This page indexes all NOAA models in this repository that are part of, are being consolidated into, or are being retired by the Unified Forecast System (UFS) — NOAA's community-based, coupled Earth-system modeling framework that is gradually replacing the patchwork of independently-developed operational systems NCEP has run for decades.
The goal of this index is to make a coherent programme visible. Right now UFS shows up across the repository as separate line items — RRFSv1 here, GFSv17 there, RTOFS v3.0 elsewhere, NAM retirement somewhere else — but they are all parts of the same consolidation effort, scheduled and sequenced together. This page exists to surface that coherence.
Last updated: July 2026.
UFS is a coupled Earth-system modeling framework developed jointly by NOAA, NCAR, the U.S. Navy, NASA, the broader research community, and external operational and academic partners. Its operational purpose is to consolidate NOAA's operational forecast suite — historically a collection of independently-developed systems with overlapping responsibilities and divergent infrastructure — into a single, modular framework where atmosphere, ocean, sea ice, waves, land, and atmospheric composition share a common code base, common couplers, and a common community development model.
NOAA's stated goal is to reduce the NCEP Production Suite from 21 operational systems to 8 under UFS. The 21 → 8 figure is NOAA's own framing and refers specifically to operational NCEP systems; it is not a claim about every model in this repository. What follows is the subset of those changes that affect publicly downloadable systems documented here.
The core architectural pieces of UFS are:
- Atmosphere: FV3 (Finite-Volume Cubed-Sphere) in current and near-term configurations; MPAS (Model for Prediction Across Scales) is the planned successor for the convection-allowing regional component (RRFSv2)
- Ocean: MOM6 (Modular Ocean Model 6)
- Sea ice: CICE6 (Community Ice CodE)
- Waves: WAVEWATCH III
- Land: Noah-MP
- Atmospheric composition: CMAQ (Community Multiscale Air Quality) embedded within UFS, replacing the legacy offline-coupled GFS-CMAQ chain
- Coupler: CMEPS (Community Mediator for Earth Prediction Systems), built on the NUOPC/ESMF infrastructure
- Data assimilation: JEDI (Joint Effort for Data assimilation Integration) — the new community DA framework being introduced in stages, replacing legacy GSI for several variables in GFSv17
For external technical documentation of UFS itself, see the UFS Community site at https://ufscommunity.org/. This page documents UFS from the operational catalog perspective: what's running, what's being retired, and what users need to switch to.
UFS is not arriving as a single cutover. Components are being absorbed into UFS one at a time, on a multi-year schedule, with each operational replacement triggering specific retirements. The rough sequencing is:
- 2023 — HAFS replaces HWRF and HMON. The first major UFS-based operational system, replacing both legacy hurricane models simultaneously. HAFS uses FV3 atmosphere with online CMEPS coupling to ocean and waves.
- 2024 — AQM v7 migrates to UFS-based architecture. The atmospheric composition component of NAQFC moved from offline-coupled GFS-CMAQ to UFS-based online-coupled atmosphere-chemistry.
- 2025 — RTOFS v2.5 deployed alongside HAFSv2.1. RTOFS itself stays on HYCOM in v2.5; the UFS-relevant connection is that HAFSv2.1 is initialized from RTOFS v2.5, tightening the operational dependency between these systems.
- October 6, 2026 — RRFSv1 + REFS replace NAM, NAM Nest, HiresW (except Guam), HREF, NARRE, and SREF. This is the largest wave of retirements and the first time UFS replaces multiple regional systems simultaneously. The set is scheduled by NWS SCN 26-47 (termination) and SCN 26-48 (RRFS/REFS implementation), both updated July 6, 2026, for the 12 UTC cycle on October 6, with the standard CWD/ECE contingency for postponement. The July 6 update is the second slip, moving the date from August 31 to October 6 and decoupling the real-time parallel feed to on or about August 11, 2026. Notably, SREF is included in this wave — it was previously expected to persist into the second wave under RRFSv2, but NBM v5.0's elimination of SREF as an input earlier in 2026 removed the last major operational consumer, and the SCN folded SREF retirement into the RRFSv1 cutover.
