Heat dome vs heat wave: What’s the difference and why it matters
Heat wave or heat dome? Here’s the difference — and why some extreme heat lasts longer and feels more dangerous.
- A significant heat wave is expected to bring dangerous temperatures to much of the central and eastern U.S.
- The heat dome will cause temperatures in the 90s to low 100s, with heat indices reaching up to 115 degrees.
- This period of extreme heat is forecasted to last through the Independence Day weekend, until around July 6.
A “significant” heat wave is on the way.
According to the latest forecast from the Weather Prediction Center, dangerous heat is expected across much of the country, including Tennessee, beginning June 28, and lasting into next week.
The National Weather Service is anticipating temperatures in the 90s to low 100s.
“These hot temperatures combined with high humidity will lead to heat indices of 100-110 degrees and locally as high as 115,” wrote the weather service in a June 25 statement. “Low temperatures only dropping into the 70s will provide little overnight relief.”
Here’s what to know.
What is a heat dome?
Heat domes, also called ridges of high pressure or death ridges, are large bulges of sinking warm air that can stretch up to 1,000 miles in summer, driving temperatures 30 degrees above normal and creating hazardous, drying conditions that often lead to deadly, multi‑day heat waves, Weather.com said.
According to climatecheck.com, the term describes 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 said. “These large zones of hot air result in a combination of blistering temperatures, devastating wildfires, and drought conditions.”
How long will the heat dome last?
The period of extreme heat is expected to stretch through Independence Day weekend, lasting until July 6.
High to moderate extreme heat risk is expected across much of the central and eastern U.S. from July 3–4, with a broader slight risk extending through July 6. Heat indices of 100–110 degrees and warm nights in the 70s and 80s may limit relief over the holiday weekend, the weather service reported.
How hot will it get?
NOAA’s Weather Prediction Center said hot weather will be the story this coming weekend from the Plains to the Ohio Valley, with widespread above-average temperatures expected thanks to a strong upper-level ridge of high pressure (aka heat dome) developing.
Highs in the 90s are expected as far north as the Great Lakes and Minnesota, and 100s for much of Texas, USA TODAY reported.
Heat indices approaching 110 degrees are possible from the mid-South to the central Gulf Coast where the combination of heat and high dew points will be greatest.
Overnight lows will also be quite warm, with some record high minimums possible.
For much of next week, the core of the heat dome is likely to be centered on the Ohio Valley, the middle portion of the Mississippi Valley and the Tennessee Valley, according to AccuWeather. At times, the heat will expand outward and reach parts of the Plains, the Great Lakes, the East and the Gulf Coast.
How will the heat dome impact Tennessee?
According to the National Weather Service Nashville office, “oppressive” heat and humidity will bring triple digit heat indices from Sunday onward.
“Look for our rain chances to abate from Sunday onward, just as the first bonafide heat wave of the season settles in for the long haul,” wrote the weather service in its morning discussion June 26.
“While rain chances next week will be nearly non-existent, temperatures across the bulk of the mid state west of the Cumberland Plateau will top out in the mid to upper 90s every day at least through Friday.”
This will result in heat indices reaching the 100s across most areas, with heat advisory criteria likely to be met on multiple days, added the service.
All of Tennessee is expected to receive major heat, while portions of Middle Tennessee and all of West Tennessee will face extreme heat.
According to the weather service, major heat can affect anyone without proper cooling and hydration, as well as strain health systems and industries, while extreme heat involves rare and or prolonged high temperatures with little to no overnight relief, impacting anyone without adequate cooling or hydration.
How to stay safe during periods of high, dangerous heat
Extreme heat can lead to heat-related illnesses and even death.
According to the Centers for Disease Control and Prevention, heat-related illness occurs when the body is unable to properly cool itself. Older adults, young children and people with chronic medical conditions are at especially high risk.
The CDC reports that more than 700 people die from extreme heat each year in the United States.
The CDC recommends the following during periods of extreme heat:
- Stay in an air-conditioned indoor location as much as you can.
- Drink plenty of fluids even if you don’t feel thirsty.
- Schedule outdoor activities carefully and pace yourself. Wear loose, lightweight, light-colored clothing and sunscreen.
- Take cool showers or baths to cool down.
- Check on a friend or neighbor and have someone do the same for you.
- Never leave children or pets in cars.
- Check the local news for health and safety updates.
Contributing: USA TODAY
Diana Leyva covers trending news and service journalism for The Tennessean. Contact her at Dleyva@gannett.com.
