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'Heat dome' scorches western US with record-breaking temps

The dramatic badlands of Zabriskie Point in Death Valley lit by the late afternoon sun.
The dramatic badlands of Zabriskie Point in Death Valley lit by the late afternoon sun. (Image credit: NPS / Kurt Moses)

Temperatures in Death Valley, California, hit a scorching 122 degrees Fahrenheit (50 degrees Celsius) Tuesday (June 15), short of the all-time record for this spot at the lowest elevation in North America but more than 10 degrees hotter than the average high temperature at this time of year.

The broiling temperatures were part of a broader heat wave across the American Southwest and West this week. On Tuesday, Denver reached a high of 101 F (38 C), the earliest in the year the temperature has topped 100 F (37.8 C) since 2013. The same day saw a sweltering 105 F (40.6 C) in Billings, Montana, a record for that date, and an all-time high of 107 F (41.7 C) in Sheridan, Wyoming, tying a previous state record. Salt Lake City also tied its highest temperature ever recorded, 107 F, on Tuesday. Southern California broke multiple heat records, with Palm Springs wilting under a high temperature of 119 F (48.3 C). Meanwhile, Phoenix, Arizona, tied its 1974 record temperature of 115 F (46.1 C).

Death Valley is known for its withering heat. The desert is situated below sea level but walled in by steep mountains, according to the National Park Service (NPS). Sunlight heats the dry desert floor, and the heat stays trapped by the surrounding rock and soil. The all-time highest air-temperature record in the world was set at Furnace Creek in Death Valley on July 10, 1913. On that day, Furnace Creek hit 134 F (57 C).

Related: Hell on Earth: Take a photo tour of Death Valley

Contributing to the current heat is a weather pattern known as a "heat dome." According to CNN, a ridge of high pressure over the western U.S. is trapping hot air close to the surface and also pushing away any potential precipitation. Sunny skies are also heating things up within the dome. And making matters worse, much of the West is currently in a deep drought

Drought means less moisture in the air and soil. When it's wetter, a significant fraction of solar energy goes to heating and evaporating this moisture, said Karen McKinnon, a climate scientist at the University of California, Los Angeles. In drier times, this wet "heat sink" is missing, so temperatures are free to soar.

"All of that heat is coming in, but the soils are so dry," McKinnon told Live Science. "So more of that heat is going to go into increasing temperatures instead of evaporating water."

Though Death Valley is no stranger to high temperatures, average temperatures in June are typically closer to 110 F (43.3 C) than to 120 F (48.9 C), according to the NPS. The average high temperature there in July is 116 F (46.7 C).

Temperatures in Death Valley through Friday are expected to match or exceed Tuesday's high. An excessive heat warning is in place for much of California and Arizona through Saturday.

Originally published on Live Science.

Stephanie Pappas

Stephanie Pappas is a contributing writer for Live Science covering topics from geoscience to archaeology to the human brain and behavior. A freelancer based in Denver, Colorado, she also regularly contributes to Scientific American and The Monitor, the monthly magazine of the American Psychological Association. Stephanie received a bachelor's degree in psychology from the University of South Carolina and a graduate certificate in science communication from the University of California, Santa Cruz.