In a few words what is the general model to explain it?

Is it because the atmosphere becomes a better heat sink so it can store more energy? And then consequently release more of it?

I am no expert, but I think the general intuition is that more energy means more violent fluctuations due to dynamical nature of weather. Just like water that is being more heated has stronger turbulences in it.

More specifically, extreme events in the moderate latitudes are explained by slowdown and amplification of Rosby waves: https://en.wikipedia.org/wiki/Rossby_wave