chances for a white x-mas!

Will we have a white Christmas? It's an age-old question that occurs to almost everyone during the holiday season. 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.

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.

Table 1 presents city-by-city probabilities for at least 1, 5, and 10- inch depths on Christmas morning.
Table 1

Probability of snow depth on Christmas Day
greater than or equal to values (in inches)
shown at top of column

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1 Inch 5 Inches 6 Inches
AUGUSTA  90% 52% 21%
BRUNSWICK 80% 40% 17%
Caribou 97% 77% 57%
Houlton 96% 74% 52%
Portland 83% 43% 13%
Concord  87% 57% 7%
Lebanon 85% 70% 30%
Mount Washington 93% 63% 27%

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created 2/01
by E. Schwibs