Thermometer
© Johnysweb/flickr/cc

A massive "heat dome" is heading for the U.S. that will bake much of the country to potentially record-breaking temperatures next week, the Washington Post reports.

Only the Pacific Northwest is expected to escape the heat wave, while the rest of the country can look forward to some of its "hottest weather with respect to normal," the Post's weather editor Jason Samenow writes.

Although it is too early to know exactly how hot it will get, temperatures in the central U.S. and Upper Midwest could reach 10 to 20 degrees above average. Highs in Des Moines, Iowa, for example, may surpass 100°F for three days straight.

According to Atlas Obscura, heat domes are a "meteorological phenomenon" that occur when "a high-pressure system forms in the mid- to upper-atmosphere; the air pressure pushes warm air down towards the surface and traps it there, resulting in higher—often much higher—than normal temperatures."

The phrase came into popular use around 2011, although Oklahoma-based meteorologist Gary England told the New York Times that the title was "a little bit misleading" and that the phenomenon would be more accurately described as a "heat bubble."

Bubble or dome, it's coming. As Mashable's science editor Andrew Freedman points out, "Both the European and GFS models, among others, are depicting the height of the 500 millibar pressure surface, which is normally located around 5,000 meters, or 18,000 feet, to be at or above 6,000 meters, or 19,685 feet.

There are other concerns. Freedman writes:
Another hazard may also be found along the northern fringe of the heat dome, from southern Canada across the northern Great Lakes states and into New England. Atmospheric disturbances tend to ripple across the outer edges of such weather patterns, triggering large complexes of severe thunderstorms.

[....] One of the most confident conclusions in climate science is that heat waves are becoming more intense and more common as the world warms in response to increasing amounts of greenhouse gases in the air.
The heat wave comes as global temperatures continue to break previous records. In May, the National Oceanic and Atmospheric Administration (NOAA) released its annual State of the Climate report which found that April 2016 marked the 12th consecutive warmest month on record.

And as Atlas Obscura warns, "As with many other extreme weather events around the world, climate change may be making heat domes more common than ever."