Extreme Temperature Diary- Friday July 21st, 2023/Main Topic: Heatwave Chevron to Last Through July and Perhaps Beyond

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: Heatwave Chevron to Last Through July and Perhaps Beyond

Dear Diary. You know that the United States and other countries around the world are having a bad historic heatwave when the thing lasts for most of the summer with not much of a letup. It now appears that will be the case in the Southwest where Pheonix recorded its 21st consecutive day with a max above 110°F. The heat dome in association with Heatwave Chevron will continue to wax and wane but will be anchored over the Southwest through the end of July and perhaps into August.

First. the good news. A fairly strong cold front by July standards will sweep through the Southeast and will end dangerous heat there at least temporarily. By this weekend maxes across most of the Southeast will only be in the 80’s:

Now the very bad news. The core of Heatwave Chevron centered over the Soutwest will get weaker over the weekend, but that process will be temporary. The thing will grow in all directions again such that by the middle of next week for the first time this summer portions of the Midwest will be seeing triple digit temperatures:

Dangerous heat will also be moving back into the Southeast.

Here is what we see at 500 millibars by Wednesday, corresponding to the above chart:

Notice that the heat dome is centered over New México at about 598 decameters and is nosing into the Midwest and Southeast. It’s no wonder that forecast maxes from models are as hot as those on the Pivotal Weather chart that I displayed today.

The situation gets worse as we head closer to August with the upper-level ridge expanding more towards the Northeast as shown from this set of model ensembles:

We probably will see a sprawling area of 594+ decameter heights from coast to coast the last few days of July. It’s no wonder that we are seeing 6-10 day outlooks like this:

Here is a brand-new summary of Heatwave Chevron and outlook for it from my friends at the Washington Post:

Why this summer’s heat is so exceptional across the Southern U.S. – The Washington Post

Inside the most extreme heat wave the Southern U.S. has faced

The exceptional heat will be remembered for its intensity and duration

By Matthew Cappucci and Dylan Moriarty

July 21, 2023 at 6:00 a.m. EDT

The summer of 2023 has featured the most intense heat in modern records averaged over the planet. June was Earth’s hottest on record, and the oceans are exhibiting unprecedented warmth. Far and wide, already-exceptional weather events are being pushed into record territory by the effects of human-caused climate change.

In the Lower 48 states, global warming has manifested itself in a historically intense and prolonged heat wave, stretching from California’s interior to South Florida. The zone from Arizona to Texas has sat at the center with record-shattering heat enduring for at least three weeks and showing little sign of relenting.

As brutal heat wave sweeps southern U.S., more records to fall

A concentrated sphere of heat, known colloquially as a “heat dome,” has powered the excessively high temperatures. Over the coming week, the heat dome will reach from coast to coast, inching northward and parking smack dab in the middle of the country. Over the next 8 to 14 days, the National Weather Service is calling for above-normal temperatures nearly everywhere in the continental U.S.

This massive heat dome is one of several affecting the planet, bringing all-time records in parts of Europe and in China and alarmingly hot sea-surface temperatures to the Atlantic. While heat domes form every summer, recent years have featured a string of particularly anomalous heat waves.

“Human influence has likely increased the chance of compound extreme events since the 1950s,” reads the most recent assessment from the United Nations Intergovernmental Panel on Climate Change. “This includes increases in the frequency of concurrent heat waves and droughts on the global scale.”

In other words, what we’re witnessing now — multiple simultaneous record-setting heat domes globally — is exactly what scientists expect as increasing greenhouse concentrations from human activities warm the planet.

A heat dome of exceptional strength and duration

Beneath the heat dome baking the southern U.S., numerous cities have set record highs. Reno, Nev., and Grand Junction, Colo., tied all-time records of 108 and 107 degrees on Sunday and Monday, respectively. Other cities came very close. Salt Lake City fell a degree shy of its all-time record at 106 degrees, as did Las Vegas, at 116.

How bad is heat risk near you?

(The Washington Post)

We’re tracking dangerous heat waves across the United States daily. Look up your city to see extreme heat risks near you.

Phoenix also registered its all-time warmest low temperature on Wednesday, dropping to just 97 degrees, to produce an average daily temperature of 108.0 degrees, its highest on record.

