Rossby wave packets (RWPs), are atmospheric perturbations linked to the occurrence of extreme weather events such as heatwaves, extratropical cyclone development and other equally destructive phenomena. Under certain circumstances, these packets can last from several days to 2–3 weeks in the atmosphere. Therefore, forecast models should be able to correctly predict their formation and development to enhance extreme weather events prediction from 10 to 30 days in advance. In this study, we assess whether the NCEP and IAP-CAS sub-seasonal forecast models can predict the evolution of observed RWPs that last more than 8 days (long-lived RWPs or LLRWPs) during southern hemisphere summer. Results show that the NCEP (IAP-CAS) model forecasts LLRWPs that appear eastward (westward) from the observed LLRWPs. Both models forecasted LLRWPs that rapidly lose energy after the 6^th–7^th lead day of simulation, which could limit LLRWPs prediction to the synoptic time scale. Additionally, both models better forecast LLRWPs when the packets manifest in the eastern Pacific. Southern Annular mode (SAM) and El Niño Southern-Oscillation (ENSO) do not seem to exert a large influence in the representation of LLRWPs. Nevertheless, during the best LLRWPs forecasts, the observed circulation anomalies signal the manifestation of negative SAM events. In contrast, both forecast models struggle at forecasting LLRWPs when a blocking situation develops to the South of Australia. Lastly, an inactive Madden Julian Oscillation (MJO) seems to favor the development of accurate LLRWPs forecasts, whereas during phases 3, 5 in the NCEP model and 3, 8 for IAP-CAS, the models struggle at forecasting LLRWPs.

中文翻译：

---

预测模型在多大程度上代表了南半球夏季观测到的长寿命罗斯比波包？

罗斯贝波包 (RWP) 是与热浪、温带气旋发展和其他同样具有破坏性的现象等极端天气事件的发生有关的大气扰动。在某些情况下，这些包可以在大气中保存几天到 2-3 周。因此，预报模型应能够正确预测其形成和发展，提高极端天气事件提前10至30天的预测能力。在本研究中，我们评估 NCEP 和 IAP-CAS 次季节预报模型是否可以预测南半球夏季观测到的持续超过 8 天的 RWP（长寿命 RWP 或 LLRWP）的演变。结果表明，NCEP（IAP-CAS）模型预测的LLRWP出现在观测到的LLRWP的东（西）位置。^第– 7^个模拟的领先日，这可能会将 LLRWP 预测限制在天气时间尺度内。此外，当数据包出现在东太平洋时，这两个模型都能更好地预测 LLRWP。南方环形模态（SAM）和厄尔尼诺南方涛动（ENSO）似乎对 LLRWP 的表征没有产生很大的影响。然而，在最佳的 LLRWP 预报期间，观测到的环流异常表明了 SAM 负事件的表现。相比之下，当澳大利亚南部出现阻塞情况时，两种预测模型都难以预测 LLRWP。最后，不活跃的马登朱利安振荡 (MJO) 似乎有利于准确 LLRWP 预测的发展，而在 NCEP 模型的第 3、5 阶段和 IAP-CAS 的第 3、8 阶段，模型在预测 LLRWP 方面遇到困难。