Gotcha.
This is precisely why timing is just as, if not, more important when dealing with the "sensible" weather and when it comes to the states of PNA, EPO, NAO, AO, etc. its their trend over a 5-7D period which is more important than just want the index looks to become or average out to.
I wish there was an easy way to do this and apply to historical events and for research purposes. I still would one love love to be able to take the daily index levels of the various indices and compute a weekly/bi-weekly rolling average. But I think this is extremely complex. I don't think its as simple as just taking the daily values and simply dividing by 7 or 14. A program could do this extremely easily, just have to come up with the proper equation.