A heat wave forecast for the US has alarmed scientists

A sustained gust of heat is expected to bake much of the United States in higher-than-normal temperatures this holiday weekend, and forecasts suggest the heat and humidity could persist for several weeks.

Extreme weather, the first major heat wave of the season, occurs when many states are struggling to contain the rampant spread of the coronavirus and resources are already depleted. And while the pandemic presents some unique challenges this summer, experts say these extreme events will continue to pose public health risks because climate change is making heat waves around the world more frequent and intense.

The coming heat is expected to affect large parts of the U.S., from eastern New Mexico and Colorado through the central plains and northeast.

“The first half of July appears to have much higher than normal temperatures, with fairly high probabilities, starting around July 4 or slightly earlier,” said Jon Gottschalck, head of the Operational Prediction Branch at the Climate Prediction Center of the National Metereological Service. .

Some places are already suffocated in record conditions. Miami recently had its hottest week on record and recorded its eleventh consecutive day with a heat index of over 103 degrees, Brian McNoldy, a senior research fellow at the University of Miami’s Rosenstiel School of Marine and Atmospheric Sciences, tweeted Thursday.

Gottschalck said that several regions are likely to be under heat warning and excessive heat monitoring, and said that warm conditions can persist at night, with little relief from humidity.

The heat is being driven by the northward displacement of the jet stream, which creates a “ridge effect,” a high-pressure pocket that allows for hot, dry surface conditions, Gottschalck said. The impending heat explosion could also create a “ring of fire” weather pattern, in which storms move along the periphery of the heat dome and trigger severe thunderstorms in the northern plains, he said.

Current forecasts show that this heat dome could remain throughout the month.

“Our models indicate that this will be somewhat persistent for the first two weeks of July and potentially longer,” Gottschalck said.

He said the Climate Prediction Center has been working closely with the Federal Emergency Management Agency and local agencies on how to handle heat waves and other extreme weather events during the pandemic.

Some cities, for example, may not be able to provide aid to vulnerable people due to patterns of social distancing.

“We are dealing with such a unique situation, where even if some areas can open cooling centers and the like, they are likely to have limited capacity,” said Julie Caron, a climate scientist at the National Center for Atmospheric Research. in Boulder, Colorado. “So now, you could have a vulnerable population that has to choose to stay home and risk the heat or go to a cooling center and expose themselves to the virus.”

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But even without the pandemic, he said, these events are troubling in the context of global warming.

“There is a long-term warming trend, but we are also seeing an increasing rate of change that is remarkable since 2015,” Caron said. “What that means is that we are getting hotter and more frequent heat waves on top of each other.”

The changes are magnified in the summer, particularly since July is typically when most parts of the contiguous United States have their hottest days of the year.

“You are exacerbating the extremes of heat in an already hot season,” Caron said. “That’s why it’s not just about heat waves, necessarily. It’s that we are seeing warmer than normal seasons.”