Project Updates: Probable Maximum Precipitation Estimation Modernization
December 2025 Project Update
From project lead Kelly Mahoney:
As the end of 2025 approaches, we wanted to take an opportunity to thank each of you for your partnership and presence this year, reflect on the accomplishments of our team thus far, and look ahead at the plan for 2026.
Partnership Engagement Planning
Since June, our team has worked to prepare an initial draft of the Partnership Engagement Plan, which will allow us to continue brainstorming and collecting feedback on the best strategies for collaboration and engagement in the future. We have already received valuable feedback from the Association of State Dam Safety Officials (ASDSO) Extreme Precipitation Investigation Committee (EPIC) as well as some stakeholders within the nuclear community, which we have incorporated into this latest draft (PDF, 1.7 MB)
We also are planning for a (virtual) PMP Community-wide Update Meeting in February 2026; we will send out a save-the-date for this once we have it confirmed. One of the goals of this meeting will be to solicit and collect feedback on the draft of the Partnership Engagement Plan.
Accomplishments: June-December 2025
Here are select accomplishments since our last update, with more to be highlighted in the planned February Community Meeting.
- New Historical Storms webpage created: The first cases are now available on our new Historical Extreme Precipitation Events webpage. This resource hosts analyses of extreme precipitation events that currently determine PMP and may be of interest for updating future PMP. This also addresses several of the short-term recommendations from the National Academies' PMP Report. Additional cases will continue to be added, and recommendations from the community are welcome regarding additions or changes to the page.
- Virtual Workshop held: The NOAA Modernizing PMP project sponsored the National Academies of Science, Engineering, and Medicine’s "Extreme Rainfall in Mountainous Terrain: Modeling and observational challenges for warm-season precipitation” workshop held on November 4, 2025. This virtual workshop explored the scientific challenges and opportunities associated with observing, understanding, and modeling extreme warm-season rainfall in mountainous regions. Participants from across academia, government, and operational agencies provided incredibly valuable insights, and a recording of the workshop is available.
- Research progress: Our NOAA PMP team has been prolific in research progress this year; many of these accomplishments are evident in publications, presentations, and growing community connections. A snapshot of some of the exciting advancements can be found among a list of upcoming conference presentations.
Operational updates
We appreciate your ongoing support and patience as we navigate many changes across NOAA and our partner organizations who share our collective goal of modernizing PMP for the nation.
As a reminder, the modernization of PMP was codified in the Bipartisan Infrastructure Law / Infrastructure Investment and Jobs Act (BIL/IIJA) and the Providing Research and Estimates of Changes in Precipitation (PRECIP) Act. Funding was provided through the BIL/IIJA to begin the process of modernization; that funding was anticipated through September 2026; it remains unclear at this time what appropriations may be available to fill the gap when BIL/IIJA funding ends. See PMP Draft Timeline
Communication, Partnering, and Community
As before, we will continue to communicate through this email list and updates to the NOAA PMP project page, and we will send out a February Workshop Save-the-Date once we have it confirmed.
If you know of others that would like to sign up for updates from the NOAA PMP Team, the signup form at the bottom of the NOAA PMP project page. Any questions or feedback on the project can be emailed to psl.pmp@noaa.gov.
Thank you again for your partnership in creating a community dedicated to modernizing PMP!
June 2025 Project Update
From project lead Kelly Mahoney:
The NOAA PMP team has been working hard to bring the vision of a modernized PMP to reality, and we are incredibly grateful for your support and interest in this work. We’re excited to share some of our accomplishments since December 2024, along with a roadmap for the next 3-6 months.
Accomplishments: January-June 2025
- Extreme Precipitation Event Case Study webpages are being developed which will host analyses of many events that determine PMP currently and may be of interest for updating future PMP. These webpages address several of the short-term recommendations from the NASEM Report, and we expect these webpages to go live by September 2025.
- Several papers have been submitted, accepted, and published documenting the representation of extreme precipitation in key NOAA datasets (e.g., James et al. 2025).
- Development and evaluation work remains ongoing for new experimental high-resolution, rapidly updating NOAA models that will also be leveraged for producing extended reforecast datasets to serve both modernizing PMP and the broader extreme precipitation-interested community.
