Some conjecture... El Nino, though it is a huge deal on tropospheric temperatures on the year it has happened, does not spread its influence over the whole globe at once. This has got to do with the simultaneous mess it works on the Pacific equatorial currents, that does influence the whole cycle of oceanic gyres on earth that are north of Antarctic Circumpolar Current. The tropospheric heat punch El Nino delivers should indeed take a while to get noticed on other tropical basins. The huge amounts of rain (where it rains) would be ever so slightly warmer than normal during the year El Nino has happened. These then flow back out to sea in a year or so, so the year after every coastal current and oceanic gyre (partly via air) would have had time to catch the El Nino influence. As the currents of the world return to their normal ways after El Nino the influence could be noticed all over the world. Too bad (for the guy trying to catch these) they are not uniform so in some areas these are very hard to catch. Oceanic gyres aren't too quick to respond to this so I'd throw in a number of 18 months, as the limit of the influence of a single El Nino episode. Thus it could (and I mean it!) be 2017 is the year for Arctic to notice the El Nino we're witnessing, at least by then the Kuroshio current should be back up in strength (has it waned during this nino?), throwing its heat towards north, and the Atlantic has received the warmer rains produced by Nino.
But but, 'won't the clouds from el nino spewed moisture reach higher and thus rain cooler?', I hear some denier asking, and my answer would be, yes, eventually, but they are out of their normal habitat so initially they rain just where the normal clouds rain. not a good answer I admit but the only one I can come up with this early (6 AM here).
MMh, that sound like El Nino is a big and a huge deal, almost like there's nothing else to follow, well, it is a big deal, but the reason (to me) why it's so hot this time around is AGW, so there (huh, saved the scientificallic point, at the last moment).