The Role of Synoptic‐Scale Weather Systems on the Ohio River Valley, <scp>USA</scp> , Snowfall Variations and Trends

ABSTRACT Over the last 75 years, the Ohio River Valley has experienced significant changes in snowfall frequency, timing and magnitude that resulted in meaningful societal impacts. Through the application of a synoptic climatology, this study furthers the understanding of the synoptic‐scale atmospheric forcings responsible for snowfall and explains how their variations influenced observed snowfall trends from 1948 to 2021. Three dominant atmospheric environments were identified as being responsible for snowfall in this region: (1) types resulting in northwesterly flow conductive to lake‐effect snowfall primarily affecting the northeast region, (2) types with mid‐latitude cyclones generating wrap‐around or frontal snowfall in the central and southern regions and (3) types with high‐pressure centers over or adjacent to the region producing lighter snowfall due likely to smaller‐scale processes. Analysis revealed significant temporal trends in the seasonal frequencies of specific snowfall types that, in combination with changes to daily snowfall magnitudes over time, result in significant trends to seasonal snowfall totals per type and align with previously reported domain‐wide snowfall trends. Further, many of the snowfall‐producing weather types' inter‐annual frequencies were significantly correlated to the phase of teleconnection indices. When the Arctic Oscillation (AO) and North Atlantic Oscillation (NAO) were negatively phased, more than half of the weather types were significantly more frequent due to the larger‐scale atmosphere providing suitable conditions for the development of the snowfall‐producing types. These findings underscore the importance of understanding the integration of weather systems across scales and how changes manifest across a cascade of physical forcing mechanisms.