Unmanned aircraft systems (UASs) provide unique observations not readily available from piloted aircraft or ground- and satellite-based remote sensors. For example, they can reach difficult to observe areas in the Arctic (Reuder et al. 2012; de Boer et al. 2016b, 2018), in tropical cyclones (Cione et al. 2020), and within the atmospheric boundary layer (Jacob et al. 2018), and provide more routine measurements over a longer time range with repetitive vertical and horizontal profiles than piloted aircraft can. Furthermore, there are many scientific applications of UASs that go beyond weather research, which can aid weather applications and, in some instances, draw from weather applications. Although recent efforts have accelerated the development of UAS platforms and instruments (e.g., Wildmann et al. 2014; de Boer 2016a; Barbieri et al. 2019; Bell et al. 2020), there is still considerable uncertainty in how to best acquire and use these observations for improving forecasts, how to integrate them with other observations currently being obtained, and to enable process studies to improve conceptual and numerical modeling of the atmosphere and its constituent gases, aerosols, pollutants, and hydrometeors. To initiate a community effort for addressing such issues and to build upon the efforts of other community groups, such as the International Society for Atmospheric Research using Remotely-Piloted Aircraft (ISARRA; http://isarra.org; de Boer et al. 2019), a workshop emphasizing the scientific applications of UASs was held at the National Weather Center (NWC) in Norman, Oklahoma, in October 2019 (all presentations are available at https://cimms.ou.edu/index.php/research/symposiums/symposium2019/). The workshop brought together diverse communities actively working on various aspects of UAS-based atmospheric science.