What are the chances of a White Christmas across eastern North Dakota and northwest through west central Minnesota in any given year? The graphic below shows that most of our area has a greater than 75 percent chance of a White Christmas with a 90 percent or better chance for most of northwest Minnesota. But what are the odds of a Brown Christmas, that is a trace of snow or less, on the ground Christmas Morning? The answer may surprise folks.
The image above is courtesy of the National Climate Data Center based on the updated 1981 - 2010 normals. Click here for the previous version.
The table below shows some interesting information on two locations in our region for the past 68 winters (1942-2010).
First, lets define what exactly we mean by a "Brown Christmas". The official snow measurement for the climatological day is taken at 6 am CST. This has been the standard practice since the early days of weather observing. For example, the last Brown Christmas (less than 1 inch of snow-depth) for the UND/NWS site listed in 2011, indicating that at 6am on December 25th 2006 the NWS Observer recorded a trace of snow at the official observation location. We did finally get snow three days later, which then lasted through March.
Based on the updated climatology produced by the National Climate Data Center, there has a shift - a very slight shift - to lower probabilities of a White Christmas the past 30 years.
The latest 1 inch snowfall for the Fargo area was on January 27 1944*; for the UND/NWS Climate station it was January 13 1953*. Just 3 years ago, the first snowfall [which remained on the ground] at the UND/NWS location was not until December 1st and for Fargo it was December 2nd. Looking at the long term record, it is not unusual to be well into December before snow accumulates. Over the past 110 years, the first 1 inch of snow in Fargo did not fall until after December 1st twenty three times; for UND/NWS it was thirteen times.
Looking more closely at the data from the Fargo Airport, the last time the Christmas Morning snow depth was zero -not even a trace listed- was 2006; previous years include 1957 and 1943. For the UND/NWS site, the last time the ground was listed as completely bare on Christmas Morning was 1957; prior to that it was 1943. (*Note there are some missing data with the Fargo and UND/NWS snowfall and snow depth data set; yet the dataset is sufficiently complete to make this an accurate assessment.)
What are the chances for a White Christmas this year? The latest climate outlooks, which take up into the middle of December suggest an enhanced risk for above normal precipitation with below median temperatures. So the odds of a White Christmas in 2012 are looking a bit better - but there are no sure bets in weather.