Temporal trends and large-scale atmospheric and oceanic forcings of central U.S. snowfall producing weather systems, 1948–2021

Abstract Snowfall across the central U.S. has undergone significant changes over the last 50–100 years, both with respect to inter-annual totals and event frequencies. While changes are often attributed to warming atmospheric conditions, to-date, there have been limited investigations quantitatively evaluating the potential for changes in snowfall producing weather systems being partially responsible for the observed snowfall trends. Here we conduct a synoptic classification to evaluate how snowfall producing weather systems’ snowfall totals, snowfall intensities, inter-annual and intra-annual frequencies, and inherent meteorological characteristics have varied and changed in the central U.S. from 1948 to 2021. Of the 10 analyzed weather types, the majority exhibit linear trends in snowfall in various sub-regions of the domain ranging from 110 mm increases in seasonal snowfall to 180 mm reductions over the 73-year period. For five of the weather types, changes in snowfall are partially attributed to changes in the frequency of events, with three types becoming less frequent and two types becoming more frequent over time. Additionally, nearly all of the types exhibited significant changes in their inherent meteorological characteristics over time, such as dew point temperatures, sea-level pressures and temperatures, that suggest some of the types became more or less favorable for generating snowfall in specific sub-regions. Trends in both the types’ frequencies and meteorological characteristics likely play a meaningful role in influencing the observed snowfall trends. Further, the interannual frequency of the types and their snowfall are significantly related to a number of large-scale teleconnection indices known to influence the hydroclimatology of North America.