ECMWF Council at its 96th session in June 2020, agreed to make available Tropical Cyclone tracks (TC tracks) from the 06/18 UTC forecast cycles as WMO essential products. 

While ECMWF is evaluating the impact of these tracks on the corresponding cycles, test data has been made available for download.

Access to test data

TC tracks test files are available for download in BUFR4 format from:

Test data files are available in real-time at the corresponding sub-directories:



Notice: The number of tracks identified in the 06/18 cycles is lower due to the shorter forecast range available in these cycles (up to step 90 for HRES and 144 for ENS)

Updates to the BUFR headers

With the introduction of the TC tracks from the 06/18 UTC forecast cycles, an inconsistency in the encoding of the BUFR headers has been corrected.  The ensembleForecastType key (BUFR descriptor 001092) now contains the correct information for the different member forecasts (key ensembleMemberNumber, BUFR descriptor 001091), including situations where only one member is present, as described in the table:

BUFR Descriptor 001091
ecCodes key = ensembleMemberNumber

BUFR Descriptor 001092
ecCodes key = ensembleForecastType

ENS control511
ENS perturbed member1 - 50255 (MISSING)

A MISSING value may be reported by the decoding software as  'null', "missing value" or 2147483647.

See WMO=33 code-flag table#CF_001092 (TYPE OF ENSEMBLE FORECAST).

The updates to the BUFR headers will also be applied to the 00 and 12 UTC TC tracks once released in production.

Release Date

ECMWF will continue to test these products. Further notice will be provided for operational implementation.

Once in production, data via dissemination and graphical products will also be made available.

The Tropical Cyclone tracks from the 06 and 18 UTC forecast cycles became operational with the Implementation of IFS Cycle 47r2.


  1. Hello,

    Can you confirm that these BUFRs at 06 and 18UTC are still under test and are not operational like 00 and 12UTC?

    Best regards

    1. Hello,

      Tropical Cyclone tracks at 6/18 UTC became operational with the Implementation of IFS Cycle 47r2.