Getting back to the original questions as to why AWOS, METAR, ATIS, and tower winds are different, I hope that has been answered.
The question was never asked!
Actually, it was. The OP was asking why the winds from tower were different that ATIS and the changes while lining up.
I explained the different reporting standards, and why there are differences. Not only different between mag/true, but simply the differences and changes in the winds.
The difference between true and mag needs to be understood. Different Systems will add the magvar or not, so it is important to understand what to input and where.
As shown by many applications, the magvar for the aerodrome is a setting. The ac uses true when measuring the winds. Forecasts and enroute are in true.It must be understood when inputting winds to the ac, if the winds you are using include the magvar correction or not.
What needs to be understood is what the ANSP has decided to provide. That was the basis for my comment on crosswinds. IF it has been decided to include crosswinds in the broadcast, it is magvar, but this is not typical. When crosswinds are not provided, and up to the driver to compute, the winds are in true. From what I have experienced, most require the driver to calc the wind.
If Aus has decided that is too much, and has provided the crosswinds, that is all good, but it must be understood, when inputting the winds on the ac, if the FMS is going to correct the winds to the magvar in the database or not.
There is the worldwide standard for aviation, and I provided that as the standard, and required reporting back a few posts. Depending on conditions, there will be differences, due to the reporting frequency and averaging.
The provision if you read it it is true, if you hear it, it is mag, is what we use as a guide for the input to the FMS. When sharing wind data between aircraft, is is important to understand the format.
The AWOS winds are measured at the aerodrome in true, and at 10m, per the frequency, averaging and parameters stated in post 286. The AWOS system corrects the winds by magvar for the individual runways to report crosswinds.
The AUS AIP states for runway ops it is mag, and non-runways ops winds re true, it does not detail what runway ops means.