Dear Sonia,
Once again, thank you for your valuable enquiry. I did investigate the station you mentioned, and indeed these wind observations are not included in the WDQMS statistics. I have actually included the text below in the WDQMS FAQ so that information is available in the WDQMS documentation.
Regards,
Cristina
WDQMS FAQs (https://confluence.ecmwf.int/display/WIGOSWT/FAQs)
How are “variable wind” measurements reported in SYNOP considered in WDQMS statistics?
In SYNOP reports, a variable wind (or light and variable conditions) is encoded with a wind direction of 99, indicating a valid observation rather than missing data. However, WDQMS statistics are based on the 10m zonal and meridional wind components from NWP DA systems. For 10m variable wind measurements, these components cannot be derived, so O–B departures cannot be calculated. As a result, such reports are excluded from WDQMS statistics. While meteorologically valid, variable 10m wind reports are not usable for DA‑based metrics in WDQMS. A high frequency of these reports can reduce effective data availability and may negatively affect the station availability scores for wind.