Yeah Redroach just like the pressure was 992mb in summer too.
We know the temp was not 15 but have a look through the records and see if you think 992 is a good fit for the battle.
They either need to publish what the atmosphere is actually doing so proper conversions can take place or create a "test map" that has ISA conditions. So verification and "informed" discussion can take place. You would think they would've created such a map when they were beta testing. Oh that's right we are playing the Alpha.