Root-mean square errors in forecasts of normalized eddy kinetic energy (EKE) (200-hPa) are used to evaluate potential predictability. The results show that errors in initial conditions in the tropics grow appreciably faster than in the extratropics. Potential predictability extends out to about 4 days in the tropics (18-20N) and 9 days in the extratropics. Forecast errors in the tropics also quickly propagate to the extratropics, as demonstrated by experiments in which initial conditions are only perturbed in the tropics. Forecast errors in NEKE (200-hPa) on scales directly related to the MJO grow slower than in non-MJO variability. For this particular case study, potential predictability of precipitation extends to about 1-5 days over most of the CONUS but to longer leads (7-12 days) over regions with orographic precipitation in California. The results also show that errors in initial conditions on small scales relative to the large-scale characteristics of the MJO can quickly grow, propagate to the extratropics and degrade forecast skill of precipitation over the CONUS.
This presentation will also show results for other MJO events using global forecasts from the Subseasonal-to-Seasonal Prediction (S2S) Program. The main goal of the Subseasonal-to-Seasonal Prediction (S2S) research program is to explore sources of potential predictability on lead times beyond two weeks. The presentation will discuss how forecast errors in EKE vary across multi-scales during different phases of the MJO life cycle.