433
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/
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