Record Heatwaves in Pacific Northwest Upend Predictive Models

Posted: August 24, 2021 4:48 am

The June heatwaves in the Pacific Northwest this year was a 1-in-1000 year event, according to the World Weather Attribution project. But then came July–and August. Let’s take a look at exactly what that means, how it happened–and what it means for the future.

Record Heat Waves

The first heatwave of the Pacific Northwest saw temperatures of over 100 degrees and declarations of gross statistical anomaly, but just a week after record-breaking deviations from normal seasonal temperatures, it happened again. Just how hot was it?

June

Over a three day period between the 26-29 of June, all-time records were broke all over the Northwest. Roads buckled, windows and buildings could not withstand the heat, and because most in the Pacific Northwest do not have air conditioning, heat stroke for many became a reality.

In Portland, Oregon, the highs were easily the most extreme temperatures the city had ever seen. 108, 112, and 116 degree days consecutively on the days of June 26-29 were the highest ever recorded. In Seattle, the record highs were 104 followed by 108 degrees. For context, the average temperature in June in Seattle is anywhere from 69-74 degrees. Before this June, the city had only ever reached degrees of 100 or higher three times in the last 100 years. The coast of Washington too had its share of astounding heat, with highs that were 45 degrees above the average temperature for the month–and 11 degree above the previous record high.

In British Columbia reached a high not only for its region but for the entire country of Canada on June 27 with a sweltering 116 degrees, only for area to break its own record the next day when temperatures soared to 118, and the next day again at an unbelievable 121 degrees in Lytton, BC, which was evacuated the following week as it burned to the ground. And on the same day, that record was met in six other locations around Canada. The average temperature in BC in June is 67 degrees.

July

After the record-breaking heat of June, scientists had already begun to predict that such an occurrence was very unlikely to happen again, mostly due to the extreme numerical difference between the previous highs and the new records and the time that has passed between the previous high and the current one. Accommodating record extremities on a previous model will normally include the analysis that such an occurrence is unlikely to happen again, because it never has before. However, given massive heatwaves in June, all of which were dramatic anomalies, what would happen in July was anyone’s guess. New models were being created already, and fresh concern was injected into the climate change discussion.

July brought a drought to the area and the second major heatwave of the summer. Ninety-three percent of the Pacific Northwest was experiencing drought as July began–a 40% jump from the previous months. South-Central Oregon lost 360,000 acres to fire alone, with over 40 fires burning simultaneously across Oregon, Washington, and Idaho. Yakima and Olympia in Washington and Oregon’s Willamette Valley were under heat advisories yet again–but this time, the high only reached 98 degrees.

August

So what happened in August? Heat-weary residents could only hope. Heat domes yet again incinerated the region as Oregon governor Kate Brown declared a state of emergency and residents were urged to turn off any unused power in their homes. Portland reached 102 degrees on August 11, with many libraries and community centers opening up as cooling centers for the city’s homeless. A possible 100 people died of heat related causes in Oregon in August. Road crews had to cool off Seattle’s steel bridges with water to keep them from expanding and becoming unstable.

Why Is This Happening?

A high pressure system, sinking air, and cloudless skies combined over the region and did not budge for days as temperature rose. In some areas, wind was thrown into the already-extreme mix, blowing in air from high elevation to low elevation due to the topographical nature of the region. Mountains and plateaus are common all over the Pacific Northwest and into Idaho, and this sinking air compressed, creating an even hotter environment. This type of wind activity from mountains down into the plateaus is not uncommon on the west coast; however, the high pressure system that preceded it certainly was.

What Does It Mean?

Wildfire is the most direct and immediate consequence of this extreme weather, with fires stretching over more than a quarter of a million acres in Northern California. The extreme dry conditions of such abnormal heat evaporates moisture and, in the case of the Dixie Fire in northern Cali, produced a fire tornado or swirling wind. The large danger in extreme moisture evaporation is what is known as a “dry thunderstorm” where moisture is eviscerated by heat before it even leaves the clouds, eliminating the respite that rain would normally provide when lightning strikes dry brush and ignites it.

Will It Continue?

One of the most pervasive questions is whether we can expect an increase in heat averages each year in the future. In June, the World Weather Attribution project stated that the heatwave (the first of three) was a 1 in 1000 year occurrence–and likely would not happen again form any years. This was quickly proven not to be the case–however, previous to June, that prediction would have been true.

Climate scientists are in agreement that without global warming, these heat waves would never have occurred–but there are varying opinions on whether global warming triggered a sudden statistical anomaly or whether this is a sign of an actually altered climate.

In order to to understand the actual significance of analysis, we have to first look at how the analysis was achieved–i.e., what models were used and why this event is considered a statistical anomaly according to those models. Admittedly, the models themselves operate under a lot of assumptions–namely that the current happenings of global warming will continue to accelerate at the rate they are accelerating rather than in an exponential acceleration or whether new events change the model altogether.

Yearly increases in temperature averages throw off a models’ ability to even determine an average–sort of like the “sliding goalposts” soccer analogy. What it basically means is that without sustained averages over a long period, there is no real way to determine what is actually unusual, because the average which extremes would normally be compared to to determine said unusual activity is itself constantly changing. Greenhouse gas emissions are not stable–meaning that the level of emissions are not the same each year, and actually continue to increase (as do the levels of acidity in the ocean and the amount of carbon in the atmosphere). This correlation was the base of NOAA’s Geophysical Fluid Dynamics Laboratory study that examined greenhouse gas emissions alongside heat waves throughout the country. This study ended up creating an entirely new model that predicted 1.2 to twofold increase in heatwaves in the next 30-60 years as compared to the numbers from 1970-2000.

Considering that summer is, for all intents and purposes, at the beginning of the end, it may well be the case that the Pacific Northwest is spared another damaging heatwave. But city and state officials and administrators are already preparing for next summer, looking into air conditioning for buildings, heat-safe exteriors and windows, and longer-term cooling center solutions for outdoor workers and the homeless. Whether this is actual climate change remains to be seen, but in the meantime, they are preparing for anything.

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