An analysis of decades worth of U.S. summer weather data from The Associated Press shows that the West is being roasted by warmer summer days, while the East Coast is getting swamped with hotter and stickier nights.
The average state-by-state temperature trends for 1990-2020 show that America's summer heat is rising in places like California, Nevada and New Mexico.
The West is the most rapidly-warming area in the country, with average temperatures rising by 3 degrees per year since 1990. In the last 30 years, the Northwest has experienced nearly twice the temperature increase as the Southeast.
Portland, Oregon was the first to set a new record at 116 degrees. This was 3 degrees higher than any temperature ever recorded in Oklahoma City and Dallas-Fort Worth.
Although most of the primary causes of this week's extreme heat were unusual, but not natural, scientists believe that humans are responsible for climate change. They see altered weather patterns, which park heat in different locations for longer periods of time.
According to Judah Cohen, a meteorologist at the private firm Atmospheric and Environmental Research, "The absurd temperatures in the Pacific Northwest can be seen as a black Swan (ultrarare) event but they are consistent with long-term trends." While I cannot predict when Portland will reach 116 again, I do believe that hotter summers are on the horizon for the greater region.
Climate change is changing and weakening jet stream, the narrow bands of wind that circle Earth moving west to east. These changes cause key weather-producing patterns such as high and low pressure to stall. According to Michael Mann, a climate scientist at Pennsylvania State University, high pressure is stalling in the West more often during summer. High pressure can cause hot, dry weather, which, when it stalls, can lead to heat domes. Wet weather is caused by low pressure.
Another factor is the higher temperatures in the Pacific Ocean, which also create more high-pressure Ridges the West, according to Gerald Meehl (National Center for Atmospheric Research scientist, who studies heat waves).
These patterns are so common that long-term data can show their effects. Cohen stated that the U.S. Northwest and western Canada, as well as Siberia, have been experiencing some of the fastest warming areas on Earth since 1990.
The summer heat in the Midwest is slower than on the coast. Victor Gensini, a North Illinois University climate scientist, explained that cooler air is often drawn into the Great Lakes region by low pressure areas that have stalled.
Scientists believe that water is the reason for the large difference in eastern and western heat trends.
"Soil moisture has been decreasing in western states, where drought has been increasing and intensifying over the past decade." Because all of the sun's energy is used to heat the soil, dry soil heats up more quickly than moist soil during daylight," Jennifer Francis, a Woodwell Climate Research Centre climate scientist, said. Dry soil also cools down faster at night."
This is partly why the West is experiencing crazy triple-digit daytime temperatures, despite being getting drier every decade.