GraphCast Operational IFS Reforecast API

GribStream Code: aiwpgraphcastifs

Official source: The CIRA and NOAA GSL AI Weather Prediction archive runs GraphCast Operational from ECMWF IFS analyses for reproducible community evaluation.

Current GribStream coverage: aiwpgraphcastifs begins with the May 27, 2025 00 UTC cycle and grows as new cycles arrive. That timestamp is the defined start of this GribStream series.

Experimental research availability: The registry warns that data may be missing and availability is not guaranteed; the public README says the data are provided as-is and documents earlier publication-timing and directory-structure changes. This evaluation dataset is not an official operational NOAA or ECMWF forecast. Do not make it the sole dependency for availability-sensitive systems: monitor forecasted_at freshness and keep an operational fallback dataset.

Version continuity: Each GribStream code is pinned to the current source-model version. A materially different upstream model version will receive a separate dataset code rather than being silently joined to this history.

Description

GraphCast Operational is a data-driven global model. AIWP runs this variant with IFS from ECMWF IFS analyses and selects a period beginning in January 2022 to avoid overlap with model training or fine-tuning.

The GraphCast Operational paper describes its design. GraphCast uses a graph neural network on a multi-scale mesh: it encodes the latitude-longitude state onto the mesh, advances the atmosphere by 6 hours, and decodes the result back to the global grid. Published results describe specific experiments and do not guarantee performance for this current archive.

The GraphCast Operational inventory covers 2 metre temperature, 10 metre wind, mean sea-level pressure and 6-hour precipitation, plus six upper-air variables on 13 pressure levels, including vertical velocity. These fields support analysis of large-scale circulation, thermal structure, moisture transport, and weather-system evolution.

The aiwpgraphcast variant uses the other initial-condition system. Comparing them helps study sensitivity to the starting state, but does not isolate model quality by itself: GFS and IFS are different analysis systems. This page covers IFS.

This is a deterministic research forecast, not an uncertainty product. Its precipitation field is a 6-hour accumulation. In the IFS-initialized product, the first two precipitation records are missing throughout the grid, so atmospheric fields begin at hour 6 and precipitation at hour 12. For operational decisions, compare it with current authoritative guidance. The team asks users to cite the AIWP archive paper.

Detail

• Archive begins: 2025-05-27
• Official AIWP dataset registry: https://registry.opendata.aws/aiwp/
• Key features:
  • Complete 1,440 by 721 global grid: 1,038,240 cells at 0.25 degree spacing.
  • 00 and 12 UTC cycles with forecast hours 6 through 240 at 6-hour intervals.
  • 11 source variable names and 83 exact selectors: 2 metre temperature, 10 metre wind, mean sea-level pressure and 6-hour precipitation, plus six upper-air variables on 13 pressure levels, including vertical velocity.
  • Published names, levels, float32 values, and units remain unchanged; the generated inventory documents every selector.
• Resolution: Regular global 0.25 degree grid with 1,440 longitudes by 721 latitudes.
• Temporal coverage: 00 and 12 UTC cycles; 6-hour steps through 240 hours, or 10 days.
• Primary uses: AI-model evaluation, initial-condition comparison, forecast verification, synoptic analysis, wind and temperature studies, cyclone research, and machine-learning benchmarks.

Related datasets

• The same model with the other initial-condition system
• GFS for NOAA operational global guidance
• IFS Oper for ECMWF operational global guidance

Parameters