####018014554#### NOUS41 KWBC 221820 AAF PNSWSH Service Change Notice 23-124 Updated National Weather Service Headquarters Silver Spring MD 220 PM EDT Mon Apr 22 2024 To: Subscribers: -NOAA Weather Wire Service -Emergency Managers Weather Information Network -NOAAPORT -Other NWS Partners and Employees From: Ben Kyger Director, NCEP Central Operations Subject: Updated: Upgrade of the Surge and Tide Operational Forecast System (STOFS), Effective May 14, 2024 Updated to reflect the new implementation date of May 14, 2024 and to update version number to v2.1.7. On or about Tuesday, May 14, 2024 beginning with the 1200 Coordinated Universal Time (UTC) cycle, the National Centers for Environmental Prediction (NCEP) will be upgrading the Surge and Tide Operational Forecast System (STOFS) to v2.1.7. STOFS v2.1.7 represents a major upgrade of the STOFS modeling system. It was last upgraded in January 2023. STOFS v2.1.7 contains several enhancements improving model performance, resolution, and coverage. It includes upgrades to the global modeling system (STOFS-2D-Global) and to the 3D component for the Atlantic basin (STOFS-3D-Atlantic). Model upgrades for STOFS-2D-Global (ADCIRC-based) include: - Inclusion of bias correction at station locations where NOS/CO-OPS observations are available. This bias correction a) computes the bias at these stations by subtracting the combined (storm surge + tide) water level forecast guidance from the observed water level, b) removes this hourly bias from the current cycle’s 6-hour nowcast, c) averages the bias over 5 days using the most recent 5 days of nowcasts and observations, and d) removes this average bias from the future forecast guidance (with a 12- hour linear interpolation from current bias to average bias). This post- processing bias correction is implemented in STOFS-2D-Global in the same way that Extra-Tropical Storm Surge (ETSS) implements it (also called “anomaly”, which is the same as the negative bias). Note that no gridded bias correction is implemented in this version of STOFS-2D-Global. - Improved temporal resolution for GFS forcing, by including hourly GFS forcing out to 5 days in the forecast, then 3-hourly from 5 days to 7.5 days in the forecast. Previously, 3-hourly GFS forcing was used for the entire forecast period. - Improvements to coastal topography, bathymetry, friction values, and the mesh, for improved accuracy of water level forecast guidance. Specifically, there are improvements to the bottom boundary conditions (friction, topography, and bathymetry), and a few mesh nodes were adjusted for improvement in performance. Also, a model output station was added at a relatively new tide gauge at NOS/CO-OPS Bremerton, WA (9445958). Model upgrades for STOFS-3D-Atlantic (SCHISM-based) include: - Major improvements to the mesh in the watersheds, including better resolving of river channels to enhance watershed flow and connectivity and to minimize ponding. The mesh in coastal areas such as the Great South Bay and Shinnecock Bay is also improved for enhanced accuracy of water level forecast guidance. - Incorporation of satellite altimetry observations, specifically absolute dynamic topography (ADT), to improve open ocean boundary conditions and overall accuracy. Also, xGEOID20b is used instead of NAVD88 to improve model initialization and vertical