CHICAGO — A hefty ridge of high pressure is expected to bring intense heat to many of the lower 48 states as we close out July.
Meteorologists expect a phenomenon similar to what caused deadly triple-digit temperatures in the Pacific Northwest last month to begin forming near the same region again as early as Monday. But the so-called heat dome won’t stay put over Portland and Seattle as the week continues.
“Most of the US mainland will be under this huge heat dome of high pressure,” says Meteorologist Gerard Jebaily of NewsNation. “Meteorologists unaffectionately call it a Ridge of Death. It won’t rain fire and brimstone or anything. It gets its name because the sinking air underneath the high-pressure dome suppresses shower and thunderstorm activity and the air becomes hot and stagnant.”
Full forecast analysis from our WGN Weather Center team at the Weather Center Blog.
A heat dome often forms when the jet stream is not strong enough to push weather across the continent, allowing high pressure to sit over one area where the warm air gets a chance to sink to the surface. Unlike last month’s scorching heat, this dome is expected to hit the middle of the country hardest.
“The worst-hit areas will be the central Plains from the Dakotas all the way to Texas, but the heat dome will partially sit over Pacific Northwest and possibly slide closer to the area,” said Jebaily.
The National Oceanic and Atmospheric Administration’s temperature outlook for the end of June shows high likelihood of above-average temperature for the entire continental United States outside of Arizona and the Northeast.
Pennsylvania State University climate scientist Michael Mann recently told the Associated Press that the number of times the jet stream stalls in the Northern Hemisphere is increasing from about six times a summer in the early 1980s to about eight times a summer now.
“We’ve shown climate change is making these stuck summer jet stream patterns more common,” Mann told the AP.
NOAA has warned that continued high temps will deepen drought concerns in the West.
AP reporting on National Interagency Fire Center figures shows that from 2011 to 2020, on average 7.5 million acres burned in wildfires each year. That’s more than double the average of 3.6 million acres a year from 1991 to 2000.
“This would worsen the already very active wildfire season as temperatures soar back toward 105 to 108 degrees. Desperately needed rain will also continue to be scarce causing already difficult firefighting conditions to become unbearable,” cautioned Jebaily, who said it more simply on Twitter, “The west just can’t catch a break.”
NOAA’s longer-term projections show a pattern or warmth and dry skies likely to persist over the next three months.