Following Becker et al. 2014 approach ( 10.1175/JCLI-D-13-00597.1 ) 1-4 lead seasonal forecast correlation. 

The correlation is 100m OHC between EN4 4.2.1 analysis and ensemble mean of simulation members.
season Lead Season = 1 Lead Season = 2 Lead Season = 3 Lead Season = 4
Jan prediction
Apr prediction
Jul prediction
Oct prediction