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NOUS41 KWBC 031325
PNSWSH
SERVICE CHANGE NOTICE 26-51
NATIONAL WEATHER SERVICE HEADQUARTERS SILVER SPRING, MD
925 AM EDT WED JUN 3 2026
TO: SUBSCRIBERS:
-NOAA WEATHER WIRE SERVICE
-EMERGENCY MANAGERS WEATHER INFORMATION NETWORK
-NOAAPORT
OTHER NWS PARTNERS AND EMPLOYEES
FROM: COREY ALLEN
CHIEF, COAST SURVEY DEVELOPMENT LABORATORY
NOS/OFFICE OF COAST SURVEY
SUBJECT: UPGRADE OF THE SURGE AND TIDE OPERATIONAL FORECAST
SYSTEM (STOFS) TO VERSION 3.1 EFFECTIVE JULY 7, 2026
EFFECTIVE ON OR ABOUT JULY 7, 2026, BEGINNING WITH THE 1200
UNIVERSAL COORDINATED TIME (UTC) CYCLE, THE NATIONAL CENTERS FOR
ENVIRONMENTAL PREDICTION (NCEP) CENTRAL OPERATIONS (NCO) WILL
UPGRADE THE SURGE AND TIDE OPERATIONAL FORECAST SYSTEM (STOFS)
TO VERSION 3.1.0. THIS IMPLEMENTATION MAY BE DELAYED IF THERE
IS DECLARATION OF EITHER AN ENHANCED WEATHER SITUATION OR
CRITICAL WEATHER DAY.
STOFS V3.1.0 REPRESENTS A MAJOR 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 FOR STOFS-2D-GLOBAL (ADCIRC-BASED) INCLUDE:
- 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 THAT
BOTH STATION AND GRIDDED OUTPUT IS BIAS CORRECTED.
- ADDITION OF A FEW STATIONS TO THE STATION OUTPUT, AS
REQUESTED BY NATIONAL WEATHER SERVICE FORECAST OFFICES: BOGUE
SOUND AT EMERALD ISLE, NC; WHITE OAK RIVER AT SWANSBORO, NC;
KINGS BAY MSF PIER, GA; AND TEMCO KALAMA TERMINAL, WA.ALSO,
SOME REDUNDANT STATIONS ARE REMOVED FROM THE OUTPUT: DUCK, NC;
FORT POINT, NH; MONEY POINT, VA; AND SPRINGMAID PIER, SC. SOUTH
AMBOY, NJ WAS REMOVED AS IT IS NO LONGER ACTIVE AND S AMBOY
RARITAN RIVER, NJ IS THE ACTIVE STATION IN THAT AREA. FINALLY,
NAPLES BAY, NORTH, FL HAS AN UPDATED NOS ID FROM 8725110 TO
8725114.
MODEL UPGRADES FOR STOFS-3D-ATLANTIC (SCHISM-BASED) INCLUDE:
- 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 NETCDF OUTPUT WILL NOW BE REFERENCED TO LOCAL
MEAN SEA LEVEL (LMSL) (NO LONGER NAVD88), WHILE GRIDDED OUTPUT
WILL REMAIN REFERENCED TO XGEOID20B. STATION SHEF OUTPUT WILL
REMAIN REFERENCED TO MEAN LOWER LOW WATER (MLLW).
- ADDITION OF A FEW STATIONS TO THE STATION OUTPUT, AS
REQUESTED BY NATIONAL WEATHER SERVICE FORECAST OFFICES: BOGUE
SOUND AT EMERALD ISLE, NC; WHITE OAK RIVER AT SWANSBORO, NC; AND
KINGS BAY MSF PIER, GA. ALSO, SOME REDUNDANT STATIONS ARE
REMOVED FROM THE OUTPUT: DUCK, NC; FORT POINT, NH; MONEY POINT,
VA; AND SPRINGMAID PIER, SC. SOUTH AMBOY, NJ WAS REMOVED AS IT
IS NO LONGER ACTIVE AND S AMBOY RARITAN RIVER, NJ IS THE ACTIVE
STATION IN THAT AREA. FINALLY, NAPLES BAY, NORTH, FL HAS AN
UPDATED NOS ID FROM 8725110 TO 8725114.
LASTLY, A COMPONENT FOR THE PACIFIC CALLED STOFS-3D-PACIFIC IS
BEING ADDED, WHICH WILL USE THE SCHISM MODEL CORE. THIS
COMPONENT WILL 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.
OUTPUT CHANGES FOR NCEP NOMADS WEB SERVICES
A. FILE ADDITIONS:
THE BELOW ARE ADDITIONAL FILES BEING SENT TO NCEP NOMADS FOR
STOFS-2D-GLOBAL.
