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Public Information Statement 23-55 Updated
National Weather Service Headquarters Silver Spring MD
353 PM EDT Wed Sep 3 2025

To: Subscribers:
 -NOAA Weather Wire Service
 -Emergency Managers Weather Information Network
 -NOAAPort
 Other NWS Partners, Users and Employees

From: David R. Vallee
 Director, Service Innovation and Partnership Division
 Office of Water Prediction, National Water Center

Subject: Updated: Soliciting Comments on Experimental Flood
Inundation Mapping (FIM) Services through September 30, 2026

Updated to extend the comment period and to expand the areas for
which these services are available.

Through September 30, 2026, the NWS is seeking user feedback on
experimental Flood Inundation Mapping (FIM) visualizations and
services. These new services were introduced in September 2023
for portions of the United States comprising roughly ten percent
of the United States population.  This update incorporates a
significant expansion to include over sixty percent of the
United States population.

FIM visualizations and services will be available on September
3, 2025 for areas covered by the County Warning Areas (CWA) of
the following National Weather Service (NWS) Weather Forecast
Offices (WFOs):

New availability for these WFO CWAs:
Anchorage, AK
Eureka, CA
Hanford, CA
Los Angeles, CA
Sacramento, CA
San Diego, CA
San Francisco, CA
Atlanta, GA
Tallahassee, FL
Honolulu, HI
Des Moines, IA
Quad Cities, IA/IL
Dodge City, KS
Goodland, KS
Topeka, KS
Wichita, KS
Minneapolis, MN
Raleigh, NC
Hastings, NE
Omaha, NE
Albuquerque, NM
El Paso, NM
Reno, NV
Cleveland, OH
Norman, OK
Medford, OR
Columbia, SC
Greer, SC
Sioux Falls, SD
Amarillo, TX
Brownsville, TX
Lubbock, TX
Midland, TX
San Angelo, TX
Wakefield, VA
Burlington, VT
La Crosse, WI

Continued availability for these WFO CWAs:

Birmingham, AL
Huntsville, AL
Mobile, AL
Little Rock, AR
Tallahassee, FL
Lincoln, IL
Indianapolis, IN
Jackson, KY
Louisville, KY
Paducah, KY
Lake Charles, LA
New Orleans/Baton Rouge, LA
Shreveport, LA
Baltimore/Washington DC, MD
Kansas City, MO
Springfield, MO
St. Louis, MO
Jackson, MS
Buffalo, NY
Binghamton, NY
Albany, NY
Wilmington, OH
Tulsa, OK
Pendleton, OR
Portland, OR
Philadelphia, PA
Pittsburgh, PA
State College, PA
San Juan, PR
Memphis, TN
Morristown, TN
Nashville, TN
Austin/San Antonio, TX
Corpus Christi, TX
Fort Worth/Dallas, TX
Houston/Galveston, TX
Blacksburg, VA
Seattle, WA
Spokane, WA
Charleston, WV

The experimental FIM provided by the NWS depicts the spatial
extent of inundation areas at a 10-meter horizontal resolution
for flood events.  For this experimental period, inundation
depth will not be provided.

The FIM services include a near-real-time analysis of the latest
inundation extent as well as forecasts of maximum inundation
over the subsequent 5-day period. For Hawaii, Puerto Rico and
the U.S. Virgin Islands, forecasts for maximum inundation are
over the subsequent 48-hour period. The National Water Model
(NWM) will provide the discharge information from which the
inundation extent will be derived for the analysis FIM and for
one of the forecast FIM products. The NWS River Forecast Center
(RFC) forecasts will provide the discharge information for the
other forecast FIM product. Inundation extent is determined for
each river or stream reach defined in the NWM river network,
which is derived from the National Hydrography Dataset Plus
(NHDPlus)for river and stream topology. In summary, the
following experimental products will be available:

Inundation extent mapping for the contiguous United States and
portions of South Central Alaska, including the Cook Inlet,
Kenai Peninsula, Copper River and Prince William Sound
Watersheds, as derived for the:

  1) Latest Analysis from the NWM Analysis and Assimilation
    (AnA) run, executed every hour.
  2) 5-Day Maximum from the NWM Medium Range Forecast (MRF)
     run, executed every 6 hours.  The maximum value for each
     river reach through the next 5-day period is used to
     determine inundation extent.
  3) 5-Day Maximum from the RFC Forecast. FIM is updated within
     an hour of any RFC issued forecast. The maximum value for
     each river reach for a time period up to the next 5 days
     is used to determine inundation extent.

Inundation extent mapping for Hawaii, Puerto Rico and the U.S.
Virgin Islands as derived for the:

  1) Latest Analysis from the NWM Analysis and Assimilation
    (AnA) run, executed every hour.
  2) 48-Hour Maximum from the NWM Short Range Forecast (SRF)
     run, executed every 12 hours (00Z and 12Z for Hawaii and
     06Z and 18Z for Puerto Rico and the U.S. Virgin Islands).
     The maximum value for each river reach through the next
     48-hour period is used to determine inundation extent.

In addition to the real-time (dynamic) products above, static
Categorical  FIM (CatFIM) maps will be available for select NWS
River Forecast Points within the FIM domain. CatFIM is a method
developed by the National Water Center (NWC) to create a static
inundation extent mapping library for the official NWS flood
stage category thresholds [Action, Minor, Moderate, Major, and
Record].

These FIM services are available for viewing within the National
Water Prediction Service (NWPS) website and the web-based NWS
Geographic Information System (GIS) National Viewer (dynamic FIM
products), a national geospatial viewer that provides access to
the experimental FIM services.

NWPS is the NWS hydrologic web page for access to river
forecasts, output from the National Water Model and other water
related products. It is accessible here:

https://water.noaa.gov

The NWS GIS Viewer presents visualizations of many operational
products supporting the NWS water resources program and other
NWS service programs.  The GIS Viewer water resources
information, including FIM, is accessible here:

https://viewer.weather.noaa.gov/water

The dynamic FIM services are also available as REST
(Representational State Transfer) services through the NWS
Office of Water Prediction s cloud based dissemination system
known as HydroVIS. This system allows user clients to access a
REST service via an Application Programming Interface (API) for
the desired inundation service and to subsequently use and
display the FIM in their own GIS system.

https://maps.water.noaa.gov/server/rest/services

This deployment of FIM services is the third year of a planned
four year phased approach to deploying FIM services across the
United States and Territories.A description of the concept of
FIM services, product examples, and requirements explanation can
be found in the Services Description Document (SDD) at the
following link:

https://nsdesk.servicenowservices.com/api/g_noa/nwspc/res2/d05b7
68747672a50f6550c03e16d4399

Feedback on the experimental FIM services is being sought from
the users of this information. Comments can be provided by users
outside of those areas with the new services.

https://www.surveymonkey.com/r/ExpFIMServices_2025

There will be additional opportunities for comment and review as
experimental FIM services are expanded to other parts of the
United States.

Any questions, comments, or requests regarding this
implementation should be directed to the contact below.

David R. Vallee
Director, Service Innovation and Partnership Division
Office of Water Prediction, National Water Center
Tuscaloosa, AL
nws.fim@noaa.gov

National Public Information Statements are online at:

https://www.weather.gov/notification/