In a significant shift in weather patterns, meteorologists from AccuWeather have issued a warning about the development of a massive heat dome over the Heartland of the United States.

The heat dome is projected to linger through much of the second half of August. And it  is anticipated to bring scorching temperatures and dry conditions to various areas of the nation's midsection. 

While this heat wave is poised to cause discomfort in many regions, there is also a glimmer of relief on the horizon for parts of the South and West as the atmospheric setup shifts.

Heat Waves on the Rise

Last year the United States Environmental Protection Agency (EPA) put out a report detailing that, heat waves have been growing more frequent in major cities across the United States. And are occurring approximately six times a year on average.

 The oppressive heat experienced in July has been particularly noteworthy, shattering over 2,750 temperature records across the country in just the past 45 days.

Texas, in particular, has been bearing the brunt of this relentless heat, with cities such as Dallas, Austin, San Antonio, and Houston experiencing temperatures consistently 3 to 5 degrees above historical averages since the beginning of meteorological summer on June 1.

Houston had triple-digit temperatures throughout this month, with only a single exception on August 3 when the high reached 99 degrees.

These sweltering conditions starkly contrast with the historical average high of 94 degrees for the city, which is located near the northwest Gulf Coast. 

The Texas city has also seen a notable decrease in nights when temperatures dipped below 80 degrees, a departure from the historical average low temperature in the mid-70s.

"The same type of weather system that has been responsible for relentless heat in Texas and the South-Central states, as well as the interior Southwest much of this summer will regroup and set up shop farther north starting late this week," AccuWeather Senior Meteorologist Adam Douty said.

Understanding the Heat Dome

The concept of a heat dome involves a zone of high atmospheric pressure extending from the Earth's surface to the level at which jets fly. 

Once established, this phenomenon can trigger a self-perpetuating cycle of escalating heat and dryness that is challenging to break. 

The heat dome acts like a pressure lid, trapping hot air beneath it and facilitating the formation of heatwaves marked by temperatures significantly higher than the norm.

The mechanism behind a heat dome involves hot air expanding vertically into the atmosphere. The pressure from above confines this warm air, pushing it downward.

 As the warm air sinks, it compresses and further heats up, intensifying the heat buildup. This process leads to increased ground temperatures and decreased moisture levels, creating conditions ripe for wildfires. 

The high-pressure system of the dome influences cloud movement, further contributing to the heat retention.

Widespread Impact

While Texas has been the epicenter of extreme heat this summer, its effects have rippled across the country, reaching as far east as Florida and as far west as interior Southern California. 

The central and northern Plains, along with parts of the Midwest, are poised to experience the most sweltering temperatures of 2023 as the heat surge intensifies over the upcoming weekend and into the following week.

For instance, Des Moines, Iowa, witnessed its highest temperature of the summer at 98 degrees on July 28. Meteorologists predict that temperatures may surpass the 100-degree mark in the city for a few days in the early part of the coming week. 

Although some regions may not experience the hottest weather of the season so far, they are still expected to endure extreme heat. High temperatures near or slightly above 100 degrees are anticipated in cities such as Omaha, Nebraska; Kansas City, Missouri; St. Louis; and Topeka, Kansas.

The swift temperature increase contributes to the ongoing drought plaguing the central United States. Sections of Kansas, Nebraska, Missouri, Iowa, Minnesota, and Wisconsin are grappling with severe drought conditions, as per the United States Drought Monitor. 

The parched ground heats up faster than moist soil due to the reduced energy absorption caused by the evaporation of moisture.

"On the rim of the massive heat dome, moisture and cooler air will be found," Douty said. "These fringe areas will include the Gulf Coast, the western third of the nation, and the Northeast."

"Not only may these grab moisture from the Gulf, but one or more could also develop tropically," Douty added. "It would not be out of the question for a tropical depression or storm to brew over the western and northern part of the Gulf and move into Texas with heavy rain next week."