Southwest Monsoon Arrives over Southern Parts of Kerala and Tamil Nadu: IMD
By TWC India Edit Team
The southwest monsoon season has officially made its onset over the southern parts of Kerala, the India Meteorological Department (IMD) confirmed on Thursday afternoon.
The official statement released by the IMD reads: "Southwest Monsoon has advanced into some parts of south Arabian Sea, Lakshadweep area, south Kerala, south Tamil Nadu, remaining parts of Comorin-Maldives area and some more parts of southwest Bay of Bengal today, the 3rd June 2021."
As per the IMD, the following criteria were fulfilled to declare the onset over Kerala:
- More than 60% of the 14 rainfall monitoring stations reported rainfall 2.5 mm or more in the past two days consecutively. Also, the spatial distribution of rainfall over Kerala remained fairly widespread during the past two days.
- Westerly winds have strengthened in the lower levels (wind speed up to 20 knots) and satellite-derived winds suggest that 15-20 knots westerly winds prevail up to 600 hPa as of today.
- There is persistent convection (cloudiness indicated by Outgoing Longwave Radiation values
This onset on June 3 marks a 2-day delay in the arrival of monsoon rains over God's Own Country, as they typically begin in Kerala on June 1.
Earlier, the IMD had predicted that the monsoon season will commence in Kerala a day earlier than normal, on May 31. This date was later revised to June 3, with the weakening of lower-level southwesterly winds due to the eastward progression of the Madden-Julian oscillation (MJO) believed to be the likely cause for the delayed onset.
Now that the monsoon showers have begun over Kerala, the season's commencement over the rest of the Indian states is expected to get slightly delayed as well.
The IMD's latest update has indicated that the monsoon will advance into the remaining parts of south Arabian Sea, Kerala and Lakshadweep, and some parts of central Arabian Sea, Tamil Nadu & Puducherry, Coastal & South Interior Karnataka, Rayalaseema, and south and central Bay of Bengal during the next two days.
However, the progress of the western end of the monsoon trough is expected to remain slow in the first two weeks of June, as the next favourable phase of MJO over the Indian Ocean is expected in the third week in June. Due to this, rainfall could also remain subdued across the west coast of India till MJO kicks off more convection in the second half of June.
Overall, the IMD has forecast a slightly wetter monsoon season across India this year, with the precipitation between June-September 2021 expected to be 101% of the Long-Period Average (the average monsoon rainfall from 1961-2010, which stands at 88 cm). Back in April, IBM’s The Weather Company (TWC) had also predicted a marginally wetter-than-normal season this year, expecting rainfall worth 101% of the seasonal norm.