Updated Present-Day Estimates of Heavy Rainfall Values in NOAA Atlas 15

Historical extreme precipitation estimates are used to design and manage today’s national infrastructure projects. The Office of Water Prediction (OWP) of the National Oceanic and Atmospheric Administration’s (NOAA) National Weather Service (NWS) is responsible for the development, production, and publication of such estimates for the United States and affiliated territories. These must be periodically updated to account for new data and improved methodologies. Under the recent Bipartisan Infrastructure Law, NOAA received federal funding to revise and update precipitation estimates nationwide, and now also to account for nonstationarity in the climate system. Currently in development, NOAA Atlas 15 (NA15) will be a source of authoritative rainfall information which will inform the design of infrastructure that is more resilient to climate-driven threats. Building upon the work of NOAA Atlas 14 which has been updating estimates for various parts of the country since the early 2000s, NA15 will include seamless estimates for all CONUS and oCONUS regions. Once complete, high-resolution gridded estimates for the nation will be published in two volumes: Volume 1 will provide present-day estimates accounting for temporal trends in historical rain gauge observations, and Volume 2 will provide estimates into the future under different carbon emissions scenarios informed by climate model projections. This presentation will describe ongoing efforts related to the development of NA15-Volume 1 which includes the creation of a new data repository and the evolution of a framework used to generate present-day precipitation frequency estimates. This work begins with a prototype framework over the state of Montana for which estimates are now accessible as gridded datasets and interactive graphics on a new web interface.