A widespread and dangerous heat wave was building across the U.S. on Saturday, with triple-digit highs expected in the Southwest and Great Plains this weekend before spreading eastward under a dome of high pressure that meteorologists say could trap oppressive temperatures for a week or more.
Forecasters advised people to stay hydrated and find places to cool off, warning of temperatures 15 to 25 degrees Fahrenheit (8 to 14 degrees Celsius) warmer
than normal in many areas, including at night — especially bad for people's health because their bodies won't have a chance to recover. The heat dome was expected to affect as much as two-thirds of the continental United States.
“The heat doesn’t necessarily stop when it’s dark out,” said Josh Adam, a meteorologist with the National Weather Service in Bismarck, North Dakota, where temperatures will surpass 100 F (37 C) until Tuesday, a dramatic spike for a state where summer temperatures are typically in the 80s.
Tynika Smith of Bloomington, Minnesota, handed out frozen towels and wash cloths along with battery-operated fans to people at encampments of homeless people in nearby St. Paul as the heat ramped up. The residents put the ice packs around their necks and on their heads.
“They can’t get into a car with air conditioning or go into a house,” said Smith, who also distributed water, freezer pops, food and hygiene supplies.
The encampments were so secluded that it was difficult for the residents to walk or bicycle to cooling centers, she said. There also was little outside shade, while the temperature inside their tents was even hotter than outdoors.
“I can only do so much,” Smith said, “but at least I can help them stay cool for a little bit.”
The National Weather Service predicted that more than 90 U.S. local temperature records will be tied or broken through Wednesday — with two-thirds of those being overnight heat records. Temperatures were not forecast to drop below 80 F (27 C) at night in Fort Lauderdale, Florida; Miami; Tampa, Florida; Galveston, Texas; and Charleston, South Carolina.
The heat dome — formed when high pressure traps hot air while blocking cooling winds and rain — is one of the strongest to affect the Dakotas in 25 years, said Chad Merrill, a senior meteorologist with AccuWeather.
Record triple-digit highs were forecast for the weekend in Nevada, Utah, Colorado, Wyoming, Idaho, Montana and the Dakotas.
In Helena, Montana, where temperatures were expected to creep above 95 F (35 C), Last Chance Splash Waterpark & Pool was holding a swim meet for hundreds of swimmers.
The timing couldn’t be better, as it’s uncommon for Helena to get so hot, said Sean Swingley, assistant manager.
“It’s certainly a hot day, but the pool is nice and cool,” Swingley said. “Usually in the summer we have a couple 95 degree days, but it mostly hovers around 85 to 90 in June and July.”
Nevada, a state accustomed to hot weather, was even hotter than normal, said Andrew Gorelow, a meteorologist with the National Weather Service in Las Vegas. The temperature there was expected to hit 111 F (48 C) on Saturday, Gorelow said.
Hydrating and finding cool spaces is critical, experts said.
They also warned that the heat could spike fire risk in some parts of the country that already are dry, including the Rockies, where Merrill said dry thunderstorms could develop.
Climate change from the burning of coal, oil and natural gas is causing more intense and longer-lasting heat waves that cover larger areas, scientists say.
This year's temperatures also are expected to be affected by El Nino, a natural warming of the equatorial Pacific that alters weather patterns and spikes temperatures across the globe.
The current El Nino — which formed last month and is too young to have affected this heat wave much — is expected to rank as among the most intense since the weather service began tracking the phenomena in 1950, experts said.
By fall it has an 81% chance of becoming “very strong” — the top category — according to the U.S. National Oceanic and Atmospheric Administration.
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