The present report is a collection of research results presented, by IITM scientists and other experts at the IITM Monsoon Discussion Forums (IMDF) during conspicuous boreal summer of 2015. The evolution of the consecutive deficit Indian summer monsoon, with developing El Niño phenomenon over the Pacific, turned out to be the fourth intriguing episode of last century. This report highlights the challenging regional and global research as well as prediction aspects of the complex atmosphere-ocean-coupled Asian monsoon system, which was dominated by faster mode of rainfall variability. The prominent elements of this system are evolution of the canonical El Niño, ENSO induced anomalous Walker circulation, weakening of Southwest monsoon flow, recurvature of west-Pacific tropical cyclones, isolated extreme rainfall events and recurrent dry spells over South-Asia during 2015.