Hello B Fraser,
I like the QNE = Nerdy for 29.92 on the subscale remark. Now I have a method of remembering it. Just to confirm, QFE = QNH when aerodrome is at sea level, right?
What about this reduction from aerodrome station pressure level to the guestimated "would be" station pressure level at sea level? Is this QFF? I can't remember. I remember though about reading using the average temperature for a given past number of hours? Problem is, all the books and online resources talk about the way to do it but don't give an exact numeric example showing how to do it. So if anyone wants to demonstrate their wits please feel very free to do so.