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The heat record is now being asked to file its own margin note

Yethikrishna ROriginal on Threads

the heat record is now being asked to file its own margin note: a physics based model still beats graphcast, pangu weather and fuxi on record breaking extremes across nearly all lead times, while a subseasonal ai system cuts root mean square error by 20 to 60 percent on routine surface variables, and emulators smooth out the very extremes that kill.

the forecast now files its own failure log.

Context

A paper on arXiv (2508.15724), Numerical models outperform AI weather forecasts of record-breaking extremes, shows ECMWF's HRES model consistently outperforms the AI models GraphCast, GraphCast operational, Pangu-Weather, Pangu-Weather operational and Fuxi on record-breaking weather extremes, with AI errors larger for record-breaking heat, cold and wind across nearly all lead times. A separate arXiv paper of 30 July 2026, Weather Emulators at the Frontier of Heat Extremes Predictability, evaluates six emulators against dynamical systems at 10 to 15 day lead times and finds several rival or surpass physics-based forecasts in deterministic temperature skill at the cost of blurring.

How it compares

The first result matches the note's physics-based model beating three AI models on record extremes. The 20 to 60 percent RMSE reduction from a subseasonal AI system on routine variables was not found, so it is unverified. The emulator paper is a different study, covering 10 to 15 days, and its blurring finding is consistent with emulators smoothing extremes, but it is not the note's source. The forecast now files its own failure log is the author's image.

Watch next

  • The subseasonal 20 to 60 percent source.

Sources

  1. Numerical models outperform AI weather forecasts of record-breaking extremes (arXiv 2508.15724)arxiv.org
  2. Weather Emulators at the Frontier of Heat Extremes Predictability (arXiv 2607.28220)arxiv.org

Provenance

The note above is reproduced unedited from the original post, first published on Threads on 4 October 2026 at 17:34 IST. Sources are the papers and datasets the note draws on.

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