NOAA AIGEFS ensemble forecasts are now available in GribStream

GribStream now serves NOAA's AI Global Ensemble Forecast System through two new API datasets:

• AIGEFS Surface, code aigefssfc
• AIGEFS Pressure, code aigefspres

NOAA implemented AIGEFS v1.0 on December 17, 2025 as part of its operational AI-GFS family, alongside deterministic AIGFS Surface, AIGFS Pressure, and the HGEFS hybrid ensemble. NOAA's service-change notice describes AIGEFS as a 31-member GraphCast-based global AI ensemble. NOAA/NCEP technical documentation describes the broader AI-GFS work as GraphCast-based guidance developed with NOAA research laboratories and the Earth Prediction Innovation Center.

Why AIGEFS matters

AIGEFS gives forecast systems a member-level AI ensemble to compare against deterministic AI forecasts and physics-based ensembles such as GEFS. That is useful when the question is not just "what is the forecast?" but "how much scenario spread is there across plausible AI forecasts?"

The two GribStream datasets expose members 0 through 30, with 00, 06, 12, and 18 UTC cycles and 6-hour forecast steps out to 384 hours on a 0.25 degree global grid.

Dataset coverage

aigefssfc is the member-level near-surface dataset. It includes wind, temperature, humidity, pressure, and precipitation signals for point forecasts, renewable-energy ranges, route-risk screening, and scenario dashboards.

aigefspres is the member-level upper-air dataset. It includes geopotential height, wind, temperature, humidity, and vertical velocity on standard pressure levels from 50 mb through 1000 mb. Use it when spread in steering flow, thermal structure, moisture layers, or vertical motion matters.

The existing deterministic AIGFS datasets also now read from NOAA's EAGLE AWS Open Data archive. That matters because the public EAGLE archive can accumulate history over time, while the operational NOMADS feed is designed as a short current-data window. For customers, this means AIGFS history in GribStream can grow with the NOAA public archive instead of being limited to only the last few days of operational output.

Requests use the same members field as other GribStream ensemble datasets:

{
  "fromTime": "2026-05-08T00:00:00Z",
  "untilTime": "2026-05-09T00:00:00Z",
  "coordinates": [{ "lat": 40.7128, "lon": -74.0060 }],
  "members": [0, 10, 20, 30],
  "variables": [
    { "name": "TMP", "level": "2 m above ground" },
    { "name": "UGRD", "level": "10 m above ground" },
    { "name": "VGRD", "level": "10 m above ground" }
  ]
}

HGEFS is part of NOAA's operational AI-GFS family, but it is not included in this GribStream release because the current NOAA EAGLE archive check did not show the HGEFS product alongside AIGFS and AIGEFS.

Sources:

• NOAA EAGLE AWS Open Data registry: https://registry.opendata.aws/noaa-nws-graphcastgfs-pds/
• NOAA EAGLE S3 bucket: https://noaa-nws-graphcastgfs-pds.s3.amazonaws.com/index.html
• NCEP AIGFS products: https://www.nco.ncep.noaa.gov/pmb/products/aigfs/
• NCEP AIGEFS products: https://www.nco.ncep.noaa.gov/pmb/products/aigefs/
• NWS Service Change Notice 25-89: https://www.weather.gov/media/notification/pdf_2025/scn25-89_AIGFS_AIGEFS_and_HGEFS.pdf
• NOAA/NCEP Office Note 521: https://doi.org/10.25923/xd3y-wy31