NOUS41 KWBC 051725 PNSWSH Public Information Statement 26-57 National Weather Service Headquarters Silver Spring MD 125 PM EDT Wed Aug 5 2026 To: Subscribers: -NOAA Weather Wire Service -Emergency Managers Weather Information Network -NOAAPort Other NWS Partners and Employees From: Kathryn Gilbert, Deputy Director Weather Prediction Center Subject: Soliciting Comments on the Proposed Changes to the Excessive Rainfall Outlook through September 5, 2026 The National Weather Service (NWS) is soliciting comments on proposed changes to the Weather Prediction Center (WPC) Excessive Rainfall Outlook (ERO) through September 5, 2026 WPC is proposing transitioning the ERO's risk tier scale from four levels to five, better aligning with similar national forecast risk graphical outputs. The new proposed risk categorizations will continue to integrate numeric tier indexing (Levels 1 through 5) for the daily outlooks, Days 1 through 5. The new risk category "Enhanced" uses a threshold of 25 percent and is situated between the existing "Slight" and "Moderate" risk categories. The ERO provides a graphical map forecasting the probability that rainfall will exceed Flash Flood Guidance within 25 miles of a point across the contiguous United States for Day 1 through Day 5. By synthesizing data from twelve River Forecast Centers, the WPC identifies specific 1, 3, and 6-hour rainfall thresholds likely to cause rivers and streams to reach bankfull capacity. To estimate these risks, forecasters analyze environmental factors like atmospheric moisture and wind patterns while utilizing advanced numerical models. The ERO helps translate traditional rainfall forecasts into environmental risk layers that allow emergency managers, broadcast media, and the public to easily identify regional corridors facing meaningful, high- impact flash flooding threats. This proposed framework update aims to close critical communication gaps and improve cross-product consistency across NWS hazard messaging. If approved, these changes would be reflected on all web interfaces displaying the ERO graphic suite. The ERO is available on the WPC website at the following URL: https://www.wpc.ncep.noaa.gov/qpf/excessive_rainfall_outlook_ero .php Examples of the current operational ERO and the proposed version of the ERO are provided at the link below for review and comment: https://www.wpc.ncep.noaa.gov/qpf/ero_proposed_changes.shtml Operationally, this allows forecasters to convey a heightened risk of localized or regional flash flooding without prematurely triggering high-impact messaging associated with a Moderate Risk. Additionally, numerical identifiers (Levels 1 through 5) will be appended to each category name as follows: Level 1 for Marginal (5%), Level 2 for Slight (15%), Level 3 for Enhanced (25%), Level 4 for Moderate (40%), and Level 5 for High (70%). This numeric alignment directly mirrors the Storm Prediction Center (SPC) Convective Outlook scale, reducing cognitive load for core partners managing multi-hazard severe weather and flash flood environments. changes will be made to operational AWIPS data feeds, GIS pipelines, or product dissemination during the comment period. More detailed information about the proposed changes to the ERO can be found in the NWS Product Description Document (PDD) at the following URL: https://nsdesk.servicenowservices.com/api/g_noa/nwspc/res2/a2169 21ecf560fd0fb6eb5f42f851c3b Please provide your feedback on the proposed changes detailed above through the following survey link by September 5, 2026: https://www.surveymonkey.com/r/ProposedChangestoERO If you have any additional questions, please contact: WPC Services Weather Prediction Center Riverdale Park, MD Email: wpcservices@noaa.gov National Public Information Statements are available at: https://www.weather.gov/notification/