15th April:

Vagaries' Views: Our views are given taking into consideration the efforts put in by the scientists of various agencies and the IMD. With due respect to their probabilities, we consider that , as the agencies have termed it'" estimation"  of Monsoon.

Is it possible ever to make a genuine weather forecast 6 months ahead?
Obviously not, never accurately, but just a guessed estimate.
The South West Monsoon also cannot be quantum forecasted in April, for " actual performance " in August or September.

As mentioned in MW - 1, the April parameters occurring in April form and contribute towards the estimated performance of the Monsoon rains... For next 2/3 months.
How is it possible to forecast an event based on certain  parameters when the same parameters have not yet happened  ? Forecast can be made after studying and evaluation of the parameters. And that's possible only after the SST/Temperature/pressure/gradient/ Core Low Pressure build up/Upper Air Streams and other parameters actually happens.
Vagaries has mentioned this before, thus is unable ( impossible) to give the actual SWM strength or performance, specially regionwise.
Arrival dates can be and will be announced soon.. (  Seems early for Kerala).