A bizarrely stagnant weather pattern called an “omega block” has been dominating the atmosphere over North America, delivering a historic May snowstorm that buried parts of the country. Just as unusual, however, has been the warm side of the system, which has brought high temperatures up to 35 degrees above average.
Records have toppled far and wide across the Intermountain West, the interior Pacific Northwest and especially western Canada — including in Alberta, Saskatchewan, Manitoba, the Northwest Territories and even Nunavut. Perhaps the most extreme was an 88-degree reading in Hay River, Northwest Territories, where highs should be in the lower to mid-50s this time of year.
Hay River is located at about 60.5 degrees north latitude, about as far north as Helsinki, Anchorage or Reykjavik, Iceland. It’s about 430 miles south of the Arctic Circle.
Maximiliano Herrera, a climate historian known for keeping track of temperature records, described the readings as “extraordinary.” In a tweet, he said the temperatures were “several degrees above anything seen that early.”
Fort Providence, even farther north in the Northwest Territories, got to 82.6 degrees.
Instigating the extreme warmth is a dramatic northward meandering of the jet stream, or the river of wind in the upper atmosphere that divides heat near the equator from frigid air banked up over the North Pole. That jet stream dip — within which was nestled a pocket of cold air, low pressure and spin at high altitudes — dove south over the West Coast. Then the jet stream surged into Canada, cresting north of a stagnant ridge of high pressure known as a heat dome.
This high brought hot, sinking air that dried out and heated up further, simultaneously deflecting any inclement weather and squashing attempts at cloud cover. And because the jet stream deviated so far north, warm air was able to slide hundreds of miles north of where it otherwise ordinarily would be. In addition to the nearly 90-degree readings that were logged in northern Canada, a menagerie of records were set in the Lower 48. Among them:
Missoula, Mont., hit 90 degrees Monday, not only setting a daily record, but also marking the second-earliest 90-degree reading on record and the hottest Missoula has been this early in the year since 1910. The city also got to 88 degrees Wednesday, beating the 84-degree record set in 1985.
Buffalo, Wyo., hit 76 degrees Wednesday, tying a record set in 2000.
Lake Yellowstone, Wyo., tied a record of 59 degrees Wednesday; the record was last reached in 2004.
Ellensburg, Wash., got to 86 degrees Wednesday, surpassing the record of 85 set in 1946.
Spokane, Wash., nabbed a record two days in a row. Wednesday’s high of 84 degrees beat the 83 set in 1918.
Brigham City, Utah, snagged a 82-degree reading Tuesday, tying a record from 2007.
Canada tabulated a large number of records. Among them was the 78.1 degrees that Banff hit, beating the record of 75. Records there date to 1887.
Edmonton was the hottest of the major cities in Canada, reaching 84.9 degrees. Averages are in the mid-60s. Calgary got to 78.4 degrees, narrowly edging out a record set in 1890.
While it’s impossible to assert that these specific record readings were caused by human-induced climate change, it is accurate to state that episodes of unseasonable heat are made more frequent, probable and intense due to human action. In a world unperturbed by humans, one might expect a roughly equal ratio of hot to cold records. Instead, heat records continue to vastly outpace cold records, and extreme,