datum referencing. Station output will remain in NAVD88, while gridded output (e.g. *field*.nc and *.grib2) will be referenced to xGEOID20b. - Extending the forecast horizon from 48 to 96 hours into the future. - Expanding the model coverage east and north to include the St. Lawrence River and improve boundary conditions and overall accuracy, especially in the Gulf of Maine. New and existing data files for STOFS-2D-Global and STOFS-3D-Atlantic will remain at their current location on the NOAA Operational Model Archive and Distribution Service (NOMADS)/FTPPRD web services at: ftp://ftp.ncep.noaa.gov/pub/data/nccf/com/stofs/prod/ https://www.ftp.ncep.noaa.gov/data/nccf/com/stofs/prod https://nomads.ncep.noaa.gov/pub/data/nccf/com/stofs/prod/ Below are the changes to the files on NOMADS and FTPPRD web services: A. File additions and file name changes: - Additional forecast hours for STOFS-3D-Atlantic CONUS East and Puerto Rico (this data will also be made available via the existing NOMADS Grib Filter and OPeNDAP applications): stofs_3d_atl.tCCz.conus.east.f{hour}.grib2 stofs_3d_atl.tCCz.puertori.f{hour}.grib2 Where {hour} = {49,50,51,...,96}, and tCCz is forecast cycle: CC = 12 - The following STOFS-3D-Atlantic files experience file name changes, increased temporal resolution, and/or an extended forecast horizon that results in additional files: stofs_3d_atl.tCCz.f001_024.field2d.nc and stofs_3d_atl.tCCz.f025_048.field2d.nc become: stofs_3d_atl.tCCz.field2d_fhhh1_hhh2.nc Where {fhhh1_hhh2} = {f001_012,f013_024,f025_036,f037_048,f049_060,f061_072,f073_084,f085_ 096}, and tCCz is forecast cycle: CC = 12 stofs_3d_atl.tCCz.n001_024.field2d.nc becomes: stofs_3d_atl.tCCz.field2d_nhhh1_hhh2.nc Where {nhhh1_hhh2} = {n001_012,n013_024}, and tCCz is forecast cycle: CC = 12 stofs_3d_atl.tCCz.fields.out2d_forecast_day1.nc and stofs_3d_atl.tCCz.fields.out2d_forecast_day2.nc become: stofs_3d_atl.tCCz.fields.out2d_fhhh1_hhh2.nc Where {fhhh1_hhh2} = {f001_012,f013_024,f025_036,f037_048,f049_060,f061_072,f073_084,f085_ 096}, and tCCz is forecast cycle: CC = 12 stofs_3d_atl.tCCz.fields.out2d_nowcast.nc becomes: stofs_3d_atl.tCCz.fields.out2d_nhhh1_hhh2.nc Where {nhhh1_hhh2} = {n001_012,n013_024}, and tCCz is forecast cycle: CC = 12 B. Timeliness changes: - For the STOFS-2D-Global model, the GRIB2 and SHEF products will be delivered up to 20 minutes later. The NetCDF products will be delivered up to 30 minutes later, while the htp NetCDF files will be delivered up to 15 minutes earlier. - For the STOFS-3D-Atlantic model, the SHEF and NetCDF products will be delivered up to 45 minutes later, and the GRIB2 products will be delivered up to 70 minutes later. C. File size changes: - The expanded domain east and north and some SCHISM code I/O changes increase the following STOFS-3D-Atlantic file sizes: stofs_3d_atl.tCCz.fields.cwl.maxele.nc stofs_3d_atl.tCCz.conus.east.cwl.grib2 stofs_3d_atl.tCCz.puertori.cwl.grib2 Where tCCz is forecast cycle: CC = 12 - The reduction in the station number from 342 to 108 or 107 decreases the following file sizes: stofs_3d_atl.tCCz.fcast.station.profile.nc stofs_3d_atl.tCCz.ncast.station.profile.nc stofs_3d_atl.tCCz.points.cwl.temp.salt.vel.nc stofs_3d_atl.tCCz.points.cwl.nc stofs_3d_atl.tCCz.points.cwl.shef Where tCCz is forecast cycle: CC = 12 - The addition of stations increases the