NOUS41 KWBC 121355

PNSWSH



Public Information Statement PNS25-78

National Weather Service Headquarters Silver Spring MD

855 AM EST Fri Dec 12 2025



To:	 Subscribers:

	 -NOAA Weather Wire Service

	 -Emergency Managers Weather Information Network

	 -NOAAPort

	 Other NWS Partners and NWS Employees



From:	 Saeed Moghimi

	 Acting Chief, Coastal Marine Modeling Branch

	 NOS/Office of Coast Survey/Coast Survey Development

	 Laboratory



Subject: Soliciting Comments on the Upgrade of the Surge and

Tide Operational Forecast System (STOFS) to Version 3.1.0

through January 16, 2026



The Coast Survey Development Laboratory (CSDL) in

NOAA/NOS/Office of Coast Survey is proposing to upgrade the

Surge and Tide Operational Forecast System (STOFS) to Version

3.1.0 in April 2026. CSDL is seeking comments on this proposed

upgrade through January 16, 2026. If approved, a Service Change

Notice (SCN) will be issued at least 30 days before

implementation of STOFS V3.1.0 with more detailed information.



STOFS V3.1.0 represents an upgrade of the STOFS modeling system,

last upgraded in May 2024. STOFS V3.1.0 contains several

enhancements improving model performance, resolution, and

coverage, including upgrades to both the global (STOFS-2D-

Global) and Atlantic (STOFS-3D-Atlantic) components, and the

addition of a new component for the Pacific (STOFS-3D-Pacific).

Model upgrades include:



    -Upgrades to STOFS-2D-Global, which uses the ADvanced

CIRCulation (ADCIRC) model core:

	  -Inclusion of a gridded bias correction. This bias

correction uses the current station bias correction approach

used in operational STOFS-2D-Global (v2.1), which corrects the

station water level forecast guidance biases by removing the

bias between the observed water levels at NOS/CO-OPS stations

and most recent 5 days of nowcast water levels. This bias

correction at stations is then propagated across the entire

global grid using a graph diffusion approach. The result is both

station and gridded output is bias corrected.



	  -Addition of a few stations to the output, as

requested by National Weather Service forecast offices. Also,

some redundant stations are removed from the output.



    -Upgrades to STOFS-3D-Atlantic, which uses the Semi-

implicit Cross-scale Hydroscience Integrated System Model

(SCHISM) model core:



	  -Major improvements to the mesh in watersheds (rivers,

levees) and coastal areas (barrier islands, jetties/breakwaters,

Intracoastal Waterway); and local mesh refinements requested by

the community. These refinements resulted in improvements to the

water level forecast guidance.



	  -Inclusion of a dynamic adjustment (bias correction)

of open boundary conditions, to account for missing physics in

the model, including steric effects, to improve the model’s

overall accuracy. This bias correction is calculated by

averaging the model’s nowcast bias for the past two days over 11

U.S. East Coast open coast NOS/CO-OPS stations. This bias is

then uniformly applied to the open boundary conditions to force

the model simulations.



	  -Station output will now be referenced to local mean

sea level (LMSL), while gridded output will remain referenced to

xGEOID20b.



    -Addition of the STOFS-3D-Pacific component, which will use

the SCHISM model core, to provide 3D baroclinic and surface

current coverage for the north Pacific basin, from 30 degrees

South to the Bering Strait. STOFS-3D-Pacific will use input from

the National Water Model and Copernicus’ Global Flood Awareness

System (GloFAS) global hydrology to include inland hydrology and

extreme precipitation effects on coastal flooding, and will also

provide surface currents for marine navigation use.





CSDL will evaluate all comments to determine whether to proceed

with all portions of this upgrade.



Send comments on this proposal for the upgrade of STOFS

to Version 3.1.0 by January 16, 2026 to:

  Gregory Seroka

  Gregory.Seroka@noaa.gov

  Saeed Moghimi

  Saeed.Moghimi@noaa.gov

  Edward Myers

  Edward.Myers@noaa.gov



A web page describing STOFS and providing real-time

verification statistics can be found at:

https://polar.ncep.noaa.gov/estofs/



STOFS model forecast guidance can also be viewed at:

nowcoast.noaa.gov



STOFS output can also be accessed via the AWS cloud

courtesy of NOAA Open Data Dissemination (NODD) at:

https://registry.opendata.aws/noaa-gestofs/

https://registry.opendata.aws/noaa-nos-stofs3d/



National Public Information Statements are online at:

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