Brad Ballish at NCEP noticed a large number of zero VAD winds from different stations getting into the global model and after some further review by NCEP and us, the VAD winds were turned off temporarily from all NCEP models today, the RUC as of 1900 UTC. These bad winds often had the highest VAD quality control flag. The RUC was flagging many but all of them with its buddy check QC. When data sources like VADs start to have systematic problems, it can be a real problem even with the buddy check, since bad obs can corroborate other bad obs. We'll try to get to the bottom of this next week.

If you have any knowledge about these zero winds or other flaky VAD winds, please post something.