“So climate change is impacting tropical cyclone activity through modulation of sea surface temperatures, and also things like wind shear.” Ĭlimate change is making the heat wave more severe.īaseline temperatures were already higher than in the past, due to Earth’s changing climate. High-pressure systems like the one driving the Pacific Northwest heat wave is “something like three times more likely to occur when we have a tropical cyclone out in the Pacific,” he said. And like hurricanes, they are strengthened by warmer ocean temperatures. Those are the West Coast equivalent of hurricanes. One of the mechanisms for the formation of a high-pressure system is tropical cyclone activity in the western Pacific Ocean, he said. In Multnomah County, where Portland sits, “the projected change, by the middle of the century … is an additional 20 days (per year) with temperatures above 90 degrees,” he said. “By 2020, that number is at about 20 days per year,” O’Neill said. In 1940, he said, Portland had only about 10 days per year when the daily high temperature topped 90 F. In addition, the number of extreme heat days has doubled in less than a century, and it likely won’t stop at that, said Larry O’Neill, Oregon’s state climatologist. The Pacific Northwest’s average temperature has warmed more than 2 F compared with a century ago, with most of that change in the last 40 years. The sweltering weather, expected to cool slightly tomorrow, appears to be part of a broader climate change trend. We’ve never in anybody’s lifetimes seen anything quite like this before in Seattle.” “We’ve only had three days of 100 or more degrees in 126 years, and it looks like we’re ready to get three of them in a row now. “We’ve never seen anything like this before,” said Dustin Guy, a meteorologist with NWS’s office in Seattle. Pro: Climate change is expected to make this rare 1-in-1,000-year event more common
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