ECMWF will stop experimental GraphCast and FourCastNet charts when AIFS v2 launches

ECMWF's implementation pages for IFS Cycle 50r1, AIFS Single v2, and AIFS ENS v2 now say that, as part of the May 12, 2026 upgrade, ECMWF will stop running its experimental Machine Learning model charts:

• Aurora
• FourCastNet
• GraphCast
• Pangu-Weather

We already covered the May 12 cutover in ECMWF sets May 12, 2026 for IFS Cycle 50r1 and AIFS v2. The important new detail is the explicit shutdown of those ECMWF experimental ML chart products.

What is changing at ECMWF

The same May 12 upgrade moves ECMWF's operational AI line forward:

• AIFS Single moves from v1.1 to v2
• AIFS ENS moves from v1 to v2
• both AIFS lines add a 10 hPa pressure level
• both add a new wave component/stream
• AIFS ENS v2 adds an operational data-driven wave ensemble stream

That means ECMWF is consolidating operational AI forecasting around AIFS Single and AIFS ENS, while the separate experimental chart models are being turned off.

Does this discontinue GribStream GraphCast or FourCastNet?

Not by itself.

The ECMWF pages are talking about ECMWF's own experimental Machine Learning charts. GribStream's GraphCast and FourCastNetGFS pages refer to NOAA/NCEP GFS-based datasets, not those ECMWF chart experiments.

So this ECMWF notice does not announce that GribStream's GraphCastGFS or FourCastNetGFS data stop on May 12.

If the NOAA/NCEP GraphCastGFS or FourCastNetGFS datasets are discontinued separately, GribStream would stop receiving new forecasts for the discontinued feed. We would keep serving historical forecasts for as long as the underlying files remain available through the AWS Open Data program.

It still matters because the names overlap. If you compare GribStream AI datasets against ECMWF's experimental ML chart products, that comparison set may disappear. If you use ECMWF AI guidance operationally, the replacement path is AIFS Single v2 and AIFS ENS v2, not the old experimental chart set.

What to watch

• The May 12, 2026 cutover for IFS 50r1, AIFS Single v2, and AIFS ENS v2
• Any ECMWF follow-up on exact chart/product retirement behavior
• Separate NOAA/NCEP or AWS Open Data notices for GraphCastGFS or FourCastNetGFS availability

For GribStream users, the safe assumption is: ECMWF's experimental ML charts are being retired, while NOAA/NCEP GraphCastGFS and FourCastNetGFS should be tracked through NOAA/AWS sources separately.

Sources

• ECMWF Implementation of IFS Cycle 50r1 page: https://confluence.ecmwf.int/display/FCST/Implementation%2Bof%2BIFS%2BCycle%2B50r1
• ECMWF Implementation of AIFS Single v2 page: https://confluence.ecmwf.int/display/FCST/Implementation%2Bof%2BAIFS%2BSingle%2Bv2
• ECMWF Implementation of AIFS ENS v2 page: https://confluence.ecmwf.int/display/FCST/Implementation%2Bof%2BAIFS%2BENS%2Bv2