North-east monsoon rains have ceased over Kerala & Mahe, south interior Karnataka, Tamil Nadu, Puducherry & Karaikal, Rayalaseema and adjoining areas of Coastal Andhra Pradesh & Yanam on Monday, exactly a month after the normal date.
The 2024 season may come to an end, but an easterly wave crossing southern parts of Bay of Bengal may trigger light to moderate rain at a few places over Tamil Nadu, Puducherry & Karaikal for three days from Thursday until Saturday (January 30 to February 1), an India Meteorological Department (IMD) update said on Monday.
Most rain in Rayalaseema
Heavy rain has been warned off at isolated places over Tamil Nadu, Puducherry & Karaikal these days and over Kerala & Mahe on Friday. The core October to December (2024) north-east monsoon season saw Rayalaseema post the rainfall with an excess of 46 per cent. South interior Karnataka ran up a close second with 43 per cent, as per IMD records.
Coastal Karnataka stood third with 34 per cent; Tamil Nadu, Puducherry & Karaikal, 33 per cent; followed at a distance by north interior Karnataka (4 per cent). Kerala & Mahe (-1 per cent; Lakshadweep (-3 per cent), and Coastal Andhra Pradesh & Yanam (-13 per cent) fell in the normal rain category, while Telangana is the lone meteorological subdivision to witness a deficit (-34 per cent).
More easterly waves?
Global model forecasts indicate the possibility of more easterly waves, which travel straight towards Sri Lanka and southern parts of Tamil Nadu. These waves may be active during the first three to four days of February, as projected by negative outgoing long-wave radiation values (indicating cloud presence over Sri Lanka and southern India).
The cessation of north-east monsoon shifts focus to the southern hemisphere where Australia is eagerly waiting for its own rain season. With a helpful MJO wave predicted to enter the Maritime Continent, the northern coast of Australia is favoured to be the most active region for tropical cyclone activity and likely onset of the monsoon, much delayed beyond the normal date.
Australian monsoon
The average monsoon onset date here over Australia is in the last week of December; it has been delayed by close to a month now. Earlier last week, the Australian Bureau of Meteorology said monsoon-like conditions and tropical activity had evolved over a region extending from near Darwin to parts of the coastline of northern Western Australia.
But classical onset of monsoon at Darwin had yet to occur. This requires technical wind criteria to be achieved. The wind criteria being not met in the last week, would make it the latest recognised monsoon onset at Darwin on record. But arrival of a crucial and helpful Madden-Julian Oscillation (MJO) during this and next week wave increases chances of monsoon development.
MJO wave is on way
An MJO wave is forecast to enter Maritime Continent (northwest of Australia) during January 29-February 11. This may make northern coast of Australia most active region for cyclone activity. Both European Centre for Medium-range Weather Forecasts and Global Ensemble Forecast System indicate highest probability of cyclone genesis to north-west of Australia. As the MJO continues to move eastward, enhanced probabilities of cyclone genesis will spread to the northeast coast.