The advent of the NEM is getting delayed this year.
Vagaries predicts its advance around the 24th. taking into considerations the withdrawal of the SWM. The SWM lingers on, and even today, on the 17th, is still prevailing over parts of Karnataka and T.N.
The overall delayed actions, beyond forecast estimates, is mainly attributed to the stubborn SWM, and to some extent the weak MJO not "supporting" the fast formation of NEM currents in the Bay. Cooler SSTs are long overdue west of Java and Sumatra.
But, the upper winds are showing signs of "resigning" and changing. The Mascrene highs have lost their grip, and are seasonal and weaker, and the Tibetan/Siberian High is taking shape ,though late.