Some people wonder when El Niño will show up in the lower troposphere. It takes some months before the temperature of the lower troposphere peaks - up to three months later than the peak in surface temperatures. That means that it will still be a couple of months before the El Niño shows up strongly in lower troposphere temperatures.
Which I found surprising:
I find that surprising. The atmosphere has precious little heat capacity. Why would the lag be so large? What's you source?