The top 10 hottest nights on record in Phoenix have all occurred in the past 20 years despitenearly 130 years of continuous bookkeeping. That’s probably a symptom of both warming from greenhouse gas emissions and the urban heat island effect, or the expansion of buildings and paved surfaces that elevates city temperatures.

As a testament to the heat wave’s longevity, Phoenix has reached a high of at least 110 degrees on a record 21 straight days, while its low has been at or above 90 degrees on a record 11 nights in a row. Weather models indicate there’s a chance that Phoenix will continue its string of 110-degree highs through at least the end of the month.

Phoenix is also on pace to be the first American city to have an average temperature of 100 degrees or greater for any calendar month.

It’s not just Phoenix that can’t shake the heat. El Paso has reached at least 100 degrees on a record 35 straight days and counting; the city’s previous record was 23 days during a streak back in midsummer of 1994.

New Orleans, which hasn’t received as much attention as locations to the west, is heading for its warmest summer on record. The brutal heat has routinely combined with oppressive humidity to push heat indexes into the 100- to 108-degree range.

And in Florida, Miami has had 40 days in a row with a heat index over 100, during which there was a 16-day stretch when heat index values eclipsed 105. The previous records for both were 32 days and eight days, respectively.

Simply stated, there are no analogues, or comparable heat waves, in the data that rival the unusual synergy between intensity and duration that the Southern U.S. is facing right now.

Heat around the world

The Southern U.S. isn’t alone. Three other heat domes have been shattering records globally:

  • European heat dome helped Rome spike to 109 degrees on Tuesday; the city’s previous record was 105. All-time heat records were also set in Spain.
  • In Asia, Sanbao, China, hit 126 degrees Sunday, a national record. It represented the highest temperature ever observed north of 40 degrees North latitude.
  • A heat dome over the Atlantic has contributed to record warm water temperatures. The margin by which the record has been achieved is staggering, too. The North Atlantic’s average temperature is a little over 1 degree warmer than the previous record holder.

A climate connection

Hot weather, and even extremely hot weather, are expected during the summer. But the human influence on the climate system is supercharging extremes.

“If global warming increases, some compound extreme events with low likelihood in the past and current climate will become more frequent,” warned the IPCC. “There will be a higher likelihood that events with increased intensities, durations and/or spatial extents unprecedented in observational record will occur.”

In plain language, things that we haven’t seen before — including from a magnitude and duration standpoint — are now entering the realm of physical possibility, and will only become more severe as the climate warms further.

Heat dome animation by Artur Galocha

More on extreme heat

Our warming climate: As more heat records are expected to fall,July will be Earth’s hottest month on record.Here’s why the sweltering heat wave isn’t moving anytime soon. At Earth’s hottest spots, heat is testing the limits of human survivalLook up your city to see your extreme heat risk with our tracker. Take a look at what extreme heat does to the human body.

How to stay safe: It’s better to prepare for extreme heat before you’re in it. Here’s our guide to bracing for a heat wave, tips for staying cool even if you don’t have air conditioning, and what to know about animal safety during extreme heat. Traveling during a heat wave isn’t ideal, but here’s what to do if you are.

Understanding the science: Sprawling zones of high pressure called heat domes fuel heat waves. Here’s how they work. You can also read more about the link between weather disasters and climate change, and how leaders in the U.S. and Europe are responding to heat.

By Matthew Cappucci Matthew Cappucci is a meteorologist for Capital Weather Gang. He earned a B.A. in atmospheric sciences from Harvard University in 2019, and has contributed to The Washington Post since he was 18. He is an avid storm chaser and adventurer, and covers all types of weather, climate science, and astronomy. Twitter

By Dylan Moriarty Dylan Moriarty is a graphics reporter and cartographer at The Washington Post. Twitter

Here are some other “ET’s” recorded from around the planet the last couple of days, their consequences, and some extreme temperature outlooks, as well as any extreme precipitation reports:

Here is more new June and July 2023 climatology:

Here is more climate and news from Friday:

(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.)

Today’s News on Sustainable and Traditional Energy from Fossil Fuel:

More Environmental Stuff:

More from the Weather Department:

More on other science and the beauty of Earth and this universe:

If you like these posts and my work on record temperature ratios, 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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