The monsoon has made a further advance today, with the rains reaching more parts of Tamil Nadu, most parts of Tripura, and remaining parts of Nagaland, Manipur and Mizoram. It has also checked into Assam and Arunachal Pradesh, the India Met Department (IMD) said, though the Arabian Sea 'arm' remains briefly stalled on the West Coast, to the North of Karnataka.
ALIGNMENT UNCHANGED
So, on the West Coast, its alignment remains unchanged on Sunday along Shirali, Hassan, Mysuru, Salem and Karaikal, while to the East, it has touched Lumding and North Lakhimpur.
The IMD assessed conditions as favourble for its further advance to more parts of the South Peninsula, Assam, Arunachal Pradesh, remaining parts of Tripura and more parts of Meghalaya.
This is expected to happen over the next two to three days with the development of favourable circulatory features and strengthening of cross-equatorial winds. Rainfall activity would increase over parts of Maharashtra and Goa from Wednesday (June 6), leading to the advance of the monsoon over these areas.
Wind profile maps this morning show a full and frontal monsoonal assault on the West Coast is being delayed only due to a brief distraction, yet again, over the Arabian Sea waters off Oman and Yemen.
'ROGUE CIRCULATION'
This is attributed to the sheer strength of the flows -- showing how the larger monsoon system has been keeping good health -- as they turn off the Somalia and Yemen coasts towards India.
A part of the flows has been appropriated by a circulation off Somalia and Yemen as they take a U-turn there, leaving only the rest to reach mainly the Kerala and adjoining Karnataka coasts for now.
The rogue circulation is expected to die out over the next three days (by June 6, Wednesday) when the flows would be let free to make a full-blooded run towards India's West Coast.
Meanwhile, it is becoming clear that the Bay and the Arabian Sea must thank the 'persuasive skills' of a tropical depression in the neighbouring South China Sea for the strengthening of flows.
The flows across the Arabian Sea and the Bay would strengthen in tandem with this depression as it moves from its current location off Hanoi, Vietnam, towards South-West China.
HELP FROM PACIFIC
It is on the trail of these flows that helpful circulations form to anchor them over these seas and direct the rain bands back to the mainland across the Central and Peninsular India.
This would make for a strong monsoon onset over Mumbai around the scheduled date of June 10 (there could be a surprise on the upside here) and plentiful rains over Central India during this period.
This phase would also see a low-pressure area or depression form in the 'head' Bay, to coincide with the growth of a follow-up circulation in the South China Sea into a typhoon (cyclone).
This is in line with the outlook of the European Centre for Medium-Range Weather Forecasts until June 10. The IMD points to a circulation off Mumbai during this phase, intensifying rains on the West Coast.
Meanwhile, heavy rains have been lashing parts of the Kerala coast since this morning. Thiruvananthapuram city saw overnight rains gaining urgency into the morning and later into noon.