Heat dome is here: It will feel like 100 degrees-plus to 100 million of us
AccuWeather says that almost 200 million people will experience the triple digit "RealFeel" temperatures on Friday alone. The National Weather Service early on July 22 already had issued extreme heat warnings, watches and advisories across a swath of the nation, affecting more than 70 million Americans.
Many cities that have not seen actual 100-degree temperatures so far this summer will hit the mark this week, AccuWeather warns. Many areas from Nebraska and Missouri to Texas and Louisiana won't even see overnight temperatures drop below the mid-70s or even low 80s.
"Kansas City, Missouri, has not hit 100 degrees since Aug. 25, 2023, but is positioned to do so on multiple days during the upcoming heat dome," AccuWeather Senior Meteorologist Chad Merrill said.
Much of the East was exempt from the heat dome on July 22 as residents in this suburb of Washington, D.C., saw temperatures drift into the 60s overnight with little humidity. The high for July 22 was forecast to reach only the mid-80s. The respite, however, won't last − by Friday the humidity returns with a forecast high nearing 100 degrees.
Heat dome to push extreme temperatures across much of US this week
What is a heat dome?
Heat dome is not actually a scientific term, according to climatecheck.com, which says the term does effectively describe the "oppressive" high-pressure atmospheric systems that cause warm air to be pushed to the Earth's surface and trapped there for long periods of time.
"The dome traps high-pressure air in one place, like the lid on a pot," the website says. "These large zones of hot air result in a combination of blistering temperatures, devastating wildfires, and drought conditions."
The symptoms of heat stroke: What to know amid extreme heat warnings
How long will the heat dome last?
Jonathan Erdman, a senior meteorologist at weather.com, wrote that the heat wave may last until at least the last weekend of July in the Plains and South, while slowly expanding west toward the Rockies.
"Our longer range outlooks suggest the Northeast has the best chance of eventually seeing some heat relief around that last weekend of July," Erdman said.
'Corn sweat' will add to punishing heat, humidity in Midwest this week
Corn sweat adding to Midwest heat, humidity
It's high summer in the Midwest and the corn is "sweating." Known as evapotranspiration, it's a healthy process for plants that can worsen stifling heat for humans by driving up humidity levels. The process is how plants release water vapor into the atmosphere. The released water combines with other water molecules, humidifying the air.
In the Plains and Midwest regions, where there are millions of acres of corn and soybean crops, it makes a difference. In Iowa, corn pumps out "a staggering 49 to 56 billion gallons of water into the atmosphere each day" throughout the state, the National Weather Service said. That can add 5 to 10 degrees to the dew point, a measure of the humidity in the air, on a hot summer day. Read more here.
− Doyle Rice
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