The current status of statistical and dynamical MJO prediction in an operational forecast context

The MJO has numerous global impacts affecting weather and climate, both in the Tropics and Extratropics. It has been shown that the MJO can affect monsoon systems, modulate tropical cyclone activity and influence the timing and intensity of the El Nino-Southern Oscillation. The impacts of the MJO are not confined to the Tropics alone and the variation in atmospheric heating and upper-level divergence associated with the MJO often modulates the mid-latitude circulation. For these reasons, NOAA's Climate Prediction Center (CPC) monitors and predicts the MJO operationally to aid both U.S. domestic and global interests.

This paper reviews the current status of MJO prediction operationally at CPC (from both internal and external forecast tool sources) and will include evaluation of a few statistical approaches, in varying forms, as well as from operational dynamical model forecasts. The latter will primarily focus on realtime MJO forecasts of the Wheeler and Hendon (2004, hereafter WH04) MJO index as a function of season, phase and other factors. It will be shown that the forecast skill from some dynamical forecast systems has increased markedly in recent years and has surpassed many available realtime statistical based techniques. In fact, WH04 MJO index forecasts from the European Centre for Medium Range Forecasts (ECMWF) and National Centers for Environmental Prediction (NCEP) Climate Forecast System Version 2 (CFSv2) on average indicate forecast skill beyond three weeks under certain circumstances.

The paper also hopes to highlight gaps and remaining challenges from an operational forecast perspective and environment with respect to our understanding of the MJO, in addition to provide a current assessment of our predictive capability. Some discussion of the MJO activity observed during the Dynamics of the MJO (DYNAMO) field campaign will also be included. The evolution of MJO events observed during the field campaign further bring to light additional MJO prediction issues to be targeted in the future to improve operational MJO prediction and lead time on potential impacts in both the U.S. and globally.