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Record-breaking central U.S. heat dome brings ‘life-threatening’ conditions

THE BRIEF

• July 2023 was hotter than any July since at least 1880, according to the National Oceanic and Atmospheric Assn.
• The past 47 consecutive Julys have been above the 20th century temperature average
• The El Niño climate pattern could make 2023 the hottest year on record

What we know: A heat dome is a weather phenomenon where high pressure in the upper atmosphere traps hot air near the ground. This leads to an extended period of extremely hot weather in a particular region. It’s like a lid on a pot, trapping heat and causing temperatures to soar.

What we don’t know: During a heat dome, the sinking air within the high-pressure system allows the air to warm up and prevents the normal movement of cooler air from coming in, creating a situation where temperatures can climb rapidly and remain high for an extended period. This weather pattern can result in heatwaves, posing serious health risks and stressing infrastructure like power grids as people try to keep cool. It’s a reminder of how interconnected our weather systems are and how certain patterns, like a heat dome, can significantly impact local climates.

Dynamics Behind the Phenomenon

The mechanism driving a heat dome involves the sinking of air within the high-pressure system. As the air descends, it compresses and warms, amplifying the existing heat. Simultaneously, the descending air inhibits the circulation of cooler air, preventing its infiltration into the affected region. This results in a prolonged period of intense heat, often marked by sweltering temperatures and diminished chances of precipitation.