What is a heat dome and why is it engulfing the South?

Heat domes form when high-pressure systems trap heat in a certain location
Domes aren’t uncommon, but this one is unusual as it’s early and more humid
Blazing temperatures are to blame for 13 deaths in Texas, 1 in Louisiana

Updated: Jun 29, 2023 / 06:15 AM CDT

DALLAS (NewsNation) — Scorching heat is blamed for at least 13 deaths in Texas and another in Louisiana as more than 100 million people across the country are facing warnings of dangerous, triple-digit temperatures.

However, this current summer heatwave is not typical, according to scientists.

A weather phenomenon called a “heat dome” is to blame. It’s hovering over Oklahoma, Texas and Louisiana and expanding across the south as far as Arkansas, Kansas, Florida and the Great Plains.

While you can’t physically see a heat dome, it is sucking in hot, dry air from the desert in the West as well as heat from the sun and the ground and trapping it over a certain location like a lid.

A heat dome occurs when a high-pressure system is “stuck” in a certain location and holds the heat in. According to the National Oceanic and Atmospheric Administration, the atmosphere acts like a lid or cap over a region and traps in the hot ocean air.

With the absence of rain and clouds, the situation continues to worsen.

“During the daytime, the air gets exchanged with the ground and higher up and consequently with the temperatures aloft being hot that air gets brought down to the ground and heats up, if it had cooler air aloft the air would be much cooler also,” said John Nielsen-Gammon, a Texas A&M atmospheric sciences professor.

Heat domes aren’t uncommon.

Nielsen-Gammon said at least one heat dome forms somewhere in the U.S. during the summer. However, what makes this heat dome remarkable is its early occurrence in the summer and the higher level of humidity with it.

In Texas, there’s significant concern regarding whether the energy grid can withstand such extreme weather.

So far, the grid has managed to withstand the intense heat. One contributing factor to its stability is the utilization of solar power, which reportedly supplied nearly 20% of the record energy demand earlier this week.

According to the National Weather Service, the millions of people affected by this heat dome might not experience relief until around the Fourth of July holiday.