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A cold spell with record-breaking negative values has large parts of the USA firmly under control and has already cost several people their lives. On Thursday night, extreme temperatures of up to minus 34 degrees Celsius were measured, especially in the so-called Midwest. The wind chill factor plays a role here.
Strong winds make the perceived temperature appear even colder than it already is. In the USA, the perceived temperatures are referred to as wind chill values. The wind chill factor plays a big role “How warm do I dress?” – so it’s about the temperatures.
It describes the cooling of the skin when the wind speed increases. The arctic winter club reached into the northeast of the country. In metropolises like New York and Philadelphia, squalls drove the snow through the air and clouded the view again and again.
At the weekend, however, the Americans have to demonstrate a strong cycle: Then the temperatures in many places should climb by more than 30 degrees Celsius and reach almost 20 degrees Celsius plus.
The American Midwest includes Illinois, Indiana, Iowa, Kansas, Michigan, Minnesota, Missouri, Nebraska, North Dakota, Ohio, South Dakota and Wisconsin. Chicago, on Lake Michigan in the north of the United States, was at the center of the great cold.
At least 30 people in the state have been treated in emergency rooms for hypothermia or chilblains, according to the Illinois Department of Health. The authorities set up more than 60 warm rooms for the homeless. In addition, every police station took in people who wanted to protect themselves from the cold.
In the metropolis in the state of Illinois, temperatures of minus 27 degrees Celsius were measured early Thursday morning. It was even more icy in the city of Rockford: there was sometimes minus 34 degrees Celsius in the morning, a new record for the place.
The rail company Amtrak canceled all train services to and from Chicago on Wednesday. In the city, the local transport operators started fire on some tracks, as the broadcaster CNN reported. In the extreme cold, the metal contracts, which causes the rail parts to separate from each other. The heat from the fire should expand the metal again so damage could be repaired.
In view of the brutal frost, even the weather-tested deliverers of the US postal service have to surrender in many places. The USPS said the service will be discontinued in Iowa, Minnesota, and parts of Wisconsin and Illinois.
The US Weather Service warned of frostbite on unprotected skin within minutes. The so-called polar vortex is responsible for this “arctic cold”. According to the German Weather Service (DWD), this air flow is actually not at all unusual. Because the eddy regularly forms at the pole when no sun penetrates through the arctic night in winter, which could warm the accumulated cold air. The resulting so-called high altitude low can generate strong westerly winds in the northern hemisphere.
But while the polar vortex normally remains stable with its center over the Arctic, it has now spread unusually far south. According to DWD spokesman Gerhard Lux, the special geographical conditions in North America also contribute to this: the Rocky Mountains, which run from north to south, repeatedly form a kind of guard rail.
