axios post pins the blame for all this on human-caused climate change and quotes a worried climate scientist to that effect: "Because of the fact that climate change has made heat waves like this much more likely and intense, we might very well reach the tipping point of what our infrastructure and other societal systems are able to deal with," says Friederike Otto of the University of Oxford.

(More heat wave stories.)