Thre are two parts to using the NAO for winter forecasting.
First you have to forecast the seasonal NAO(DJF).This usually will be a sign and anomaly figure.METO do make this forecast for each winter but I have yet to see any stats on accuracy of this forecast.It may be that just getting the sign right is enough to count as a correct forecast.
Secondly even if the forecast sign and value are OK then you have to look at how NAO values relate to the very important winter temperature value.
I've just looked at the NAO for the winters 1873/74 to 2012/13.In these 140 years the NAO signs + or - and the expected CET temperature anomalies ie warm or cold were correct in 72.5% of years (NAO + years 70% correct,NAO - years 75% corrrect.
Looking at values as well as sign METO are on record as saying that the correlation beween actual NAO values and accomanying CET is 0.60 ie the NAO values account for c 40% of the CET variation.As forecast NAO values are never going to be 100% so correaltions between firecast NAO and actual CET are likely be below 0.60.
Doies anyone have a link to buy/download the paper?
Thanks
Originally Posted by: roger63