Intra-annual snowfall variability in the central United States

Snowfall in the central United States has been shown to be highly variable at interannual timescales and subjected to long-term linear trends. However, limited understanding is available about the intra-annual variations and trends in snowfall within this region. Using a selection of GHCN daily snowfall observations and statistical analyses, this study develops a monthly climatology of snowfall characteristics in the central United States from 1948 to 2021. Here we find larger magnitude snowfall events have a greater relative frequency to seasonal snowfall late in the snow season, have increased in frequency in the western and northern regions of the basin, and contribute to a bimodal distribution of monthly snowfall in these sub-regions. While snowfall has significantly increased over time within the northern and western regions of the domain by as much as 83%, snowfall has significantly decreased by much as 46% in the southern and eastern regions. Further, March snowfall totals and event frequencies have declined across the vast majority of the study domain, with maximum decreases in eastern IA of approximately 50%. When coupled with increases in snowfall and snowfall events in February, this suggests a shift in the snowfall season with time in this portion of the study region. Such results may be of particular interest to snow and water resource managers where integration of the nonstationarity of snowfall events and totals with time into management plans may yield better solutions.