The Pacific Northwest will continue to be boiling over the next few days with cities in the region seeing all-time record highs, reports CBS News. On Saturday, Portland, Oregon, reached 112ºF while Seattle easily broke 100ºF and Redding, California, hit 113º F.
Temperatures are expected to continue to stay in record-high zones for Monday and Tuesday as well, with experts calling the heatwave a once-in-a-millennium event. But just what is causing these record highs? A phenomenon known as a heat dome.
According to National Geographic, a heat dome is an area of high pressure over a region that has bubbled up from the normal pattern of the jet stream. The heat dome wraps upwards from the jet stream, curves around an area, and then wraps back down, rejoining the stream—and thus giving it an omega (Ω) shape. The high pressure essentially puts a lid on the omega, creating a dome that keeps everything in the affected area boiling hot.
The punishing heatwave has an incredible jet stream pattern.
The dome of heat will be encircled by the polar jet and this helps lift a sub-tropical jet branch almost into the Canadian Arctic. pic.twitter.com/uIWIIINlSc
— Scott Duncan (@ScottDuncanWX) June 25, 2021
Is the current heat dome due to global warming? With the region seeing once-in-a-millennium highs, it’s reasonable to assume so. It will be a little while before scientists can say for sure, but many have already theorized that the jet stream omega warping could be due to the increasing temperatures in the arctic.
To put climate extremes into perspective we measure against the average. The sigma is the standard deviation of a normal distribution of expected values. In this case the heat dome sigma max is 4.4 – that means it's outside of 99.99% of expected values or a 1/10,000+ chance (1/2) pic.twitter.com/8raIMAngkg
— Jeff Berardelli (@WeatherProf) June 27, 2021
That’s bad news for us. Because if arctic warming is causing the current heat dome, we can expect to see these events becoming common in the years ahead as fossil fuels continue to heat the earth’s climate.