Wind Direction offset?

Simple question… I think.

If I select +20 degrees for wind direction offset… am I saying that North is 20 degrees to the left of the Tempest device North or 20 degrees to the right?

Or another way to ask is… does it add 20 degrees to the azmidth? i.e. if tempest says wind is from 040 does the offset of 20 degrees now register as 060 or 020?

Just want to make sure.

Mine is GUI and does exactly what it shows, i.e. real wind 0 deg, Tempest shows 45 deg so if I select -45 it will report 0 deg.

The real concern here is if your blue mark is without a doubt facing true north and you’re seeing a discrepancy then something is amiss with the sensor. Or it is mounted too low or near an obstruction like a fence, etc.