Is this the year for a White Christmas? It might depend on how do you define a White Christmas. Does it count if there is snow on the ground, even if it fell before Christmas Day? Does it count when snow fell on December 25th, even if it is not recorded until the 26th? It is a White Christmas, for most of us, if there is snow on the ground or if snow falls on the 25th. In northeast Kansas, this occurs only one in every five years (Figure 1).
Figure 1. Historical probability of a white Christmas (Climate Prediction Center)
Our last White Christmas in Manhattan was in 2017, when an inch remained on the ground from an earlier storm. The last time snowfall was reported on the 25th was in 2009, when 6.1 inches was reported.
On the other hand, a snowy start to the new year is more likely. Historical records indicate the odds are one in four years to have snow at the new year. The most recent Climate Prediction Center’s 6-10 Day Outlook indicates a strong probability of wetter-than-normal conditions to end the year (Figure 2).
Figure 2. 6-10 Day Precipitation Outlook (NOAA)
The major question is what track the frontal systems will take, and how that influences the form of precipitation. A more southerly track will bring colder air into play, reducing the amount of moisture and increasing the chances that it will be in the form of snow. A more northerly track will increase the amount of moisture available, but also make it more likely that the precipitation will fall as rain.
Mary Knapp, Assistant Climatologist
Christopher “Chip” Redmond, Kansas Mesonet Manager