Introduction

Will we have a white Christmas? It's an age-old question that occurs to almost everyone this time of year. This report, created by the National Climatic Data Center (NCDC), contains maps and tables showing the percent probabilities for a snow depth of at least 1 inch on Christmas morning, as well as the probabilities for a depth of at least 5 inches and 10 inches. The "First Order" Summary of Day Dataset for the period of 1961-1990 was used to compute these statistics. Only stations with at least 25 years of data were used and the '61-'90 period was chosen to coincide with the standard period for computing climatological normals.

Discussion Following is a brief summary of our findings:

Greatest probability for at least 1-inch snow depth (continental U.S.):

100% -
Marquette MI
Sault Ste Marie MI
Hibbing MN
International Falls MN
Stampede Pass WA

Greatest probability for at least 5-inch snow depth (continental U.S.): 100% - Stampede Pass WA

Greatest probability for at least 10-inch snow depth (continental U.S.): 96% - Stampede Pass WA

Generally, the greatest probabilities lie where they would be expected-- over the northern U.S. and in mountainous areas. In defining a 'white Christmas' as having a snow depth of at least 1 inch, the chances are 60% or better over an area including much of the northern Rockies, the northern Great Plains, the Great Lakes area, and most of New England. The chances are less than 20% over most of the southern third of the country excluding the Rockies, along with the Pacific coast.

The 5 and 10-inch maps (Figures 3-6) indicate areas where there is a greater likelihood of encountering travel problems due to heavy snow. However, keep in mind that this is based on snow depth and not necessarily on newly fallen snow. Also, it is important to remember that higher mountain areas (e.g., elevation of 8000 feet in an area averaging about 4000 feet) will tend to have higher probabilities for each of the 3 categories.

The original source of this report can found on the NCDC web site at:
http://ols.nndc.noaa.gov/plolstore/plsql/olstore.prodspecific?prodnum=C00493-PUB-A0001

Additional NCDC information is also available at:
http://www.ncdc.noaa.gov/oa/climate/extremes/christmas.html