Credit: CC0 Public DomainAs bizarre as the deadly heat wave that hit the Pacific Northwest may seem, it fits in with a decade-long pattern of uneven summer heating across the United States.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 being 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 extreme heat for much of the week was caused by an unusual, but natural weather condition that occurred over the weekend, scientists now see the fingerprints of human-caused climate changes. They cite altered weather patterns that have allowed heat to accumulate 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.NOAA records indicate that the East is becoming wetter every decade. The East Coast is experiencing its greatest warming increase at night. Overnight lows in New Jersey, Delaware and Pennsylvania have increased by 3 degrees in the past 90 days, which is the largest increase in the country.Francis explained that water vapor is a greenhouse gaz. "So at night, it traps more heat."Kathie Dello is North Carolina's state climateologist. She attributes the changes to human-caused global warming. She stated, "There is no other explanation."She also said that, while extreme daytime temperatures can be alarming, warm nights can be deadly. She said that while it may not seem like a problem, warm nights can pose a risk to public health if there is insufficient cooling.It's becoming increasingly difficult to hide from the heat: "All my places for a quick getaway were absurdly hotOregon and North Carolina, even upstate New York?" What are the options? Canada isn’t secure."Continue exploring the West USA, where record heat waves are expected2021 The Associated Press. All rights reserved. Without permission, this material may not be broadcast, rewritten, or redistributed.
