I wanted to look at what type of blocking followed December +3.5 or greater daily AO readings like we just experienced. I counted 9 Decembers when the AO rose this high and included the dates on which it occurred. ftp://ftp.cpc.ncep.n...1.current.ascii 12/25/51......+3.5 Blocking developed during February and March of that season. 12/20/71....+3.8 JAN-FEB east based 12/21/75....+3.5 1/15-1/30 76 12/2/79 was the strongest December daily +AO reading that I could find coming in at a +5.0.