Fresno, California 2021-12-18 08:09:16 –
A 40-year analysis of US snow measurements on December 25 shows that fewer countries snow on Christmas than in the 1980s.
This is especially true for belts that cross the central part of the country hundreds of miles north of Baltimore in Denver. And the falling snow is not measured to the depth of the past.
Scientists say the decline in the number of White Christmas is relatively small, and they are careful to draw conclusions. But it stands out and is very important for some people like George Holland.
An educator known for the retired, nativity scene in the front yard of Iowa said Christmas snow is considered part of the holiday.
However, in recent years, the weather in Dubuque has not cooperated. “There is no white Christmas, not years,” said boutique owner Bill K’sbauer.
The last one was held in Dubuque in 2017. According to weather records, nearly two of the three years were White Christmas.
Average December temperatures in the continental United States were slightly below freezing between 1981 and 1990, federal weather records show. And from 2011 to 2020, it averaged slightly above 35 degrees Celsius (slightly below 2 degrees Celsius) and well above freezing.
But what did that warming trend, natural weather fluctuations, and western megadroughts mean for White Christmas?
From 1981 to 1990, on average, almost 47% of the country snowed on the ground on Christmas day, with an average depth of 3.5 inches (8.8 inches), according to an analysis of ground-based observations by the University of Arizona for the Associated Press. It was centimeters). push. From 2011 to 2020, Christmas snowfall decreased to 38%, with an average depth of 2.7 inches (6.8 centimeters).
This change was especially noticeable in the strips from the Mason-Dixon line to just north of Detroit, Chicago, and Nebraska. According to Arizona data, the average Christmas snowfall is just above 41% today, from nearly 55% in the 1980s. The average snow depth has decreased from 3.5 inches (8.8 centimeters) to 2.4 inches (6 centimeters).
Xubin Zeng, an atmospheric scientist at the University of Arizona who ran the data, asked if this was a meaningful trend because the numbers were small enough, and if so, whether it was due to climate change or natural weather change. It’s difficult to judge.
Nonetheless, Zeng, who published a study on the reduction of snow cover in the western United States associated with climate change, said the downward slide for White Christmas is consistent with global warming.
Mark Serreze, director of the National Snow and Ice Data Center in Boulder, Colorado, said: “With the climate warming, the outlook for White Christmas in many parts of the United States in 20 to 30 years will certainly be bleak. “.
Another analysis by the US National Oceanic and Atmospheric Administration examines “normal values” (30 years at approximately 5,000 meteorological stations in the 48 states of the continental United States). Comparing the 1981-2010 normals with the 1991-2020 normals shows that more stations are seeing the statistical odds of shrinking White Christmas, but the agency decides to conclude on the trend. I am warning you.
According to NOAA, in much of Iowa and eastern Washington, the changes are greater than elsewhere. From 1981 to 2010, Dubuque’s chances of a white Christmas were 63%, but now it’s down to 42%. Washington’s chances of having a White Christmas have halved from 19% in 1981-2010 to 9.5% now.
Denver airport stations have a 40% to 34% chance of snow for Christmas from 1981 to 2010. Chicago, St. Louis, Kansas City, Salt Lake City, Milwaukee, Fort Wayne, Topeka, Des Moines, Akron, Albany, Olympia, Rapid City and Oklahoma City airports saw a 3-4 percent decline.
Imke Durre, a NOAA climate scientist, said the line with at least a 10% chance of White Christmas has moved significantly north on the new normal. And the capital of the country went from 10% to 7%.
“The movement of the line is in line with the warmer December,” Durre said.
The Philadelphia New York and New Hampshire Concord recorded a slight increase in the likelihood of snow on the ground.
According to the Ratgers University Global Snow Lab dataset, satellite imagery data dates back to 1966, according to satellite imagery data, David Robinson, saying that snow in the Americas in the last week of December has increased slightly rather than decreased. Mr. says.
“There is no trend, you just don’t see it,” Robinson said.
People in the 1960s and 70s often think that the number of White Christmass is low, as there were more White Christmass than usual in the 1960s.
Temperature changes snowfall in two different ways. In warmer border areas, warmer air turns snow into rain. But in cooler northern regions where higher temperatures are still below freezing, warmer temperatures mean more snow, as warmer air retains more water and it comes down as snow. To do.
Some meteorologists have warned about finding trends in complex data where both precipitation and temperature are factors. However, despite these issues, the number of white Christmas associated with rising temperatures due to climate change seems to be small, said Victor Gensini, a professor of meteorology at Northern Illinois University.
“For many, it’s important as an emotional weight of how the season should feel, or how we should feel,” said Twila Moon, a national snow and ice data scientist. “But my climate scientists are very interested in White Christmas because it shows how much precipitation we have acquired, and much of our country. It’s also very important because it’s dealing with extreme droughts. Right now. “
In Helena, Montana, on Tuesday’s high hit 52 (11 degrees Celsius), “I feel like there isn’t much snow or winter is different,” said Shaun White. “Now, when I look out the window, the whole valley hill looks nice. It’s brown. It’s ugly and brown.
“For us here, we expect winter and cold, which makes you feel comfortable and cozy,” he said, struggling to get the spirit of a snow-free Christmas. Technical manager White said.
Maybe if she just went to Carol, it would be like a Hallmark movie, and Christmas snow would come at the last minute, she said.
Copyright © 2021 AP communication. all rights reserved.
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