Precipitation Isopluvials 100 year storm inches in 24hr

Regional Frequency Analysis (RFA) in combination with L-moments is a methodology that greatly reduces sampling variability and can provide robust PF estimates. RFA is conducted where a given phenomenon (precipitation) is measured at multiple sites and the data from the multiple sites can be grouped for statistical analysis to reduce sampling variability and improve frequency estimates. L-moments are particularly well-suited to statistical analysis of environmental data that commonly have high skewness. RFA was used to develop gridded datasets of 24-hour precipitation magnitude-frequency for a range of recurrence intervals of interest for stormwater and water quality treatment design applications. Datasets used in the analysis span 1940-2024.