Extreme Temperature Diary- Tuesday June 29th, 2021/ Main Topic: Reports From Pacific Northwest Heatwave Beta…Day 4/The “Heatbomb”

The main purpose of this ongoing blog will be to track planetary extreme or record temperatures related to climate change. Any reports I see of ETs will be listed below the main topic of the day. I’ll refer to extreme or record temperatures as ETs (not extraterrestrials).😉

Main Topic: Reports From Pacific Northwest Heatwave Beta…Day 4/The “Heatbomb”

Dear Diary. On Monday Seattle soared to an all-time record of 108°F and Portland a much worse 116°F. These figures along with many others noted from British Columbia southward through Oregon are leaving meteorologists and some climatologists aghast:

Four days ago the Pacific Northwest was experiencing a near normal temperature regime. The area did not have a slow warming trend leading to torrid temperatures. Instead a “four sigma” heat dome rapidly built over the area causing all-time records within the space of three days by Sunday. Yesterday I heard the term “heatbomb” for the first time in association with my dubbed Heatwave Beta and with good reason.

A heatbomb would be similar to a cyclone bomb in which temperatures rise about as fast as pressure lowers for the cyclone bomb. If the term catches on in meteorological circles as the climate crisis deepens as the 21st century rolls along, better defining parameters will be made. Certainly more common rapidly forming heat domes of three or beter sigma are in our future if we don’t finally limit carbon pollution.

Due to some onshore marine influence the extreme heat has ended as fast as it began in Portland and Seattle, I’m glad to report. Extreme heat will continue, though, east of the Cascades and will be building into Montana and central Canada today and on Wednesday as the heat dome moves eastward:

It will be amazing to see that Canada will be suffering from more extreme heat that the United States by Wednesday.

As far as our categorization of heatwaves goes, I thankfully have not seen any news of heat related deaths from the Pacific Northwest. Certainly any death count won’t come close to that of the 700+ number from the CAT4 Chicago heatwave of 1995. The number of all-time records set in Sunday and Monday with reports of roads buckling would warrant a historic CAT4 ranking those days. Today not so much, and the heatwave has broken in Seattle and Portland, so Beta goes down to a CAT3 for Tuesday.

.Here are many more details from the latest Washington Post article:


Behind the unprecedented heat baking the Pacific Northwest

Matthew Cappucci, Jason Samenow  42 mins ago

Temperatures across the Pacific Northwest have spiked to unheard-of levels while populations struggle to cope. Canada shattered its all-time temperature record Monday when Lytton, British Columbia, shot to up 118 degrees — higher than any temperature ever observed in Las Vegas.

map: Temperature difference from normal Tuesday in Washington and Oregon as predicted by the European model. (WeatherBell)

Temperature difference from normal Tuesday in Washington and Oregon as predicted by the European model. (WeatherBell)

Numerous locations in Oregon and Washington state have broken all-time records by large margins, in some cases on two or three consecutive days. They include Seattle, which soared to a sizzling 108 degrees Monday and Portland, which surged to 116.

Although the worst of the heat has departed Seattle and Portland, temperatures have yet to peak in areas farther east in the interior of Oregon and Washington, as well as extensive parts of western Canada. The prolonged, exceptionally high temperatures pose a grave health risk for older adults and vulnerable populations without easy access to air conditioning.

Portland, Seattle and Canada crush all-time heat records for second straight day

The ongoing event affecting the northwestern United States and adjacent Canada is firmly within uncharted territory because of a combination of weather effects and climate-driven warming.

The weather

background pattern: Visualization of heat dome over Pacific Northwest Monday. (earth.nullschool.net)

Visualization of heat dome over Pacific Northwest Monday. (earth.nullschool.net)

At its core, this event is being driven by an exceptionally strong heat dome. Heat domes, or sprawling ridges of high pressure, are a staple of summertime. They bring copious sunshine and sinking air that heats up as it is compressed.

diagram: Hot air masses expand into the atmosphere, creating a dome of high pressure that diverts weather systems around them© Artur Galocha/The Washington Post Hot air masses expand into the atmosphere, creating a dome of high pressure that diverts weather systems around them

This particular heat dome itself is unprecedented for its strength in the Pacific Northwest. It has blown away records based on measurements from three miles high in the sky down to the ground.

This heat dome may have been pumped up by a tropical storm in the Pacific interacting with the jet stream last week, Oregon’s state climatologist Larry O’Neill told the Capital Weather Gang.

The timing of the heat dome has helped maximize its impact. Because it is occurring near the summer solstice, the added daylight is giving the heat dome extra time to increase temperatures, said Rebecca Muessle, a meteorologist at the National Weather Service office in Portland.

