CHARLESTON, WV (LOOTPRESS) – The National Weather Service is seeking public feedback on proposed changes to the Weather Prediction Center’s Excessive Rainfall Outlook, including the addition of a new risk category for flash flooding.
The proposed update would expand the current Excessive Rainfall Outlook, or ERO, from four risk levels to five. A new “Enhanced” risk category would be added between the existing Slight and Moderate risk levels.
Under the proposal, the five categories would be:
- Level 1 – Marginal: 5%
- Level 2 – Slight: 15%
- Level 3 – Enhanced: 25%
- Level 4 – Moderate: 40%
- Level 5 – High: 70%
The Weather Prediction Center said the new Enhanced category would allow forecasters to communicate an elevated threat for localized or regional flash flooding without immediately moving an area into the higher-impact Moderate Risk category.
The numerical Level 1 through Level 5 system would also more closely resemble the Storm Prediction Center’s five-level Convective Outlook scale used for severe thunderstorms and tornado threats.
Officials say the change is designed to make National Weather Service hazard graphics more consistent and easier for emergency managers, broadcasters and the public to understand when multiple weather threats are occurring.
The Excessive Rainfall Outlook forecasts the probability that rainfall will exceed local Flash Flood Guidance within 25 miles of a location across the contiguous United States. Outlooks are issued for Days 1 through 5.
Forecasters develop the outlook by analyzing rainfall thresholds from 12 River Forecast Centers along with atmospheric moisture, wind patterns and numerical weather prediction models. The product is intended to identify areas where rainfall could become heavy enough to cause flash flooding or push rivers and streams toward bankfull conditions.
If approved, the new five-level system would eventually appear on National Weather Service and Weather Prediction Center websites displaying Excessive Rainfall Outlook graphics.
The NWS said no changes will be made to operational AWIPS data feeds, GIS systems or product dissemination while the proposal is under review.
The public can compare the existing Excessive Rainfall Outlook with the proposed version through the Weather Prediction Center’s website.
Comments on the proposal are being accepted through September 5, 2026.
Feedback can be submitted through the NWS survey at:
https://www.surveymonkey.com/r/ProposedChangestoERO
Additional information and examples of the proposed changes are available through the Weather Prediction Center.
