White Christmas seems to be slowly transforming from a sure-fire reality to a dream of snowy holidays that have passed for large swaths of the United States in recent decades.
An analysis of 40-year snow measurements on December 25 in the United States shows that the country now has less snow at Christmas than it did in the 1980s.
This is especially true for the belt that runs through the middle of the country, from Baltimore to Denver and several hundred miles further north. And the snow that has fallen does not reach the past depth.
Scientists say that the number of white Christmas holidays is declining relatively little, and are cautious in drawing conclusions. But it’s noticeable and very important to some people like George Holland.
Dabyuk, a retired Iowa educator known for his front-door nativity scenes, said snow at Christmas should be part of the holiday: “The one that warms my heart is after midnight mass and going outside and it’s snowing.”
But the weather in Dubuque in recent years has not been conducive to development. “We don’t have a white Christmas,” said boutique owner Bill Kesbauer. “We haven’t had anything in years.”
The latest was in 2017 in Dubuque, where weather data show that white Christmas holidays have been celebrated for almost two out of three years.
The average December temperature in the continental United States from 1981 to 1990 was just below freezing, as indicated by federal meteorological records. And from 2011 to 2020, it was on average just above 35 degrees (slightly less than 2 degrees Celsius), which is well above the freezing mark.
But what did this warming trend, natural weather variability and western mega-drought mean for the White Christmas?
From 1981 to 1990, an average of almost 47% of the country had snow on the ground with an average depth of 3.5 inches (8.8 centimeters), according to an analysis of ground-based observations conducted by the University of Arizona for the Associated Press. Click. From 2011 to 2020, Christmas snow cover decreased to 38% from an average thickness of 2.7 inches (6.8 centimeters).
This change was particularly noticeable on the Mason-Dixon line north of Detroit, Chicago and Nebraska. According to Arizona data, average snow cover over Christmas there has grown from nearly 55% in the 1980s to just over 41% now. Average snow depth has dropped from 3.5 inches (8.8 centimeters) to 2.4 inches (6 centimeters).
The numbers are so small that it’s hard to tell if this is a significant trend, and if so, it is climate change or natural weather variability, said Xubin Zeng, atmospheric scientist at the University of Arizona, who processed the data.
However, Zeng, who has published research on climate change-related snowfalls in the western US, said the slide down of white Christmas holidays is consistent with global warming.
In 20 to 30 years, “with a warming climate, the prospects for a white Christmas in many parts of the United States will really be slim,” said Mark Serrez, director of the National Snow and Ice Data Center in Boulder, Colorado.
A separate analysis by the National Oceanic and Atmospheric Administration considers “climate normals” – 30-year periods for about 5,000 weather stations in the lower 48 states. Comparing rates for 1981-2010 with rates for 1991-2020 shows that more stations see a statistical chance of a reduction in White Christmas, but the agency cautions against drawing any trend.
Most of Iowa and eastern Washington are changing more than anywhere else, according to NOAA. From 1981 to 2010, Dubuc’s chance of a white Christmas was 63%, but now it has dropped to 42%. Walla Walla, Washington’s chance of getting a white Christmas has dropped by half from 19% in 1981 to 2010 to 9.5% now.
The chance of Christmas snow falling at the Denver airport station from 1981 to 2010 dropped from 40% to 34%. Airports in Chicago, St. Louis, Kansas City, Salt Lake City, Milwaukee, Fort Wayne, Topeka, Des Moines, Akron, Albany, Olympia, Rapid City and Oklahoma City fell three or four percent item.
According to NOAA climatologist Imke Durre, the line where the probability of a white Christmas is at least 10% has shifted markedly north with new norms. And the country’s capital increased from 10% to 7%.
“The movement of this line corresponds to a warmer December,” said Darre.
In New York, Philadelphia and Concord, New Hampshire, there was a slight increase in the likelihood of Christmas snow falling on the ground.
A dataset from the Rutgers University Global Snow Laboratory shows that snow cover on the continental United States increased slightly in the last week of December, rather than decreased, said climatologist David Robinson, whose data, based on satellite imagery, date back to 1966.
“There is no trend. You just don’t see it, ”Robinson said.
He added that often people between the ages of 60 and 70 think that there are fewer white Christmas holidays because there were more than usual in the 60s.
Temperature affects snowfall in two different ways. In warmer border regions, warmer air turns snow into rain. But in cooler northern regions, where even warmer temperatures are still below freezing, warmer temperatures mean more snow because warmer air contains more moisture, which meteorologists say falls as snow.
Several meteorologists have warned against identifying trends in complex data in which both precipitation and temperature are factors. But despite these challenges, fewer white Christmas times appear to be associated with warmer temperatures as a result of climate change, said Victor Jensini, professor of meteorology at Northern Illinois University.
“For many, the emotional load of how the season should feel or how we think it should feel is important,” said Twila Moon, a scientist at National Snow and Ice Data. “But the climate scientist in me is also very interested in a white Christmas because it is an indication of how much and what type of rainfall we received. And this is also really important, because now most of our country is suffering from severe drought. “
In Helena, Montana, “it definitely feels like we don’t have much snow or the winter is different,” Shaun White said Tuesday, hitting 52 (11 Celsius). “I’m looking out my window right now, and I have a great view of the entire hill in the valley, and it’s brown. He’s ugly and brown.
“We expect winter and cold here, and it makes you feel cozy and cozy,” said White, an information technology manager, who said she was having trouble finding her Christmas spirit without snow.
Maybe, she said, if she just went caroling it would be like a movie and the Christmas snow would fall at the last minute.
This story has been corrected to show that the last white Christmas in Dubuque was in 2017 and not 2010.
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