Examining Extreme Precipitation Seasonality in the Eastern USA

Global warming is likely to impact extreme storms in the eastern United States (eUS), ultimately affecting the empirical probability distribution of extreme daily precipitation timing. In this work, probabilistic properties of dates of annual maximum precipitation (AMP) were studied using circular statistics at 581 sites in the eUS (1950-2019). The circular measures of location, standard deviation, and dispersion were used in the long-term samples of dates of maxima. Furthermore, a kernel density method was used to assess distributional modes of timing of AMP. The statistical summaries showed that seasonality is pronounced across the eUS, and it is strong at the East North Central region. However, the non-parametric tests indicate a very few sites in the South and Southeast regions with uniform distribution while modality of significant AMP seasons strikes in most locations. To this end, the results of circular density unveil multi significant seasons of AMP within local and regional scales. The summer and fall are significant in Central, East North Central, Southeast, and Northeast, which is significant in spring as well. While winter and fall are significant seasons in many sites in the South region. Our results of extreme precipitation seasonality have a critical role in the flood risk management and preparedness.