- Targeted October 2026 (proposed) — GFSv17 + GDASv17. GFS transitions from atmosphere-centric to a fully coupled Earth-system model with MOM6 ocean, CICE6 sea ice, and WAVEWATCH III waves all coupled via CMEPS. GDAS introduces JEDI-based DA for ocean, sea ice, and snow.
- Proposed (March 2026 PNS) — RTOFS v3.0. Replaces HYCOM with MOM6 and CICE4 with CICE6, aligning RTOFS with the rest of the UFS component stack.
- Future — RRFSv2 (MPAS-based) replaces HRRR, RAP, and NAM 12 km. No formal retirement notification yet for these systems; they are expected to follow once RRFSv2 is operational.
Each of these has slipped at least once relative to its original target date, and further slippage should be expected. The pattern of slippage is itself worth knowing about — UFS is a major undertaking and conservative scheduling is the norm rather than the exception. RRFSv1/REFS itself was originally targeted for "early 2026" under PNS 25-41, then to August 31, 2026 under SCN 26-48, before slipping again to October 6, 2026 in the July 6, 2026 update.
These systems already run on UFS infrastructure as of May 2026.
- Operational since: June 2023 (v1.0); current version v2.1 (July 2025)
- UFS components used: FV3 atmosphere, HYCOM ocean (transitioning), WAVEWATCH III waves, CMEPS coupler
- Replaced: HWRF and HMON (both retired 2023)
- Notes: First major UFS-based operational system. HAFS runs only when active tropical cyclones exist; supports basins worldwide (NATL, EPAC, CPAC, WPAC, NIO, SH).
- Operational since: May 2024 (v7.0.7 — UFS-based architecture introduced)
- UFS components used: UFS-based online-coupled atmosphere-chemistry embedding CMAQ v5.2.1
- Replaced: Offline-coupled GFS-CMAQ chain used in AQMv5 and AQMv6
- Notes: Transition from three separate domains (CONUS, AK, HI at ~12 km) to a single unified North American domain at 13 km.
These are the most operationally significant UFS transitions that are either imminent or in late-stage pre-operational status as of May 2026.
- Status: Scheduled for operational implementation October 6, 2026 at 12 UTC, subject to CWD/ECE contingency
- UFS components used: FV3 dynamical core (v1); MPAS planned for v2
- Replaces (all retiring on the same day):
- NAM (12 km parent and all 3 km nests including fire weather)
- NAM Nest
- HREF (replaced by REFS)
- HiresW (CONUS, Alaska, Hawaii, Puerto Rico domains — see Status and retirement for the surviving exception)
- SREF (not in this repository) — replaced by REFS
- NARRE (not in this repository) — replaced by REFS
- NAM MOS (not in this repository) — retired alongside NAM
- Authority: NWS SCN 26-48 (implementation; May 12, 2026, updated July 6, 2026); retirements under companion SCN 26-47 (termination; updated July 6, 2026). The retirement set was originally proposed in NWS PNS 25-41 (June 26, 2025).
- Pre-implementation real-time feed: On or about August 11, 2026, NOAA will publish parallel RRFS and REFS data on NOMADS at
/nccf/com/rrfs/para/and/nccf/com/refs/para/. Post-implementation paths (from October 6, 2026) are/nccf/com/rrfs/prod/and/nccf/com/refs/prod/. - Domains: CONUS, Alaska (3 km), Hawaii, Puerto Rico (2.5 km), plus a separate 1.5 km fire-weather RRFS domain
- Deterministic forecast cadence: RRFS runs hourly. The 00/06/12/18 UTC synoptic cycles run to 84 hours; the other 20 hourly cycles run to 18 hours.
- Ensemble forecast cadence: REFS runs to 60 hours, 4× daily (00/06/12/18 UTC) for all domains. RRFS itself produces 5 ensemble members for those four cycles; REFS combines those with the 6-hour-old RRFS deterministic and ensemble cycles. For the CONUS and Alaska REFS domains, the HRRR contributes two additional members (current and 6 h old) — making HRRR an explicit input to a UFS-era operational system even though HRRR itself is not retired in this wave.
