Analysis: summer season predictions v observations

2020-2021 Summer season saw the La Niña signal convert to good rainfall and cooler temps in NSW, but the decile 1-2 rain in SE Qld was less telegraphed and completely missed by the majority of models. A prudent reminder that expert commentary on analogue or “like” years should remain a key part of due diligence and risk management, despite statistical methods falling out of favour among some scientists.

Reflection and key learnings: The 2020 La Niña was slow to arrive and patchy when it did. All but one GCM (US IRI) model got completely sidetracked by the warm SSTs and traditional La Niña precipitation projections. In this 2020-21 event, the atmospheric conditions were slow to align with the warm SST signal, not occurring until around mid-December. International commentators Jason Nicholls (@jnmet) and Ben Noll (@BenNollWeather) predicted the rainfall and convection to be more in-line with 1988-89 with NSW the main beneficiary (mid-panel text). The cooler-than-normal southern Coral Sea, based on research may well have reduced available convection and moisture for rainfall events and this was picked up by the IRI (US) model. This region appears to be warming up now at a rapid rate, so hopefully, those farmers get their turn this Autumn.