STOFS_2D_GLO.TCCZ.FIELDS.CWL.MAXELE.NC
STOFS_2D_GLO.TCCZ.FIELDS.CWL.MAXELE.NOANOMALY.NC
STOFS_2D_GLO.TCCZ.POINTS.CWL.NOANOMALY.NC
STOFS_2D_GLO.TCCZ.FIELDS.CWL.NOANOMALY.NC
THESE ARE THE ADDITIONAL FILES FOR STOFS-3D-PACIFIC:
STOFS_3D_PAC.T12Z.FIELD2D_NHHH1_HHH2.NC
STOFS_3D_PAC.T12Z.FIELD2D_FHHH1_HHH2.NC
STOFS_3D_PAC.TCCZ.FIELDS.OUT2D_NHHH1_HHH2.NC
STOFS_3D_PAC.TCCZ.FIELDS.OUT2D_FHHH1_HHH2.NC
STOFS_3D_PAC.TCCZ.{NCAST,FCAST}.STATION.PROFILE.NC
STOFS_3D_PAC.TCCZ.POINTS.CWL.TEMP.SALT.VEL.NC
STOFS_3D_PAC.TCCZ.POINTS.CWL.SHEF
STOFS_3D_PAC.TCCZ.FIELDS.CWL.MAXELE.NC
STOFS_3D_PAC.TCCZ.ALASKA.F{HOUR}.GRIB2 (WHERE {HOUR}={000-048})
STOFS_3D_PAC.TCCZ.ALASKA.CWL.GRIB2
STOFS_3D_PAC.TCCZ.CONUS.WEST.F{HOUR}.GRIB2 (WHERE {HOUR}={000-
048})
STOFS_3D_PAC.TCCZ.CONUS.WEST.CWL.GRIB2
STOFS_3D_PAC.TCCZ.GUAM.F{HOUR}.GRIB2 (WHERE {HOUR}={000-048})
STOFS_3D_PAC.TCCZ.GUAM.CWL.GRIB2
STOFS_3D_PAC.TCCZ.HAWAII.F{HOUR}.GRIB2 (WHERE {HOUR}={000-048})
STOFS_3D_PAC.TCCZ.HAWAII.CWL.GRIB2
STOFS_3D_PAC.TCCZ.NORTHPACIFIC.F{HOUR}.GRIB2 (WHERE {HOUR}={000-
048})
STOFS_3D_PAC.TCCZ.NORTHPACIFIC.CWL.GRIB2
(WHERE {NHHH1_HHH2}={N001_012,N013_024},
{FHHH1_HHH2}={F001_012,F013_024,F025_036,F037_048}, AND
WHERE TCCZ IS FORECAST CYCLE: CC = 12)
B. TIMELINESS CHANGES:
FOR STOFS-2D-GLOBAL, STOFS_2D_GLO.T00Z.POINTS.CWL.NC (WHERE TCCZ
IS FORECAST CYCLE: CC = 00,06,12,18) WILL BE AVAILABLE ABOUT 15
MINUTES EARLIER. ALL OTHER STOFS-2D-GLOBAL FILES WILL BE
AVAILABLE AT ABOUT THE SAME TIME AS V2.1.
ALL STOFS-3D-ATLANTIC FILES WILL BE AVAILABLE AT ABOUT THE SAME
TIME AS V2.1.
C. FILE SIZE CHANGES:
THE REFINEMENTS PERFORMED ON THE STOFS-3D-ATLANTIC MESH CHANGE
THE FOLLOWING STOFS-3D-ATLANTIC FILE SIZES:
STOFS_3D_ATL.T12Z.FIELD2D_NHHH1_HHH2.NC
STOFS_3D_ATL.T12Z.FIELD2D_FHHH1_HHH2.NC
STOFS_3D_ATL.TCCZ.FIELDS.OUT2D_NHHH1_HHH2.NC
STOFS_3D_ATL.TCCZ.FIELDS.OUT2D_FHHH1_HHH2.NC
STOFS_3D_ATL.TCCZ.CONUS.EAST.CWL.GRIB2
STOFS_3D_ATL.TCCZ.PUERTORI.CWL.GRIB2
(WHERE {NHHH1_HHH2}={N001_012,N013_024}, AND
{FHHH1_HHH2}={F001_012,F013_024,F025_036,F037_048,F049_060,F061_
072,F073_084,F085_096})
WHERE TCCZ IS FORECAST CYCLE: CC = 12
A CONSISTENT PARALLEL FEED OF DATA IS AVAILABLE ON THE NCEP
HTTPS SITES AT THE FOLLOWING URLS:
HTTPS://NOMADS.NCEP.NOAA.GOV/PUB/DATA/NCCF/COM/STOFS/PARA/
HTTPS://NOMADS.NCEP.NOAA.GOV/PUB/DATA/NCCF/COM/PARA/NOAAPORT/STO
FS_2D_GLO/
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:
MARGARET CURTIS
NWS CENTRAL OPERATIONS HPC DATAFLOW TEAM LEAD
COLLEGE PARK, MARYLAND
NCEP.PMB.DATAFLOW@NOAA.GOV
NATIONAL SERVICE CHANGE NOTICES ARE ONLINE AT:
WWW.WEATHER.GOV/NOTIFICATION/
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