G. Di Capua, M. Kretschmer, J Runge, A. Alessandri, R. Donner, B. van den Hurk, R. Vellore, R. Krishnan, and D. Coumou, 2018: Long-lead empirical forecasts of the Indian Summer Monsoon Rainfall based on causal precursors. Accepted in Weather and Forecasting. https://doi.org/10.1175/WAF-D-19-0002.1