- NOAA approved the use of IIJA PMP funding to support a National Academies of Science, Engineering, and Medicine workshop on orographic extreme precipitation.
- Partnership with US Army Corps of Engineers (USACE) to inventory, preserve, and make accessible historical data, analyses, maps, and records of extreme storm rainfall events used to estimate PMP.
- Partnership with the National Centers of Environmental Information (NCEI) to support user engagement strategy and implementation through summer 2026.
Roadmap: July - December 2025
- Develop a partnership engagement strategy and identify opportunities for co-engagement with other extreme precipitation products (e.g., NOAA Atlas 15).
- Begin implementing partner engagement to inform the early stages of PMP definition and development.
- Begin developing an implementation plan that will guide NOAA’s approach to implementing the recommendations in the NASEM Report.
Operational updates
We appreciate your ongoing support and patience as we navigate many changes across NOAA and our partner organizations who share our collective goal of modernizing PMP for the nation.
As you may know, federal agencies are undergoing a comprehensive review of activities, projects, and personnel to ensure all initiatives align with the current administration’s priorities. This process has resulted in some unexpected changes to the NOAA PMP team to which we are adjusting.
In addition, the modernization of PMP was codified in the Bipartisan Infrastructure Law / Infrastructure Investment and Jobs Act (BIL/IIJA) and the Providing Research and Estimates of Changes in Precipitation (PRECIP) Act. Funding was provided through the BIL/IIJA to begin the process of modernization; that funding is anticipated through September 2026. However, the timeline for developing PMP lasts through 2030, and it is unclear at this time what appropriations may be available to fill the gap when BIL/IIJA funding ends.
Communication, Partnering, and Community
Despite the challenges, the NOAA PMP team remains dedicated to this important work, and will keep you updated with our progress.
- Communication will continue through this email list and updates to the NOAA PMP project page.
- You will hear from us again no later than December 2025 with another update.
- If you know of others that would like to sign up for updates from the NOAA PMP Team, please have them visit the signup form at the bottom of the NOAA PMP project page.
- For questions or feedback on the project, please do not hesitate to reach out via email to psl.pmp@noaa.gov.
Thank you again for your partnership in creating a community dedicated to modernizing PMP!
Read the original email updatePMP presentations
The following are PMP-supported presentations at the American Geophysical Union's Annual Meeting in December 2025:
- A large ensemble of kilometer-scale downscaled climate simulations for modernizing extreme precipitation guidance for the nation
- From Scientific Experts to Applied Users and Everyone in Between: Implementing an Engagement Strategy for Modernizing NOAA’s Probable Maximum Precipitation Estimates that Serves All Users
The following are PMP-supported presentations at the American Meteorological Society’s Annual Meeting in January 2026:
- Ability of in-development convection-allowing forecast systems to simulate precipitation extremes for the non-Contiguous United States
- Analysis of High-Resolution, Long Period-of Record QPE Using Quality Controlled Hourly Gauge Data
- Assessing Fitness-for-Purpose in Extreme Precipitation Datasets: Challenges, Approaches, and Emerging Best Practices
- Classifying Short-Duration Extreme Precipitation Events in NYC
- Evaluating Land Surface Modeling and Data Assimilation Approaches for Advancing RRFS Development
- Evaluation of the Spatial Representation of Precipitation in Gridded Datasets
- Examination of HRRR Forecast Performance During Extreme Precipitation Events
- From Scientists to End-Users and Everyone in Between: Implementing an Engagement Strategy for Modernizing NOAA’s Probable Maximum Precipitation Estimates that Serves All Users
- From Scientists to End-Users and Everyone in Between: Implementing an Engagement Strategy for Modernizing NOAA’s Probable Maximum Precipitation Estimates that Serves All Users
- How Much Can the Models Rain? A Preliminary Convection-Allowing Model Climatology of Extreme Precipitation
- Investigating U.S. Extreme Precipitation Regimes Using Self-Organizing Maps
- Representation of Extreme Rainfall in NOAA’s Experimental MPAS Forecasts during the 2025 Warm Season
- The Development of an EnKF for Assimilating Cloud Ceilometer Observations in a Regional NWP System