Found this tutorial video in which a real-world pilot is using the PMDG NGX to explain a bit about winter operations. Very revealing..
To be quite honest, this was a bit of an eye opener for me. Never really took the time to read the Supplementary Procedures about this, but it's all there (SP 16.1, see the PMDG documentation)
funny enough...somehow the word Ray-Ban is not to be found in the Boeing documents...while hugely important I think, to not being blinded by the bright white snow and low hanging sun in the winter...