Hourly Precipitation Intensities at 4‐km Resolution Show Statistically Significant Increasing Trends From 1991 to 2022 in the CONUS‐404 Hydroclimate Reanalysis

Abstract Trends in hourly and daily precipitation statistics are studied using the CONUS‐404 hydroclimate reanalysis at 4‐km spatial resolution over the 1991–2022 period. Only a small fraction of CONUS shows statistically significant trends in the annual precipitation volume, number of wet days and mean wet‐day intensity. Significant increasing trends are however found in the mean wet‐hour precipitation intensity, with the trends being particularly pronounced in the Midwest. Fourier spectral analysis also attests for changes in the multiscale spatial and temporal organization of precipitation, and reveals that small‐scale short‐lived precipitation features have intensified at a higher rate than large‐scale long‐lived features. These results show that, even when no robust trend can be established from low‐resolution data, clear trends may emerge at a higher resolution, demonstrating the need for high‐resolution precipitation records for climate trend analysis.