Extreme Temperature Diary- Wednesday September 7th, 2022/ Main Topic: What Is a Heat Dome?

The main purpose of this ongoing blog will be to track global 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: What Is a Heat Dome?

Dear Diary. Sometimes as a scientist it is good to step back and better define terms for laypeople so that they better understand messages that we are trying to convey. Many times, I will be describing heatwaves with the term “heat dome,” measured in decameters, being asked what this term is. For a more complex definition, here is what I wrote a few years ago:

Heatwaves and their associated heat domes have made big news this summer across the Northern Hemisphere. Here is a recent article from The Conversation describing just exactly what they are:

https://theconversation.com/what-is-a-heat-dome-an-atmospheric-scientist-explains-the-weather-phenomenon-baking-california-and-the-west-185569

What is a heat dome? An atmospheric scientist explains the weather phenomenon baking California and the West

Published: June 22, 2022 8.35am EDT Updated: September 5, 2022 2.07pm EDT

Temperatures broke records in California over Labor Day weekend 2022, and the forecast for Sept. 6 was well above normal across the U.S. West. National Weather Service

Author: William Gallus Professor of Atmospheric Science, Iowa State University

A heat dome occurs when a persistent region of high pressure traps heat over an area. The heat dome can stretch over several states and linger for days to weeks, leaving the people, crops and animals below to suffer through stagnant, hot air that can feel like an oven.

Typically, heat domes are tied to the behavior of the jet stream, a band of fast winds high in the atmosphere that generally runs west to east.

Normally, the jet stream has a wavelike pattern, meandering north and then south and then north again. When these meanders in the jet stream become bigger, they move slower and can become stationary. That’s when heat domes can occur.

Heat domes involve high-pressure areas that trap and heat up the air below. NOAA

When the jet stream swings far to the north, air piles up and sinks. The air warms as it sinks, and the sinking air also keeps skies clear since it lowers humidity. That allows the sun to create hotter and hotter conditions near the ground.

If the air near the ground passes over mountains and descends, it can warm even more. This downslope warming played a large role in the extremely hot temperatures in the Pacific Northwest during a heat dome event in 2021, when Washington set a state record with 120 degrees Fahrenheit (49 Celsius), and temperatures reached 121 F in British Columbia in Canada, surpassing the previous Canadian record by 8 degrees F (4 C).

The human impact

Heat domes normally persist for several days in any one location, but they can last longer. They can also move, influencing neighboring areas over a week or two. The heat dome involved in the June 2022 U.S. heat wave crept eastward over time.

On rare occasions, the heat dome can be more persistent. That happened in the southern Plains in 1980, when as many as 10,000 people died during weeks of high summer heat. It also happened over much of the United States during the Dust Bowl years of the 1930s.

A heat dome can have serious impacts on people, because the stagnant weather pattern that allows it to exist usually results in weak winds and an increase in humidity. Both factors make the heat feel worse – and become more dangerous – because the human body is not cooled as much by sweating.

The heat index, a combination of heat and humidity, is often used to convey this danger by indicating what the temperature will feel like to most people. The high humidity also reduces the amount of cooling at night. Warm nights can leave people without air conditioners unable to cool off, which increases the risk of heat illnesses and deaths. With global warming, temperatures are already higher, too.

One of the worst recent examples of the impacts from a heat dome with high temperatures and humidity in the U.S. occurred in the summer of 1995, when an estimated 739 people died in the Chicago area over five days.

This article was updated Sept. 5 with the heat wave in the West.

Here are some “ET’s” recorded from around the planet the last couple of days, their consequences, and some extreme temperature outlooks. Incoming Wednesday records from Falkor will be listed first:

Here is some more August and Summer 2022 climatology:

Here is more climate and weather news from Wednesday:

(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.)

(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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