Good point, Victor! That event was an unusual one, for sure. We don't include it as a three-year La Niña because (as you said) there are only two boreal winters that qualify. ENSO peaks in the winter, and global impacts are strongest in the winter. Looking closely at that 1954-56 stretch, though, I must say I'm glad I didn't have to make forecasts (or write blogs!) during that one. Negative anomalies lingered through the winter of 56-57, but they weren't strong enough to qualify as La Niña and the tropical Pacific returned to neutral conditions. This is the second most likely scenario for winter 22-23, as illustrated by the bar chart above.