following file sizes: stofs_2d_glo.tCCz.points.cwl.shef stofs_2d_glo.tCCz.points.htp.shef stofs_2d_glo.tCCz.points.swl.shef Where tCCz is forecast cycle: CC = 00, 06, 12, and 18 - The increase in coverage to north of the Aleutian Islands increases the following file sizes: stofs_2d_glo.tCCz.alaska.cwl.grib2 stofs_2d_glo.tCCz.alaska.htp.grib2 stofs_2d_glo.tCCz.alaska.swl.grib2 stofs_2d_glo.tCCz.alaska.f{hour}.grib2 Where {hour} = {0,1,2,3,...,180}, and tCCz is forecast cycle: CC = 00, 06, 12, and 18 - The removal of coverage in the Gulf of California decreases the following file sizes: stofs_2d_glo.tCCz.conus.west.cwl.grib2 stofs_2d_glo.tCCz.conus.west.htp.grib2 stofs_2d_glo.tCCz.conus.west.swl.grib2 stofs_2d_glo.tCCz.conus.west.f{hour}.grib2 Where {hour} = {0,1,2,3,...,180}, and tCCz is forecast cycle: CC = 00, 06, 12, and 18 D. File content changes: - The Bremerton, WA and many other stations are added to the following STOFS-2D-Global files: stofs_2d_glo.tCCz.points.cwl.nc stofs_2d_glo.tCCz.points.htp.nc stofs_2d_glo.tCCz.points.swl.nc stofs_2d_glo.tCCz.points.cwl.shef stofs_2d_glo.tCCz.points.htp.shef stofs_2d_glo.tCCz.points.swl.shef Where tCCz is forecast cycle: CC = 00, 06, 12, and 18 - Dimension parameters (such as node, nele, nbou, nvel, and max_nvell) are changing in the following STOFS-2D-Global files due to the ADCIRC model grid change and the adjustment of a few mesh nodes: stofs_2d_glo.tCCz.fields.cwl.nc stofs_2d_glo.tCCz.fields.htp.nc stofs_2d_glo.tCCz.fields.swl.nc Where tCCz is forecast cycle: CC = 00, 06, 12, and 18 - A new processID "21", which is Extra-tropical Storm Surge Atlantic Domain (3D), is used for the following STOFS-3D-Atlantic GRIB2 files: stofs_3d_atl.tCCz.conus.east.f{hour}.grib2 stofs_3d_atl.tCCz.puertori.f{hour}.grib2 stofs_3d_atl.tCCz.conus.east.cwl.grib2 stofs_3d_atl.tCCz.puertori.cwl.grib2 Where {hour} = {1,2,3,...,96}, and tCCz is forecast cycle: CC = 12 - Due to the change of the vertical datum referencing to xGEOID20b for the STOFS-3D-Atlantic model, the number of stations is reduced from 342 to 108 or 107 (i.e. xGEOID20b to NAVD88 or MLLW conversion is not available for some stations). The affected files are: stofs_3d_atl.tCCz.fcast.station.profile.nc stofs_3d_atl.tCCz.ncast.station.profile.nc stofs_3d_atl.tCCz.points.cwl.temp.salt.vel.nc stofs_3d_atl.tCCz.points.cwl.nc stofs_3d_atl.tCCz.points.cwl.shef Where tCCz is forecast cycle: CC = 12 - The following files have new variables: Variable crs is added to provide the Coordinate Reference System (CRS) definition in the following file: stofs_3d_atl.tCCz.fields.cwl.maxele.nc Where tCCz is forecast cycle: CC = 12 Variables crs, SCHISM_hgrid_face_x, SCHISM_hgrid_face_y, SCHISM_hgrid_edge_x, SCHISM_hgrid_edge_y, evaporationRate, precipitationRate, windStressX, and windStressY are added in the following files: stofs_3d_atl.tCCz.fields.out2d_nhhh1_hhh2.nc stofs_3d_atl.tCCz.fields.out2d_fhhh1_hhh2.nc Where {nhhh1_hhh2}={n001_012,n013_024}, {fhhh1_hhh2}={f001_012,f013_024,f025_036,f037_048,f049_060,f061_072,f 073_0 84,f085_096}, and tCCz is forecast cycle: CC = 12 - A new type source "HMIFR" is used for these STOFS-3D-Atlantic SHEF files: stofs_3d_atl.tCCz.points.cwl.shef Where tCCz is forecast cycle: CC = 12 - The AWIPS header is changing from “TIBEP” to “TIBEA” in these STOFS-3D- Atlantic SHEF files: