Heated dome from coast to coast to provide sweltering weather next week (but not here)
Summer is supposed to be hot. But this season has been marked by numerous large-scale North American heatwaves that have ravaged significant parts of the country, helping temperatures soar and break records.
Another heat wave is expected to park on Lower 48 next week, bringing abnormal summer heat to parts of the central and eastern United States that may have missed previous events.
Early estimates indicate that most of the contiguous United States will see highs 10 to 15 degrees above average. When combined with increasing humidity, you’ll feel like it’s fine in the triple digits for millions. The model could also trigger severe thunderstorms, possibly strong winds, that could cross the northern Great Lakes and New England in late July and August.
Most of the heat on Thursday was relegated to the western United States, where temperatures in Montana are expected to climb into the 100’s.
Billings, Mont., Has already measured 12 days exceeding 95 degrees this month. With highs in the 90s above 100 below projected each day over the coming week, there is a possibility that the tally will climb to nearly 20 by the end of July. This would mark the most 95 degree-days in Billings in July since 1936.
Excessive heat warnings are in effect for much of eastern Montana, where temperatures could increase the risk of heat-related illnesses. Some relief is on the way – but not much.
“Tonight’s cold front will bring very modest ‘cooling’ for Friday, with highs tomorrow in the 90s,” the Weather Service wrote in Billings.
On Friday and Saturday, that heat will shift eastward, bringing highs in the 90s above nearly 100 in the Dakotas this weekend. It’s just an appetizer, however. The main heat episode, which will occupy more of the western and central United States, will only begin by then.
On Monday and Tuesday, attention turns to the Pacific Northwest and northern Intermountain West, where a new heat wave will begin to build up. This bundle represents the first signs of a building thermal dome that will drape over most of the lower 48 by the middle of the week.
On Wednesday, the thermal dome is expected to stretch from the Pacific coast to the Appalachians, with hazy and warm temperatures all over the place in between. The National Oceanic and Atmospheric Administration’s Climate Prediction Center reports near-average to above-average temperature probabilities for the entire contiguous United States.
It is too early to give exact numbers, but the plains could see temperatures in the 90s above or below 100 as the heat wave develops, with mid to upper 90s in the southeast and many areas exceeding 100 in the west.
Heated domes are areas of high pressure that provide descending air, which heats up and dries as it sags. A thermal dome can also help bring clear skies, while deflecting the clouds and storm systems around it. This allows additional sunshine, boosting the heating.
As the heated gases expand, in this case vertically, the “midway point” of the mass of the atmosphere could end up near a higher than average football field next week.
While almost everyone will bask in the warmth of the summer, a few areas will tend to get closer to average. Monsoon moisture at the start of the week can persist in the southwestern Desert and Four Corners region, keeping temperatures a bit more subdued as showers and thunderstorms brew in the afternoon.
Another area to watch out for that might not take full advantage of the heat will be parts of New England. Computer weather models suggest that a lobe of cool air can hang around at high altitudes, keeping surface temperatures closer to average. Between there and the heat dome, a corridor of stormy activity may appear; the configuration of the jet stream would favor strong winds.
The greatest risk of strong to severe storms during this period would come from the northern part and upper Midwest to the Great Lakes region and to the northeast.
While thermal domes are normal building blocks of summer, the duration and intensity of these heat events increase as global temperatures warm due to human-induced climate change.
Last month, a thousand-year-old heat episode that would have been “virtually impossible” without climate change brought temperatures of 108 degrees in Seattle and 116 degrees in Portland, Oregon. Lytton, British Columbia, broke Canada’s national temperature record three days in a row, reaching 122 degrees before the town burned down in a cataclysmic wildfire.
Meanwhile, much of the United States has spent days veiled by a blanket of wildfire smoke spilled into the skies by hundreds of fires across western North America, including the Bootleg 400,000 acre fire in southeastern Oregon. Climate change continues to accelerate the drought conditions that set in in the West, promoting more favorable fire conditions and more extreme forest fire behavior.