October 2024
National Academies Consensus Report: Modernizing Probable Maximum Precipitation
Modernizing estimation of maximum possible precipitation for assessing dangers to critical infrastructure.
Image courtesy of National Academies of Sciences, Engineering and Medicine
This flowchart illustrates the proposed strategy and timeline for updating PMP that the committee recommends to NOAA and the broader community.
The Science
Probable maximum precipitation (PMP) is the maximum possible amount of rain that might fall in a storm in a location of interest. Since the early 1900s, it has been estimated using rainfall measurements collected from storms across the United States. It has been used to help assess the danger that a dam or nuclear power plant might experience damage. The way that PMP has been estimated is quite old and does not allow scientists to estimate uncertainty or account for the effects of climate change.
The Impact
NOAA asked a National Academies committee to recommend how to update the current approach to estimating maximum rainfall. The committee recommended that NOAA, with the scientific community, run many simulations with climate models that can simulate very extreme storms. The simulations can be analyzed using statistical methods to estimate extreme rainfall amounts with uncertainty. By running simulations with increased amounts of greenhouse gases in the atmosphere, the simulations can estimate the effect of climate change on extreme rainfall.
Summary
The proposed strategy provides NOAA with a path to modernizing estimation of extreme rainfall that can be used for assessing dangers to critical infrastructure into the future.
The high-resolution simulations could be useful for a wide variety of climate extremes at a variety of spatial and temporal scales.
Contact
Christopher Paciorek
Department of Statistics, UC Berkeley
Funding
Dr. Paciorek’s participation in the committee was funded through the Office of Science, US Department of Energy.
Publication
National Academies of Sciences, Engineering, and Medicine. “Modernizing Probable Maximum Precipitation”. The National Academies Press. (2024) [10.17226/27460].
Report release webinar, June 18, 2024.