It’s excruciatingly hot in North Texas, and a weather phenomenon called a “heat dome” is to blame.
A heat dome has hovered over a massive part of the country creating dangerous temperatures in Texas, Oklahoma and Louisiana — and expanding as far as Arkansas, Kansas, Missouri, Mississippi and Florida in recent days.
“The reason why we’re having all this is heat is an area of high pressure directly over the central and southern United States,” Allison Prater, a meteorologist with the National Weather Service in Fort Worth, told The Dallas Morning News. “There’s been quite a bit of heat going out, and when we have that high pressure we have sinking air — so warming temperatures, not a lot of clouds and no rain chances.”
A trough — an elongated area of relatively low pressure — on the West Coast could make its way east to Texas in the latter half of the week and take the high pressure hovering over our region with it, Prater said.
“It looks like as that moves across the region into the Central Plains and toward the east that it’s going to break down the ridge of high pressure, giving us some lower temperatures,” she said. “It’s still going to be hot, but not nearly as hot as what we’ve been seeing.”
Those lower temperatures will be evident this weekend and early next week as chances for isolated storms in North Texas also increase. Heat indices will remain high, though, Prater said, so it’s important to continue practicing heat safety.
What is a heat dome?
Record high temperatures — or very hot heat waves — can happen because of a heat dome that parks itself over a specific spot, according to AccuWeather.
A heat dome occurs when a high-pressure system is “stuck” in a certain location and holds the heat in. The atmosphere acts like a lid or cap over a region and traps in the hot ocean air, according to the National Oceanic and Atmospheric Administration.
Heat domes usually are linked to the behavior of the jet stream, a band of fast-moving atmospheric winds that generally flow west to east, William Gallus, professor of atmospheric science at Iowa State University, wrote for CBS News.
The jet stream typically meanders north, south and north again, and larger northern and southern movements make the winds move more slowly. When that slow-moving wind grinds to a halt, a heat dome occurs. The warm air sinks, which clears the skies, lowers the humidity and creates conditions for the sun to bake everything beneath it.
“A heat dome can have serious impacts on people, because the stagnant weather pattern that allows it to exist usually results in weak winds and an increase in humidity,” Gallus wrote. “Both factors make the heat feel worse — and become more dangerous — because the human body is not cooled as much by sweating.”
When a heat dome settles into a location, it takes a big push from the jet stream or another relatively strong system higher up in the atmosphere to dislodge it and release the heat.
Is this the same thing as a heat wave?
A heat dome and a heat wave are not the same thing, but they can occur simultaneously.
A heat wave is a period, typically longer than two days, of abnormally hot weather, according to the National Weather Service. Like heat domes, heat waves have the potential to cover a large region and expose a high number of people to hazardous heat.
Dallas and surrounding North Texas areas have experienced both a heat wave and heat dome this week since temperatures first broke triple digits on Sunday. Cooler weather is expected in the coming days and possible storms are in the forecast this weekend ahead of July Fourth.