- HREF → REFS comparison: REFS extends forecasts to 60 hours (HREF was 48 hours); REFS provides 4 cycles daily for all regions, including non-CONUS domains (HREF only ran twice daily for AK, HI, and PR).
- Status: Proposed for October 2026; public comment period open through May 2026
- UFS components used: FV3 atmosphere at C1152 (~9 km, up from C768/~13 km), MOM6 ocean, CICE6 sea ice, WAVEWATCH III waves, CMEPS coupler, JEDI DA for ocean/sea ice/snow
- Replaces: Current atmosphere-centric GFS v16 and GDAS v16
- Authority: NWS PNS 26-29 (April 15, 2026), with companion product-removal notice PNS 26-30 (April 16, 2026)
- Notes: Largest single UFS transition planned. Pre- and post-v17 forecast comparisons should be treated as separate model eras for validation, backtesting, and climatology.
RTOFS Global — v3.0
- Status: Proposed (PNS 26-17, March 2026); not yet operationally scheduled
- UFS components used: MOM6 ocean (replacing HYCOM), CICE6 sea ice (replacing CICE4)
- Replaces: Current RTOFS v2.5 HYCOM/CICE4 system
- Notes: RTOFS v3.0 represents alignment with the UFS ocean and ice model stack used elsewhere (MOM6 + CICE6 are also used in GFSv17). HAFS (which initializes from RTOFS) will inherit MOM6/CICE6 ocean state in due course.
- Operational since: May 5, 2026 (originally targeted April 15; slipped to April 23, then April 30, with the April 30 attempt deferred under the SCN's CWD/ECE contingency)
- UFS relationship: NBM is not itself a UFS model — it's a statistical post-processing system. But v5.0 added UFS-relevant inputs:
- Higher-resolution GDPS (15 km) and REPS (10 km) inputs (these are Canadian, not UFS-related)
- AIGFS (NOAA's operational AI global model) added as input for temperature, wind speed, and QPF
- ECAIFS (ECMWF's AI/IFS hybrid) similarly added
- SREF eliminated as an input — this is operationally significant because it removed the last major downstream consumer of SREF, and the August 31, 2026 SCN folded SREF retirement into the first wave alongside RRFSv1/REFS rather than holding it for RRFSv2
- Notes: NBM's evolving input set tracks the UFS rollout indirectly. As GFSv17, RRFSv1, and REFS go operational, expect future NBM upgrades to incorporate them and remove their predecessors.
These systems are scheduled for retirement on October 6, 2026 at 12 UTC, on the same cycle that brings RRFSv1 and REFS into operations. The retirement set was originally proposed in NWS PNS 25-41 (June 26, 2025); the retirements are scheduled by NWS SCN 26-47 (termination) and RRFS/REFS implementation by companion SCN 26-48, both updated July 6, 2026 (which moved the date from August 31 to October 6). Subject to the standard CWD/ECE contingency.
| Retiring system | Replacement | Notes |
|---|---|---|
| NAM | RRFSv1 (CONUS 3 km, post-processed grids) | Full retirement: 12 km parent, all 3 km nests, fire-weather nest |
| NAM Nest | RRFSv1 | All convection-allowing nests retired |
| HREF | REFS | Full replacement; REFS extends to 60 h, runs 4× daily for all regions |
| HiresW CONUS, AK, HI, PR | RRFSv1 (3 km CONUS/AK; 2.5 km HI/PR) | Guam domain explicitly preserved — see Status and retirement |
| SREF (not in repo) | REFS | SCN-confirmed first-wave retirement; previously expected to persist into the second wave under RRFSv2 |
| NARRE (not in repo) | REFS | NARRE's hourly 12-h ensemble guidance replaced by REFS's 60-h forecasts |
| NAM MOS (not in repo) | Post-processed RRFS-based statistical guidance | Retired alongside NAM |
These systems are publicly signaled (through NOAA roadmap documents) but have no formal retirement notification as of May 2026. They are expected to be retired when RRFSv2 (MPAS-based) is operational, which has no announced date.