Wind directions have played a crucial role in the coverage and magnitude of the excessive heat. The high-pressure system has been centered near the International Border, with clockwise flow around it bringing easterly winds for much of the Columbia River Basin and, broadly, Idaho, Washington and Oregon.

chart: A model simulates air wrapping clockwise around high pressure at high altitudes before curving around and subsiding closer to the surface in the Pacific Northwest. (NOAA)

A model simulates air wrapping clockwise around high pressure at high altitudes before curving around and subsiding closer to the surface in the Pacific Northwest. (NOAA)

Between Saturday and Monday, the easterly winds helped push the coastal marine layer, or zone of ocean-chilled air, back over the water, permitting the heat to extend into the Interstate 5 corridor from Seattle to Medford and even to the coast in some areas.

This wind direction has also promoted “downsloping,” or the downhill movement of air, in this case descending from the Cascades through the I-5 corridor. When pockets of air move downhill, they are compressed by the increasing air pressure near the ground and subsequently warm up.

Between Saturday and Monday, the downslope flow was further enhanced by a zone of low pressure off the coast of Northern California. Muessle called this low a “big player” in the intensity of the heat west of the mountains by “bringing in the warmer air that you typically see east of the Cascades.”

But as the low-pressure area weakened and shifted to the north late Monday, it allowed onshore flow or winds off the ocean to return to coastal areas which brought dramatic cooling.

Portland saw its biggest overnight drop in temperature on record between Monday evening and Tuesday morning, as the mercury plummeted 52 degrees, from 116 to 64.

“It was very very nice, a much-needed break,” Muessle said.

But this onshore wind won’t offer relief for interior locations which are predicted to bake under the heat dome for the next several days.

The climate

map: Temperature anomalies at the mid-levels of the atmosphere. (WeatherBell)Temperature anomalies at the mid-levels of the atmosphere. (WeatherBell)

A heat wave of this magnitude required weather systems and winds to align, but it could not have been this extreme without human-caused climate change.

The role of climate change has been to substantially increase the likelihood of record-breaking temperatures.

Simple logic dictates that a climate experiencing a background warming of several degrees will be more prone to hotter heat events. It’s like a slam dunk in basketball — if the floor rises, it becomes easier to score.The Pacific Northwest heat wave is shocking but shouldn’t be a surprise

“Summers in the Pacific Northwest are about three degrees warmer today than 50 or 100 years ago,” said Zeke Hausfather, a climate scientist at the Breakthrough Institute. “All things equal, we would think a heat wave today would be about 3 degrees warmer.”

Such warming, Hausfather explained, means exceptionally strong heat waves, such as this, become more frequent.

“Heat waves that used to occur 1-in-1,000 year events are becoming 1-in-100 year events and 1-in-100 year events are becoming 1-in-20,” he said.

In addition, drought, which has connections to climate change, is playing a role as both a cause and effect of the ongoing heat. Fifty-five percent of the West is experiencing an extreme or exceptional drought — the two most severe categories — including about a quarter of Washington and nearly a third of Oregon. Dry air heats up considerably faster than humid air. That means the same input of heat can foster a higher temperature.

Research shows climate change has worsened the “megadrought” over much of the West, since warming temperatures dry out the land surface more quickly.The western U.S. is locked in the grips of the first human-caused megadrought, study finds

Looking ahead, observed temperatures associated with the heat wave are actually helping to dry out the area even further, while the impetus for the heat — high pressure — diverts precipitation and storm systems to the north. That will make hot temperatures even tougher to shake.

Finally, it’s possible that climate warming has changed the jet stream to increase the strength of hot weather patterns such as what we’ve seen in the Pacific Northwest this week.

Michael Mann, a climate scientist at Pennsylvania State University, with colleagues, published a study in 2018 that connects summer weather extremes with a fundamental change in how the jet stream is behaving during the summer: Study: Freak summer weather and wild jet stream patterns are on the rise because of global warming

Hausfather said “robust debate” continues in the scientific community as to the role of climate change on jet stream patterns.

Other notes on Heatwave Beta:

Here are some of Tuesday’s “ET’s”:

Here is more climate and weather news from Tuesday:

(As usual, this will be a fluid post in which more information gets added during the day as it crosses my radar, crediting all who have put it on-line. Items will be archived on this site for posterity. In most instances click on the pictures of each tweet to see each article. The most noteworthy items will be listed first.)

Now here are some of today’s articles and notes on the horrid COVID-19 pandemic:

(If you like these posts and my work please contribute via the PayPal widget, which has recently been added to this site. Thanks in advance for any support.) 

Guy Walton “The Climate Guy”

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