There has been significant progress in understanding and predicting the global earth system to extended ranges beyond synoptic scales. We understand the need to replicate physical phenomena related to tropical convection, MJO, monsoons, and their teleconnections with midlatitude weather and climate in the global earth system models. However, despite progress there is still a pressing need to further improve subseasonal-to-seasonal (S2S) predictions, and to better understand the underlying predictability and its temporal modulation. .
This second session in a three part S2S-focused series invites presentations addressing both previous and ongoing research investigating the sources of predictability, and propagation of forecast errors and systematic earth system model biases that appear early in the forecasts, with the goal of tracing these errors both to their impacts on prediction, and backward to their causes, to support implementing S2S prediction improvements with temporal ranges between 2 weeks to 2 years. Particular applications include but are not limited to S2S prediction of precipitation, extreme temperatures, severe weather outlooks, drought, atmospheric rivers and the conditions that are thought to drive these phenomena. While this session focuses on predictions and predictability, Parts 1 and 3 of this 3-part S2S-focused series highlight stakeholder needs and S2S model development, respectively.