| Retiring system | Replacement | Status |
|---|---|---|
| HRRR | RRFSv2 (MPAS) | Expected; no formal SCN |
| RAP | RRFSv2 (MPAS) | Expected; no formal SCN |
| NAM 12 km (parent domain only) | RRFSv2 large-domain configuration | Expected |
These represent the second major retirement wave under UFS. Users with operational dependencies on HRRR or RAP should plan for migration to RRFS but should not expect this to happen in 2026.
Note that SREF, which was previously listed in this second-wave table, was moved to the first wave — its retirement is now formally scheduled for October 6, 2026 under SCN 26-47.
NOAA's stated goal of reducing the NCEP Production Suite from 21 to 8 reflects multiple consolidations happening simultaneously. The table below shows which legacy systems collapse into which UFS components, restricted to systems documented in this repository.
| UFS component (target) | Legacy systems consolidated |
|---|---|
| GFSv17 (global atmosphere + ocean + ice + wave) | GFS (v16); GDAS (v16); historically separate ocean and wave initialization paths |
| RRFSv1 (regional convection-allowing deterministic) | NAM, NAM Nest, HiresW (except Guam) |
| REFS (regional convection-allowing ensemble) | HREF, NARRE, SREF |
| HAFS (tropical cyclone) | HWRF, HMON (already retired 2023) |
| AQM v7 within NAQFC (air quality) | Pre-v7 offline-coupled GFS-CMAQ chain |
| RTOFS v3.0 (global ocean) | RTOFS v2.5 (HYCOM); historically separate Navy/NOAA ocean initialization paths |
| GEFS + REFS + RRFSv2 ensemble (future) | GEFS (continues), HREF, NARRE, SREF |
| RRFSv2 (MPAS, future) | HRRR, RAP, NAM 12 km |
The remaining UFS components in the 8-system target include atmospheric ensemble systems and specialized non-NWP services that are outside this repository's scope.
Some operational models do not themselves run on UFS but incorporate UFS-derived inputs:
NBM is a statistical post-processor, not a UFS component. But as UFS systems become operational, NBM ingests their output and discontinues legacy inputs. NBM v5.0 (May 2026) eliminated SREF as an input and added AIGFS — a pattern that will continue as RRFSv1, REFS, and GFSv17 go operational.
HAFS is initialized from RTOFS, so RTOFS upgrades flow into HAFS in subsequent cycles. When RTOFS migrates to MOM6/CICE6 in v3.0, HAFS's ocean initialization will follow.
HRRR contributes two members (current and 6 h old cycles) to the CONUS and Alaska REFS domains. HRRR is not itself a UFS system and is not retired in the first wave; this makes HRRR an explicit operational input to a UFS-era ensemble during the period between RRFSv1 implementation and the eventual RRFSv2 transition that retires HRRR.
- Internal NCEP infrastructure systems that are not publicly distributed (workflow management, post-processing chains)
- Non-NCEP UFS users (research configurations, university-run UFS instances)
- Detailed UFS architecture — for that, see https://ufscommunity.org/
- Atmospheric ensemble systems unrelated to UFS — GEFS continues to run, but its UFS-relevant changes are limited to coupling with GFSv17's analysis system
- AI components within UFS — these may emerge in future versions but as of May 2026 are not part of operational UFS components. See AI_MODELS.md for the AI-specific index.
For lifecycle events (implementation dates, version numbers, slippage), see STATUS.md. UFS-related items in STATUS.md are kept brief, with detailed UFS context maintained here.
For the broader Copernicus and ECMWF programmes (which are UFS's European peers but operate independently), see COPERNICUS.md and the various ECMWF entries in models/.
If a UFS-related change is announced — a new SCN, a slippage, a new component integration, or a new retirement notification — please update both this file and STATUS.md with consistent dates and link to the authoritative source. The UFS rollout is multi-year and active; this page will need ongoing maintenance.