The US forecasts indicate enhanced rainfall activity topped up by likely storms in both Arabian Sea and Bay of Bengal during two weeks ending November 6.
Arabian Sea has already seen a tropical cyclone named Murjan, which originated in the southeast basin and moved away to hit Somali coast in Africa.
Another likely cyclone is forecast to take shape in the same basin, which might travel north (unlike west as Murjan did) from central Arabian Sea.
This is expected to cause rain all along the west coast, with some heavy rain bands likely to reach north Gujarat, according to initial forecasts.
The other weather system (likely not reaching cyclone strength) is forecast to hit Sri Lanka and southern tip of peninsular India (south Tamil Nadu and Kerala). The India Meteorological Department expects a preparatory low-pressure area to form over South Andaman Sea by Saturday.
MJO WAVE
This is expected to travel mostly west and head towards the Tamil Nadu coast. Enhanced weather activity across peninsular seas and larger Indian Ocean is being underwritten by a prevailing wet phase of a Madden-Julian Oscillation (MJO) wave.
The Climate Prediction Centre of the US National Weather Services had indicated this movement more than a week ago.
Meanwhile, a trough (elongated area of lower pressure and conducive for weather activity) is lying in readiness along the west coast from Comorin to Maharashtra.