Hi Dan,
Yes, Tristars were occasionally delayed, but the past year has been totally unlike previously. I have been up and down the UK-FI route in the region of 100 times over the past 30 years. Prior to this year, I can remember maybe five or six times that I had weather related delays. During 2015 I had three consecutive flights with more than 24 hours delay due to airfield closures. Something has definitely changed.
Maybe the way the Met Office processes information has changed. I do not recall when they started using the 5///// turbulence group in the TAFs - my impression is that it is only in the last couple of years. Out of interest, do any of you with wider international experience recall seeing this group being used anywhere other than the Falklands?