A shot of truly polar air moved into the Lower 48 this week, sending temperatures plummeting. Of course, what is considered extreme cold today is not as cold as winters in previous decades. The latest cold shot brought some of the most teeth-chattering temperatures to the Dakotas and Minnesota. But as seen in the chart below comparing observedMore
As the calendar works toward Christmas Day, an annual question returns, “will there be a White Christmas?”
In some parts of the U.S., a white Christmas is expected, while in others, it is unheard of. The white areas on the map below indicate the historical chances of a white Christmas, based on the National Centers for Environmental Information climate data from 1981-2010. In this case, a white Christmas is defined as having one inch of snow on the ground on Christmas Day.
In the West, the odds of a white Christmas follow topography. Narrow strips of white along the West Coast indicate the high historical probability of snow on the ground in the Cascades and the Sierras, as does the wider swath of white covering the Rockies and other mountain ranges. Northern locations such as Minnesota, Wisconsin, Maine and upstate New York also usually have snow on the ground on Dec. 25. In contrast, the Southeast usually sees nary a flake.
A look at the current snow cover map in the U.S. is actually pretty similar to the historical probability map, with snow (or no snow) in most locations you would expect for this time of year. There are some subtle differences, however, with snow currently covering most of the Dakotas, Michigan, and New York, areas that are usually far from guaranteed to have a white Christmas.
This weekend, a large storm system will move from the Rockies to the Northern Plains, likely bringing fresh snow on Christmas Day to an area from Colorado to Minnesota before racing into southern Canada. However, a surge of warm air will precede it, likely melting any remaining snow in Iowa, Illinois, Ohio and Pennsylvania.
And it will be far too warm for snow in the Southeast on Christmas Day this year.
Climate change could wash out white Christmas in areas where they’re already unlikely. Rising temperatures are ensuring that more winter precipitation is falling as rain in many locations across the U.S.
A Climate Central analysis of 65 years of winter precipitation data from more than 2,000 weather stations in 42 states, found a decrease in the percent of precipitation falling as snow in winter months for every region of the country.
For much of the country, winter is the fastest warming of the four seasons, with the coldest states warming the most. Since 1912, states with average winter temperatures below 32°F have warmed three times faster than states with average temperatures above 32°F. And during that time, winter nights in the coldest states warmed up to five times faster than those in warm states.
That means that while white Christmases will not disappear in the near future, it is likely they will become less common in places that have become accustomed to them in years past.