IFS Cycle 50r1 forecast production is currently running in parallel with the existing operational production. 
The details of this new model cycle (IFS Cy 50r1) are outlined on the Implementation of IFS Cycle 50r1 page. As it comes with substantial changes to data, configuration requirements and file naming, we strongly encourage all real-time users to test the data.

AIFS Single V2 and AIFS ENS V2 will be implemented on the same day as IFS Cycle 50r1. You can test the data in a similar way. The AIFS Single V2 and AIFS ENS V2 production is also running in parallel with the existing operational production. The details of these new models (AIFS Single V2 and AIFS ENS V2) are outlined on the Implementation of AIFS Single v2 and Implementation of AIFS ENS v2 pages. 

This page explains the testing process and the actions the users need to take to prepare. 

The Release Candidate Phase for IFS started on 19 Feb 2026. The first cycle available in XDISS was 12Z 18 Feb 2026. File retention duration in XDISS is approximately 5 days. The RCP will allow a test period of at least two months. 

The Release Candidate Phase for AIFS started on 14 April 2026.

To support testing of the new data, a dedicated test environment has been established, which generates IFS Cycle 50r1 and AIFS Single V2 and AIFS ENS V2 test data for all users. Users with access to the operational PREd and ECPDS are also able to access these test environments.

These include:

• a test PREd (TPREd, esuite: https://products.ecmwf.int/esuite/requirements/)
• a test ECPDS (XDISS: https://xdiss-monitor.ecmwf.int/)

How To Test 

Depending on the Service Package held, the process for testing the new data will vary.

All users wishing to receive IFS Cycle 50r1 test data regardless of Service Package, must set up an IFS Cycle 50r1 test host.

Setting up a test host

1. Complete the RCP 50r1 - Test System User Details form, providing details of the host configuration for the IFS Cycle 50r1 test data.

2. Submission of the form will create a ticket with the Data Support team, who will make contact to set up or confirm the host configuration for the test data.

3. Data Support will then send a test file to verify the connection.

Further steps for testing will depend on the specific Service Package held by the user, as outlined below:

Basic + Bronze + Research Users

As Basic/Bronze/Research users do not have access to TPREd or XDISS, all 50r1 test changes to data requirements will be managed by the Data Support team.

1. A test batch of data will be manually pushed to the users test host for review.
2. If the user is satisfied, confirmation should be provided via the ticket. This will enable the Data Support team to mark the feeds as “Ready to migrate.”
3. If operational data requirements are modified prior to the IFS Cycle 50r1, AIFS Single V2 and AIFS ENS V2 implementation, the process will need to be repeated to ensure that user is prepared for the updated requirements on Implementation day.

Silver + Gold + Member/Cooperating State Users

As a Silver/Gold or MS/CS user, access is available to

• TPREd: https://products.ecmwf.int/esuite/requirements/ and
• XDISS: https://xdiss-monitor.ecmwf.int

If access is not available, please contact the Data Support team via the relevant ticket.

As part of the preparation for testing, ECMWF have already adjusted all data requirements in the test PREd (TPREd) to ensure compatibility with the Cycle 50r1 upgrade for IFS data and AIFS Single V2 and AIFS ENS V2 for AIFS data. Please see the below section 'Key Configuration Changes' for the changes that have been applied.

1. With access to both applications, users are able to make changes to their data requirements in TPREd and manually push test data to themselves via XDISS.
   Please see instruction here on how to do a manual push: https://www.ecmwf.int/en/forecasts/documentation-and-support/data-delivery/manage-your-data-transmission-ecpds

   
   

2. Once satisfied with the IFS Cycle 50r1, AIFS Single V2 and AIFS ENS V2 test data, users must mark the feeds in TPREd as “Ready to Migrate” by switching the toggle (located in the top-right corner of the interface) to ON.
   This action confirms that the TPREd feeds have been tested and are satisfactory to become the operational feeds on the day of implementation. The toggle may be switched off again, and further changes can be made to the feed, until the end of the testing phase.

   
   

3. Users should note that if changes are made to their operational feeds (PREd) during this period, those changes will need to be replicated in the test PREd in order to retain them.

   
   

4. If the “Ready to Migrate” toggle is not enabled, ECMWF will retain the user’s current operational PREd requirements and apply only mandatory system changes on Implementation day.

Key Configuration Changes for IFS

More changes may apply to your file naming and data streams - please see here for more details: Data streams and types to be discontinued in IFS cycle 50r1 and user impact + Dissemination file-naming changes from IFS Cycle 49r1 to 50r1

Key Configuration Changes for AIFS

FAQs