stofs_3d_atl.tCCz.points.cwl.shef Where tCCz is forecast cycle: CC = 12 - The coverage increases to north of the Aleutian Islands in the following files: stofs_2d_glo.tCCz.alaska.cwl.grib2 stofs_2d_glo.tCCz.alaska.htp.grib2 stofs_2d_glo.tCCz.alaska.swl.grib2 stofs_2d_glo.tCCz.alaska.f{hour}.grib2 Where {hour} = {0,1,2,3,...,180}, and tCCz is forecast cycle: CC = 00, 06, 12, and 18 - The coverage for Gulf of California is removed in the following files: stofs_2d_glo.tCCz.conus.west.cwl.grib2 stofs_2d_glo.tCCz.conus.west.htp.grib2 stofs_2d_glo.tCCz.conus.west.swl.grib2 stofs_2d_glo.tCCz.conus.west.f{hour}.grib2 Where {hour} = {0,1,2,3,...,180}, and tCCz is forecast cycle: CC = 00, 06, 12, and 18 NOAAPORT/Satellite Broadcast Network (SBN) Dissemination Changes: STOFS-2D-Global: - WMO headers: No changes - Data content: - SHEF: many stations along the U.S. East and West Coasts, Alaska, Hawaii, and Pacific Islands are added. - GRIB2: Alaska headed data increases coverage to north of the Aleutian Islands, and CONUS West headed data removes coverage for the Gulf of California. STOFS-3D-Atlantic: - WMO headers: - SHEF: WMO headed data “SXUS02 KWBM” is added for STOFS-3D-Atlantic. To deconflict with STOFS-2D-Global using the same headers, type source “HMIFR” is used in these data. - GRIB2: WMO headed data below is added for STOFS-3D-Atlantic. To deconflict with STOFS-2D-Global using the same headers, process ID “21” is used in these data (https://www.nco.ncep.noaa.gov/pmb/docs/on388/tablea.html) CONUS East Headers: ECIA88 KWBM ECIB88 KWBM ECIC88 KWBM ECID88 KWBM ECIE88 KWBM ECIF88 KWBM ECIG88 KWBM ECIH88 KWBM ECII88 KWBM ECIJ88 KWBM ECIK88 KWBM ECIL88 KWBM ECIM88 KWBM ECIN88 KWBM ECIO88 KWBM ECIP88 KWBM ECIQ88 KWBM ECIX88 KWBM ECIY88 KWBM Puerto Rico Headers: ECPA88 KWBM ECPB88 KWBM ECPC88 KWBM ECPD88 KWBM ECPE88 KWBM ECPF88 KWBM ECPG88 KWBM ECPH88 KWBM ECPI88 KWBM ECPJ88 KWBM ECPK88 KWBM ECPL88 KWBM ECPM88 KWBM ECPN88 KWBM ECPO88 KWBM ECPP88 KWBM ECPQ88 KWBM ECPX88 KWBM ECPY88 KWBM A consistent parallel feed of STOFS v2.1.7 data is available on the NCEP sites at the following URLs: https://nomads.ncep.noaa.gov/pub/data/nccf/com/stofs/para/ https://www.ftp.ncep.noaa.gov/data/nccf/com/stofs/para/ ftp://ftp.ncep.noaa.gov/pub/data/nccf/com/stofs/para/ https://para.nomads.ncep.noaa.gov/pub/data/nccf/noaaport/stofs_2d_glo / https://para.nomads.ncep.noaa.gov/pub/data/nccf/noaaport/stofs_3d_atl / NCEP urges all users to ensure their decoders can handle changes in content order, changes in the scaling factor component within the product definition section (PDS) of the GRIB files, and volume changes. These elements may change with future NCEP model implementations. NCEP will make every attempt to alert users to these changes before implementation. Any questions, comments or requests regarding this implementation should be directed to the contacts below. For questions concerning science changes, please contact: Greg Seroka Coastal Marine Modeling Branch Coast Survey Development Laboratory NOAA/NOS/Office of Coast Survey Silver Spring, MD gregory.seroka@noaa.gov For questions regarding the data flow aspects of these datasets, contact: Tony Salemi NCEP Central Operations Dataflow Team Lead (Acting) College Park, Maryland ncep.pmb.dataflow@noaa.gov National Service Change Notices are online at: https://www.weather.gov/notification/