Historical probability of at least 1 inch of snow on the ground on Christmas. (NOAA)
As Christmas gets closer everyone always wonders if we are going to get the proverbial white Christmas. Unfortunately, if you look at Denver and Thornton weather history, the chances aren’t all that good but it also depends on what you define as a white Christmas.
If to you a white Christmas means having actual snowfall on Christmas Day the chances are pretty poor. But, if simply having snow on the ground suffices, the chances improve considerably.
As Christmas gets closer everyone always wonders if we are going to get the proverbial white Christmas. Unfortunately, if you look at Denver and Thornton weather history, the chances aren’t all that good but it also depends on what you define as a white Christmas.
If to you a white Christmas means having actual snowfall on Christmas Day the chances aren’t that good. But, if simply having snow on the ground suffices, the chances improve considerably.
White Christmas probability map for the contiguous United States. Click for larger view. (NOAA)
With our most recent snowstorm, the Colorado Front Range is likely to enjoy a white Christmas (defined as 1 inch of snow on the ground on Christmas Day). Other locations in the United States of course are not quite so lucky and historically, Colorado can be quite hit or miss.
Below is the latest narrative from NOAA. To the right is a probability map – click it to view full size.
Minnesota. Maine. Upstate New York. The Allegheny Mountains of Pennsylvania and West Virginia. Practically anywhere in Idaho. And of course, the Rockies or the Sierra Nevada Mountains. These are the places where weather history suggests you want to be if you’re looking for the best chance of a white Christmas.
The map at right shows the historic probability of there being at least 1-inch of snow on the ground in the Lower 48 states on December 25 based on the latest (1981-2010) U.S. Climate Normals from NOAA’s National Climatic Data Center. Dark gray shows places where the probability is less than 10 percent, while white shows probabilities greater than 90 percent.
The 1981–2010 Climate Normals are the latest three-decade averages of several climatological measurements. This dataset contains daily and monthly Normals of temperature, precipitation, snowfall, heating and cooling degree days, frost/freeze dates, and growing degree days calculated from observations at approximately 9,800 stations operated by NOAA’s National Weather Service.
While the map shows the climatological probability that a snow depth of at least one inch will be observed on December 25, the actual conditions this year may vary widely from these probabilities because the weather patterns present will determine the snow on the ground or snowfall on Christmas day. These probabilities are useful as a guide only to show where snow on the ground is more likely. For prediction of your actual weather on Christmas Day, check out your local forecast at Weather.gov.
You can locate Normals data for the observing station closest to you using the NCDC’sinteractive map.
If you would like to keep track of the snowfall across the United States on a daily basis, see the National Operational Hydrologic Remote Sensing Center’s National Snow Analyses. For a more detailed assessment of the probability of a white Christmas as well as documentation of the methodology used to calculate the map’s underlying climatological statistics, see the scientific paper, White Christmas? An Application of NOAA’s 1981-2010 Daily Normals, by NCEI scientists and published in the Bulletin of the American Meteorological Society. You can also download a spreadsheet to see the full list of stations and their historic probabilities.
This post was adapted from an article first published by the National Climatic Data Center. It was first published on December 11, 2013, and is reviewed each year and updated as needed.
For many the holiday season isn’t complete without a chill in the air and snow on the ground. Here in Denver we historically enjoy a better chance of experiencing the proverbial white Christmas than many places in the nation.
How the Mile High City fares in experiencing a white Christmas does depend on your definition of one. If it means having actual snowfall on Christmas Day the chances aren’t that good. However if simply having snow on the ground suffices, the chances improve considerably.
Old Man Winter brought a white Christmas to much of the northern half of the United States which may be a blessing or a curse depending on your point of view. Images released by the National Operational Hydrologic Remote Sensing Center show that many areas that wouldn’t normally expect snow are covered in a blanket of white this Christmas.
Much of the country west of the Continental Divide will have snow or rain Christmas Day. Areas of the Sierra Nevada and southwestern Colorado will be measuring the snow in feet. Salt Lake City is expecting 4 to 8 inches while here in Denver we remain dry and will actually have a pretty mild day.
In the northeast they will have a cold and blustery holiday. Lake Erie and Lake Ontario will generate some lake-effect snows from Pennsylvania through New York and into northern New England.
The latest cold blast to hit the nation has caused travel woes across much of it. In Chicago, 500 flights were canceled on Tuesday stranding many travelers, some of whom won’t be able to reach their destination until today. 100 flights were canceled at O’Hare Wednesday but delays improved as the day went on. Sadly the weather did have a more serious toll as between Tuesday and Wednesday at least 30 people were killed in crashes on rain- and ice-slickened roads across the nation’s midsection.
Out west in Washington and Oregon, residents and government officials were wishing for a return to their normal rainy weather as they were unprepared for the snow that has fallen in recent days. In Portland, Oregon many side streets were impassable without chains or four wheel drive. Wednesday more snow fell followed by rain which most likely will add to the problems when it freezes tonight.
Washington Governor Chris Gregoire declared a statewide winter storm emergency saying, “A number of counties and cities are struggling to meet the problems posed by this month’s onslaught of snow and winter weather. Snowfall has reached record or near-record level in 30 of the state’s 39 counties.” Her proclamation will allow state agencies to support local operations including the activation of the National Guard.
Here in Colorado, much of the western slope is under various types of winter weather advisories. A Winter Storm Warning covers the western half of the state and Blizzard and Avalanche Warnings cover some areas south of I-70. Needless to say, Christmas Day travel in the high country will be greatly impeded by these storms.
Good weather along the eastern part of Colorado has allowed Denver International Airport to operate normally for the most part. However, some delays were experienced for flights heading to other parts of the nation affected by the winter weather.
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Here in Colorado, much of the western slope is under