NOAA Atlas 15: Updated Extreme Precipitation-Frequency Estimation Methodology in a Non-Stationary Climate

Recent studies have shown that the magnitudes and frequencies of extreme precipitation amounts may change over time and that future climate conditions may not be represented by the past observed precipitation. NOAA is currently developing a new statistical framework, known as NOAA Atlas 15, to update NOAA Atlas 14 precipitation-frequency estimates to account for non-stationarity in historical observations (Volume 1), as well as future climate conditions (Volume 2). Results will be developed as seamless high-resolution grids of precipitation-frequency estimates for exceedance probabilities through 1 in 1,000 for durations from 5-minutes through 60-days for the whole country. Critical to this work is the vigorous quality control and use of all appropriate precipitation data which increases the robustness of the analysis and improves the spatial reliability of the resulting grids. That said, associated research will evaluate best approaches for key challenges in the process, from selection of time series used in the analysis, distribution parameterization under non-stationary conditions, selection of appropriate spatial and temporal covariates for the parameterization and accounting for changes in density of stations through time. This talk will illustrate the overall approach and some of the scientific challenges to be addressed by the associated research. The research will help ensure that NOAA Atlas 15 provides valuable information used in the design and construction of civil engineering water resources infrastructure in a changing climate.