Annual totals versus days with snow
Snowfall is most frequently reported as monthly, annual, or seasonal amounts. These are usually the totals for the given period, or the current normal. As might be expected, actual values can vary quite a bit from one part of the state to the next and from year to year. The most recent normal period (1981-2010) shows a strong gradient with the highest annual snowfall in the northwest and lesser amounts in the southeast (Figure 1).
Figure 1. Normal annual snowfall (WDL)
Snow on the ground
The annual or even monthly snowfall totals do not tell the whole story. The question you might ask is “how frequently do the snow events occur and also, how long does the snow persist?” Not surprisingly, that will vary from year to year and from location to location. Using 1981-2010 data and a 1-inch total as the threshold, in the northwest that average is as high as 40 days per year. In the south central and southeast, the averages are generally less than 10 days per year (Figure 2).
Figure 2. Average days with 1 inch or more of snow (WDL)
Another question that frequently comes to mind is whether the snow events are more or less frequent than earlier in our observed records. Here we compared three stations for changes in the snow events from 1900s to 2010s. Spatial differences across the state are shown in Figure 3, with the greatest frequency of snow covered days in Manhattan and Hays occurring in the 1970s. For Tribune, the highest average occurred in the 1980s. Manhattan, located in the eastern Kansas, showed an increased trend but decreased trends are depicted in both Hays and Tribune in western Kansas.
Figure 3. Days with snow cover in Tribune, Hays, and Manhattan by decade (Weather Data Library).
Mary Knapp, Assistant State Climatologist
Xiaomao Lin, State Climatologist