A White Christmas for Michiana?
The snow machine has been pretty active over the last several days across Michiana. Some have seen more than 10" of snow in just under a week. Everyone has seen at least some snowfall this season. Now, you may be wondering when it'll stop snowing. Well, it appears as though the pattern will change around December 16-17 as milder air enters the forecast, thus hindering our chances of seeing snow. That "mild" pattern -- highs in the 30s and perhaps low 40s -- will only last through roughly December 23rd or so. Beyond that, our meteorologists are looking at data that suggests an abrupt return to colder weather for Christmas and perhaps even New Year's.
First things first; let's discuss how often Michiana sees a "White Christmas." By definition, a "White Christmas" is when there is at least 1" of snow on the ground at any point on Christmas Day. Or, there could be snow falling on Christmas Day itself. If it snows 6" on Christmas Eve and at least 1" of that snow is on the ground on Christmas Day, it counts as a White Christmas. Historically speaking, Michiana as a whole sees a White Christmas about 41-60% of the time. South Bend itself sees a White Christmas roughly 50% of the time. If you live in Michigan, your chances of a White Christmas range from 51-60%. You get the picture. If you live north, your chances are higher. If you live south of U.S. 30, your chances are closer to 40% or so.
If you do the math, that means during every 10-year stretch, South Bend sees five White Christmases, on average. Of course, this is just a historical average. During any given 10-year stretch, it's possible to see more or less White Christmases. For example, we could go 10 years without a White Christmas. On the other side, it's possible to have a White Christmas for 10 or more years in a row. During the 1950-1960 stretch, there were seven White Christmases. South Bend has had as little as 0" of snow on the ground on Christmas, and as much as 16" has fallen on the big holiday! That total occurred back in 1951. The last time South Bend recorded 1" of snowfall on Christmas Day was 2013, when exactly 1" of snow fell. Other than that, it has been very snow-less locally. In the last 14 years, 2013 is the only year in which at least 1" of snow fell on Christmas Day. It's important to remember that there could have been 1" of snow on the ground on any given Christmas even if nothing fell on Christmas Day itself.
Now that's out of the way so we can begin looking ahead to this year. Christmas is only 11 days away as this article is being written. That means some of our forecast models are now spitting out data for the big day. As mentioned above, a cold pattern looks increasingly likely across the eastern half of the United States around Christmas and possibly lasting through the New Year. The other half of the equation is, "will there be snow along with the cold?" That question is a little more difficult to answer. However, now that we are closer to Christmas, we can begin to gather some broad thoughts and ideas pertaining to precipitation. First and foremost, there is certainly a chance that we will see snow fall 1-2 days before Christmas, or on the actual holiday. Models do hint at that possibility at this juncture.
One particularly successful long-range product that meteorologists use is displayed just above. It is the latest probability of there being a snow depth of at least 1" on Christmas. The red colors indicate a near-guaranteed chance. The gray and white shades indicate a near-zero shot. South Bend and all of Michiana fall right between those two extremes. Pulaski, Starke, Marshall, Fulton, and Kosciusko Counties fall in the 40-50% probability contour for seeing a White Christmas. La Porte, St. Joseph, Elkhart, and LaGrange Counties fall in the 50-60% probability contour. Meanwhile, Berrien, Cass and St. Joseph Counties in Michigan have roughly a 65% chance of seeing at least 1" of snow on the ground at any point on Christmas Day.
So, in short, the chances of a "White Christmas" are definitely there this year, per the latest data. Time to wait and see!