GraphCast may have forecast Lee's landfall nine days ahead

DeepMind says a live GraphCast run on ECMWF's site forecast Lee's Nova Scotia landfall about nine days ahead; NHC records landfall 16 September 2023; no forecaster use of the run is documented.

AI system

System

GraphCast (Google DeepMind graph neural network weather model), experimental live run on ECMWF public charts

Model

GraphCast.

Release

Exact release not established.

Application developer

DeepMind

Role

GraphCast generated weather forecasts, including the projected path of Hurricane Lee.

Configuration

Researchers used the live GraphCast forecasts available through ECMWF.

Inputs and outputs

Not assessed

Autonomy

Not assessed

Workflow

GraphCast trained on decades of ERA5 reanalysis and run live from ECMWF initial conditions on ECMWF's experimental charts. A long-lived Cabo Verde hurricane whose track was, per NHC, easier than normal to forecast (low climatology-persistence errors). Vendor retrospective comparison of its own run against conventional models.

Human oversight

Not assessed

Relation to AI

The only sources for the nine-day Lee forecast are the maker's own blog and a news report quoting the maker's scientist. ECMWF's editorial confirms only that GraphCast ran experimentally on its charts. NHC's Lee report records exceptionally low official track errors without mentioning AI guidance. The AI output is therefore documented as a forecast, not as an input to any decision.

AI contribution

The only sources for the nine-day Lee forecast are the maker's own blog and a news report quoting the maker's scientist. ECMWF's editorial confirms only that GraphCast ran experimentally on its charts. NHC's Lee report records exceptionally low official track errors without mentioning AI guidance. The AI output is therefore documented as a forecast, not as an input to any decision.

Benefits

Outcome identifiers

Not assessed

Benefit

forecast Lee's Nova Scotia landfall about nine days ahead

Category

Improved Task Accuracy

Status

Not assessed

Beneficiary groups

People. Organizations. Society.

Beneficiaries

Not assessed

Reach

Not assessed

Distribution and access

Not assessed

Duration

Not assessed

Expected?

Yes

Costs and harms

Not assessed

Measurement

Studies

Not assessed

Study design

Not assessed

Measurement

Not assessed

Setting and sample

Not assessed

Measures

forecast Lee's Nova Scotia landfall about nine days ahead

Comparison

Assumed alternative: traditional physics-based forecasts of Hurricane Lee's landfall (DeepMind's own account)

Results

Assumed comparison. Reference: only locked in on Nova Scotia about six days in advance. Result: about nine days in advance.

Additional value from AI

Not assessed

Limitations

Not assessed

Denominators

Not assessed

Materials for replication

Not assessed

Money

Kind of value

Not assessed

Amount

Not assessed

Currency and prices

Not assessed

Period and unit

Not assessed

Realization

Not assessed

Recipients and payers

Not assessed

Gross or net

Not assessed

Included costs

Not assessed

Comparison

Not assessed

Method

Not assessed

Return and payback

Not assessed

People and places

Participants

Developer: DeepMind. Operator: ECMWF (experimental data-driven forecasts on its public charts pages).

Jurisdictions

Benefit: Long Island, southwestern Nova Scotia, Canada (landfall). Developer: United Kingdom. Operator: United Kingdom.

Ownership and control

Not assessed

Dependencies

Not assessed

Cross-border connections

Not assessed

Geopolitical implications

Not assessed

Follow-up

Conditions for replication

Independent verification of the specific nine-day run against the official track record (not found in any ECMWF or NHC document among the sources). Access to ECMWF initial conditions for the live run. A forecaster or authority actually consulting the AI run for it to become an attributable benefit.

Replication attempts

1 follow-up entries. Benefit recurred: 1.

Later findings

7 November 2024. An independent Uppsala University evaluation published 7 November 2024 confirmed GraphCast's general advantage over ECMWF's IFS HRES, including on near-surface temperature and wind extremes; it does not examine the Hurricane Lee forecast, and the NHC's March 2024 report on Lee names no AI model.

Availability

Not assessed

Institutional decision

Not assessed

Grounds

Not assessed

Action and result

Not assessed

Success criterion

Not assessed

Evidence

Source numbers

AIBD-0341-source-0001–0008

Citations

Numbered references below.

Language

Not assessed

Source relationships

Developer, Independent, Operator

Original evidence

Not assessed

Access and versions

Not assessed

Supported findings

Not assessed

Evidence strength

Not assessed

Missing evidence

Not assessed

Grades

Assessed benefits

People. Organizations. Society.

Depth

Not assessed

Reasons

People: No individual outcome is documented. Organizations: General benefit. No cited source documents a forecast office using the GraphCast Lee run in its products. Society: General benefit. No public-safety decision is linked to the run in any cited source.

Observed or intended

Not assessed

Rubric

Not assessed

Assessor and date

Not assessed

Alternative assessments

Not assessed

Fill

Independently studied

Entry details

Kind

Not assessed

Field

Weather forecasting / tropical cyclones. Public-sector meteorological service; AI research laboratory.

Purpose

Machine-learning global medium-range weather forecasting (10 days, 0.25 degree), including severe-event prediction such as tropical cyclone tracks. This forecast was that purpose.

Dates

Date basis unassessed: 2023 (precision unassessed). Updated: 22 October 2026.

Stage

Not assessed

Version

SHA-256: 9911fcda891b…

References

Other identifiers

Not assessed

Category mappings

Not assessed

Brief

Not assessed

Revisions

9 revisions. Latest: 22 October 2026.

Sources

  1. Peer-reviewed study Independent author

    Olivetti L, Messori G (2024). Do data-driven models beat numerical models in forecasting weather extremes? A comparison of IFS HRES, Pangu-Weather, and GraphCast. Geoscientific Model Development 17:7915-7962, doi:10.5194/gmd-17-7915-2024.

  2. Report Independent author

    Blake, E. and Nepaul, H. (2024). National Hurricane Center Tropical Cyclone Report: Hurricane Lee (AL132023), 5-16 September 2023. NOAA/NWS, 21 Mar 2024.

  3. Preprint Developer

    Lam, R., Sanchez-Gonzalez, A., Willson, M., et al. (2022/2023). GraphCast: Learning skillful medium-range global weather forecasting. arXiv:2212.12794 (published in Science, Nov 2023).

  4. News report Independent author

    Heikkilä, M. (2023). Google DeepMind's weather AI can forecast extreme weather faster and more accurately. MIT Technology Review, 14 Nov 2023.

  5. Press release Developer

    Google DeepMind (2023). GraphCast: AI model for faster and more accurate global weather forecasting. DeepMind blog, 14 Nov 2023.

  6. Press release Deployer

    Rabier, F. (2023). The AIFS is launched (editorial). ECMWF Newsletter No. 177, Autumn 2023.